A

absolute volume 1. Of a granular material, the total volume of the particles, including the permeable and impermeable voids, but excluding the spaces between the particles. 2. Of fluid, the volume which the fluid occupies. 3. The displacement volume of an ingredient of concrete or mortar.

absorbed moisture Moisture that has entered a solid material by absorption and has physical properties not substantially different from ordinary water at the same temperature and pressure. Also see absorption.

absorbency The property of a material that measures its capacity to soak up liquids.

absorbent A material which, owing to an affinity for certain substances, extracts one or more such substances from a liquid or gas with which it is in contact, and which changes physically or chemically, or both, during the process.

absorber 1. A device containing liquid for absorbing refrigerant vapor or other vapors. 2. In an absorption system, that part of the low-pressure side of the system which is used for absorbing refrigerant vapor. 3. That part of a solar collector whose primary function is to absorb radiant solar energy.

absorber plate Same as solar collector.

absorbing well, dry well, waste well A well used for draining off surface water and conducting it underground, where it is absorbed.

absorptance In illumination engineering, the ratio of the absorbed flux to the incident flux.

absorption 1. The process by which a liquid, or a mixture of gases and liquid, is drawn into and tends to fill permeable pores in a porous solid material; usually accompanied by a physical change, chemical change, or both, of the material. 2. The increase in weight of a porous solid body resulting from the penetration of liquid into its permeable pores. 3. The increase in weight of a brick or tile unit when immersed in either cold or boiling water for a stated length of time; expressed as a percentage of the weight of the dry unit. 4. The process by which radiant energy, which is incident on a surface, is converted to other forms of energy. 5. See sound absorption. 6. See light absorption.

absorption bed A pit of relatively large dimensions which is filled with coarse aggregate and contains a distribution pipe system; used to absorb the effluent of a septic tank.

absorption coefficient See sound absorption coefficient.

absorption field, disposal field A system of trenches containing coarse aggregate and distribution pipes through which septic-tank effluent may seep into the surrounding soil.

absorption rate, initial rate of absorption The weight of water absorbed when a brick is partially immersed for one minute; usually expressed in grams per minute or ounces per minute.

absorption system A refrigeration system in which the refrigerant gas evolved in the evaporator is taken up in an absorber and (upon the application of heat) released in a generator.

absorption trench A trench containing coarse aggregate and a distribution tile pipe through which septic-tank effluent may flow, covered with earth.

absorption-type liquid chiller Equipment utilizing a generator, condenser, absorber, evaporator, pumps, controls, and accessories to cool water, or other secondary liquid, using absorption techniques.

ABS plastic A plastic of acrylonitrile-butadiene-styrene; has good resistance to impact, heat, and chemicals; esp. used for piping.

abstract of title An outline history of the ownership of a parcel of land, from the original grant, with changes in title, and with a statement of all mortgages, liens, encumbrances, etc., affecting the property.

abut To adjoin at an end; to be contiguous.

abutment A masonry mass (or the like) which receives the thrust of an arch, vault, or strut.

abutment piece See solepiece.

abuttals Those boundaries of one piece of land that abut on adjacent pieces.

abutting joint A joint between two pieces of wood, in which the direction of the grain in one piece is at an angle (usually 90°) to the grain in the other.

abutting tenon One of two tenons which are inserted in a common mortise from opposite sides, so as to touch each other.

ac, a-c, a.c. Abbr. for “alternating current.”

AC 1. On drawings, abbr. for “alternating current.” 2. On drawings, abbr. for armored cable. 3. Abbr. for air conditioning. 4. Abbr. for “asbestos cement.”

acacia Same as gum arabic.

Acadian cottage Same as Cajun cottage.

acanthus A common plant of the Mediterranean, whose leaves, stylized, form the characteristic decoration of capitals of Corinthian and Composite orders. In scroll form it appears on friezes, panels, etc.

ACB 1. Abbr. for asbestos-cement board. 2. Abbr. for “air circuit breaker.”

accelerated aging The speeding-up of the aging process in a material; obtaining, in a short time, the results that would occur in aging under normal conditions. The most common factors that increase aging include exposure of the material to water, ozone, oxygen, or sunlight.

accelerated life test A test in which one or more parameters (e.g., temperature) is increased or decreased beyond its normal or rated value to determine the resulting deterioration within a reasonable time period.

accelerated weathering A laboratory testing technique to determine, in a relatively short time, the weather resistance of a paint film or other exposed surface.

accelerating admixture An admixture that speeds the setting and/or the early strength development of hydraulic concrete.

acceleration 1. The rate of change of the velocity of a moving body. 2. The rate of change, esp. the quickening of the natural progress of a process, such as hardening, setting, or strength development of concrete.

acceleration of gravity (g) The acceleration produced by the force of gravity at the surface of the earth. (By international agreement the value of g is 386.089 inches per second square = 32.1740 feet per second square = 9.80665 meters per second square.)

acceleration stress In a wire rope (or the like), the additional stress imposed as a result of the acceleration of the load.

accelerator 1. A substance which, when added to concrete, mortar, or grout, increases the rate of hydration of a hydraulic cement, shortens the time of set, or increases the rate of hardening or strength development. 2. A substance, added with a curing agent, to speed a vulcanization process and enhance the physical properties of a vulcanized material. 3. Same as accelerating admixture.

accent lighting Any directional lighting which emphasizes a particular object or draws attention to a particular area.

acceptable air quality Inside a building, air that is free of harmful concentrations of contaminants and that is judged acceptable to at least 80% of the building’s occupants.

acceptable water pressure See maximum acceptable pressure and minimum acceptable pressure.

acceptance See final acceptance.

acceptance test A test conducted by a purchaser (or an agent thereof) (a) to determine if the material, devices, or equipment delivered conforms to the purchase contract specifications and/or (b) to determine the degree of uniformity of the product supplied by the vendor.

access A means of approach, e.g., a road, street, or walk.

access door A door, usually small, which is provided through a finished construction, as into a duct, through a ceiling, behind a wall, in a large piece of mechanical equipment, etc.; used to provide a means of inspection of equipment or services housed within.

access eye See cleanout, 1.

access floor Same as raised floor.

access flooring system See raised flooring system.

accessibility standards See Americans with Disabilities Act and Uniform Federal Accessibility Standards.

accessible 1. Allowing physical contact, as by means of an easily removable cover or door or a part of the building structure or finish materials. 2. Providing access to a fixture, appliance, or piece of equipment; removal of a cover, panel, plate, or similar obstruction may be required. 3. Said of a building, facility, or site that can be approached, entered, and used by a physically disabled person. 4. According to the Americans with Disabilities Act (ADA), a term used for a space that complies with the standards of the Act for those having disabilities or impairments (including visual, hearing, mental, or mobility), and does not require the assistance of others to enter the space.

accessible means of egress A path of travel, usable by a mobility-impaired person, that leads to a public way.

accessible route According to the ADA, a continuous, unobstructed path between all accessible elements and areas of a building, including corridors, ramps, and elevators; the route must provide adequate clearance around desks, furniture, and the like.

accessible space A space that complies with all provisions of the Americans with Disabilities Act.

accessory building A secondary building, whose use is incidental to that of the main building located on the same plot.

accessory use The use or occupancy incidental to the principal use or occupancy of a building.

access panel A removable panel (usually secured with screws) in a frame which is usually mounted in a ceiling or wall; provides access to a concealed item that does not require frequent attention.

access plate A removable plate (usually bolted in place) that provides access to an area that seldom requires attention; permits inspection of an otherwise inaccessible area.

access platform Same as cherry picker.

access stair A stair, from one floor level to another, which does not serve as a required exit stair. Also see exterior stair.

access street A low-traffic-volume street, usually comprised of individual dwelling units, which conveys vehicular traffic to or from a street carrying heavier traffic.

access way A roadway, usually paved, intended to provide ingress and egress of vehicular traffic from a public right-of-way to an off-street parking area.

accident A sudden, unexpected event identifiable as to time and place. Also see occurrence.

accidental air See entrapped air.

acclivity The upward slope of a hillside.

accolade An ornamental treatment, used over an arch, a door, or a window, composed of two ogee curves meeting in the middle; often a richly decorated molding.

accompaniment A decoration added to a building with the intention of enhancing its appearance.

accordion door 1. Any fabric-faced door which is hung from an overhead track and folds back like the bellows of an accordion. 2. A hinged door consisting of a system of panels which are hung from an overhead track. When the door is open, the faces of the panels close flat against each other; when the door is closed, the edges of adjacent panels butt against (or interlock with) each other to form a solid barrier.

accordion partition A fabric-faced partition which is hung from an overhead track and folds back like the bellows of an accordion.

accouplement The placement of columns or pilasters close together, in pairs.

accrued depreciation 1. The reduction in actual value of property over a period of time, as a result of wear and tear, obsolescence, etc. 2. The accumulated reductions in the stated value of property over a period of time, entered on balance sheets for accounting or tax purposes.

accumulator 1. In a refrigeration system, a storage chamber for low-side liquid refrigerant; also called a surge drum or surge header. 2. In a refrigerant circuit, a vessel whose volume is used to reduce pulsation.

ACD Abbr. for automatic closing device.

ACE Abbr. for “Architects Council of Europe.”

acetone A highly flammable solvent which evaporates rapidly; used in lacquers, paint removers, thinners, etc.

acetylene A colorless gas, when mixed with oxygen, burns at a temperature of about 3500°C; used in welding.

acetylene torch A torch, used in welding and in metal cutting, which is operated by compressed acetylene gas and oxygen.

AC generator A generator which produces alternating current when driven by a prime mover.

Achaemenid architecture An architecture developed under the Achaemenid rulers of Persia (6th to 4th cent. B.C.) by a synthesis and eclectic adaptation of architectural elements which included those of surrounding countries. In the hypostyle hall it achieved a highly original new building type.

achromatic Said of architecture that is without color, for example, the white buildings of Greek Revival.

achromatic color White light; a color that does not elicit hue.

ACI Abbr. for “American Concrete Institute.”

acid-etched Said of a metallic surface (e.g., a nail) that has been treated in an acid bath to provide a rough surface.

acidic Said of igneous rocks containing more than 65% silica.

aciding The light etching of a cast-stone surface.

acid lead Fully refined lead to which a small amount of copper has been added; 99.9% pure.

acid neutralizer A device installed in a drainage system into which the discharge of acid is probable; neutralizes the discharge sufficiently to permit it to enter the drainage system safely.

acid polishing The polishing of a glass surface by acid treatment.

acid resistance The degree to which a surface, such as porcelain enamel, will resist attack by acids.

acid-resistant brick Brick suitable for use in contact with chemicals; usually laid with acid-resistant mortars.

acid-resistant cast-iron pipe A cast-iron pipe containing between 14.25 and 15% silicon and small amounts of manganese, sulfur, and carbon; manufactured in the same dimensions as cast-iron pipe.

acid soil Soil having an acid reaction; usually a soil having a pH value of less than 6.6.

acisculis A mason’s small pick, with a flat face and pointed peen.

acorn A small ornament in the shape of a nut of the oak tree; sometimes used as a finial, pendant, or decorative element within a broken pediment, or as a decoration on a carved panel.

acous 1. Abbr. for acoustical. 2. Abbr. for acoustics.

acoustic, acoustical The qualifying adjectives acoustic and acoustical have the following meanings: arising from, actuated by, containing, producing, or related to sound. In general, acoustic is used when the term being qualified designates something that has the properties, dimensions, or physical characteristics associated with sound waves; acoustical is used when the term being qualified does not explicitly designate something that has the properties, dimensions, or physical characteristics of sound (e.g., acoustical engineering). However, sometimes these two terms are used interchangeably.

acoustical barrier See sound barrier.

acoustical board See acoustical ceiling board.

acoustical ceiling A ceiling covered by, or formed of, an acoustical material.

acoustical ceiling board An acoustical material in board form, designed primarily for suspended ceiling application.

acoustical ceiling system A structural system for supporting an acoustical ceiling; may incorporate lighting fixtures and air diffusers.

acoustical door A solid, heavy door which is gasketed along the top and sides; usually has an automatic door bottom; especially constructed to reduce noise transmission through it; usually carries a sound transmission class (STC) rating, which is a measure of its sound insulation value.

acoustical duct lining See duct lining.

acoustical insulation board A porous material in board form, designed or used as an acoustical material or as an element in a sound-insulation construction.

acoustical lay-in panel An acoustical ceiling board designed to be laid into an exposed grid suspension system.

acoustical material Any material especially designed to absorb sound.

acoustical model A model of an auditorium or room used to study certain acoustical properties of the full-sized enclosure, such as the distribution of sound pressure, the paths of sound rays, and focusing effects.

acoustical panel Same as acoustical lay-in panel.

acoustical plaster A special low-density sound-absorptive plaster, applied in the form of a finish-coat, to provide a continuous finished surface.

acoustical power See sound power.

acoustical sprayed-on material An acoustical material applied by a spray process to form a continuous finished surface.

acoustical tile An acoustical material in board form, often having unit dimensions of 24 in. by 24 in. (approx. 61 cm by 61 cm) or less. Usually used on ceilings but also may be applied to side-walls.

acoustics 1. The science of sound, including the generation, transmission, and effects of sound waves. 2. The totality of those physical characteristics of an auditorium or room (such as the size and shape of elements on the walls or ceiling which scatter sound, the amount of sound absorption, and noise level within the room) which affect an individual’s perception, and judgment, of the quality of speech and music produced in the room.

acph Abbr. for “air changes per hour.”

acquiescence 1. An act of concurrence by adjoining property owners which resolves a boundary dispute or establishes a common boundary, where the definite or more accurate position of same has not or cannot be defined by survey. 2. The tacit consent of one owner, by not interposing a formal objection, to what might be an encroachment by an adjoining property owner over a questionable boundary.

acre A unit of land measurement equal to 43,560 sq ft or 4046.85 sq m; 1 sq mile (2.59 sq km) equals 640 acres.

acre-foot The amount of water required to cover an area of 1 acre to a depth of 1 foot; equivalent to 43,560 cubic feet (4046.9 m³); sometimes used as a measure of materials in place (e.g., gravel).

acrolith A statue or sculptured figure in which only the head, hands, and feet are of stone, the rest being usually of wood.

acropodium 1. An elevated pedestal bearing a statue, particularly if raised from the substructure on supports. 2. The plinth of a statue if resting on supports.

acropolis 1. The elevated stronghold of a Greek city, usually with the temple of the patron divinity. 2. (cap.) The Acropolis of Athens. 3. Any elevated group of buildings serving as a civic symbol.

acroterion, acroter, acroterium 1. Strictly, a pedestal at the corners or peak of a roof to support an ornament. 2. More usually, the ornament itself.

acrylic carpet A carpet having a combination of acrylic and modacrylic fibers; known for its stain-resistant qualities, high durability, and wool-like appearance.

acrylic fiber A synthetic fiber manufactured by polymerizing acrylonitrile.

acrylic paint A type of latex paint made from acrylic resins; also called acrylic latex paint.

acrylic resin, acrylate resin One of a group of thermoplastic resins made from esters of acrylic acid; exceptionally tough, stable, resistant to chemicals, and transparent; used as a binder, in sheet form, as an air-curing adhesive, and as the main ingredient in some caulks and sealants.

acrylonitrile-butadiene-styrene (ABS) A plastic used for piping in drainage systems, storm sewers, and underground electrical conduit.

ACS Abbr. for “American Ceramic Society.”

ACT. On drawings, abbreviation for “actual.”

act curtain, act drop, front curtain, house curtain A curtain, behind the asbestos curtain in a theater, which closes the proscenium and serves as an indication of the beginning or end of an act or scene.

act drop See act curtain.

acting area That part of a theater stage floor on which the actors perform.

acting area light A spotlight used to illuminate a selected acting area.

acting level A platform above the theater stage floor which is used for acting.

actinic glass A glass having a yellow tint which reduces the transmission of infrared and ultraviolet rays; sometimes used in factory windows or skylights.

action hinge Same as double-acting hinge.

activated alumina A form of aluminum oxide which adsorbs moisture readily and is used as a drying agent.

activated carbon See activated charcoal.

activated charcoal, activated carbon Charcoal obtained by carbonizing organic material, usually in the absence of air; usually in granular or powdered form; highly effective in adsorbing odors in air or in removing colors in solution.

activated rosin flux A flux having a resin or rosin base and containing an additive to increase wetting by the solder.

activated sludge Sewage sediment that has been subjected to vigorous aeration and the action of microorganisms.

activator Same as catalyst.

active door In a pair of doors, the leaf, 1 that is the first to open and is the leaf to which a lock is applied.

active earth pressure The component of pressure in a horizontal direction which a mass of earth exerts on a wall.

active lateral pressure The horizontal soil pressure which is exerted by soil on a retaining structure.

active leaf, active door In a door having a pair of leaves, that leaf to which the latching or locking mechanism is attached; usually the leaf that is permitted to open first; sometimes both leaves are active.

active sludge A sludge, 3 which is rich in destructive bacteria; useful in breaking down fresh sewage.

active solar energy system A building subsystem in which solar energy is collected and is transferred predominantly by mechanical equipment (fans, pumps) powered by energy not derived from solar radiation. Compare with passive solar energy system.

active sound attenuator A special type of sound attenuator that incorporates a sound source which generates sound waves intended to cancel some of the noise generated by the fans in an HVAC system.

activity In CPM terminology, a task or item of work that must be performed in order to complete a project.

activity duration In CPM terminology, the amount of time estimated as required to accomplish an activity.

actual start of construction The first placement of permanent construction of a building on a site, such as pile driving, or the pouring of slabs or footings.

acuminated Finished in a point, as a lofty Gothic roof.

acute angle An angle of less than 90°.

acute arch, lancet arch A sharply pointed arch whose centers are farther apart than the width of the arch.

a.d. Abbr. for “air-dried.”

AD 1. Abbr. for “air-dried.” 2. Abbr. for access door. 3. Abbr. for area drain. 4. Abbr. for “as drawn.”

ADA Abbr. for Americans with Disabilities Act.

Adamesque style An inexact term implying a derivation from the Adam style, but having possible differences depending on the time and location of application.

Adam Revival See Colonial Revival.

Adam style An architectural style based on the work of Robert Adam (1728–1792) and his brothers, predominant in England in the late 18th century and strongly influential in the US, Russia, and elsewhere. It is characterized by clarity of form, use of color, subtle detailing, and unified schemes of interior design. Basically Neoclassical, it also adapted Neo-Gothic, Egyptian, and Etruscan motifs.

adapt To make suitable for a particular purpose or new requirements or conditions, by means of modifications or changes.

adaptability The capacity of building spaces and elements for being altered or being added to for specific needs, as, for example, to accommodate the needs of persons with and without disabilities.

adaptable According to the ADA, a restroom or bathroom to which grab bars can be added or which can be otherwise altered to accommodate the needs of individuals with disabilities.

adaptable dwelling unit One of a number of dwelling units that is on an accessible route and equipped so it may be converted to be used, with a minimum of structural change, by all categories of physically disabled persons.

adaptation The process by which the eye changes sensitivity and becomes accustomed to more or less light than it was exposed to during an immediately preceding period.

adapter 1. A device for matching and properly connecting items, tubing, or devices (especially electric) which are of different size, operating characteristics, or design. 2. A device that enables different sizes or types of plugs, pipes, etc., to be joined.

adaptive use, adaptive re-use The extensive alteration, restoration, and/or renovation of an existing building so that it will serve a new or modified purpose. Also see building rehabilitation.

ADC Abbr. for “Air Diffusion Council.”

ADD. 1. On drawings, abbr. for addendum. 2. On drawings, abbr. for addition.

added lean-to Same as integral lean-to.

addendum A written or graphic instrument issued prior to the execution of the contract which modifies or interprets the bidding documents, including drawings, and specifications, by additions, deletions, clarifications or corrections; becomes part of the contract documents when the construction contract is executed.

addition 1. A floor or floors, a room, wing, or other expansion to an existing building. 2. In building code usage: Any new construction which increases the height or floor area of an existing building or adds to it (as a porch or attached garage). 3. An amount added to the contract sum by a charge order; also see extra.

additional service authorization An AIA form that authorizes additional work, 1 to be performed, for an additional fee, for services not covered in the originally specified scope of the architect’s work.

additional services The professional services which may, upon the owner’s request or approval, be rendered by the architect in addition to the basic services or the designated services.

additive A material, used in very small quantity, to modify a specific property of another material or otherwise improve its characteristics; used in paints, plasters, mortars, etc.

additive alternate An alternate bid resulting in an addition to the same bidder’s base bid. Also see alternate bid.

additus maximus In an ancient Roman amphitheater, a main entrance.

addorsed, adorsed Said of animals or figures placed back to back in decorative sculpture.

addressable system A fire alarm system whose integrity can be monitored and which provides easy identification of the location of an alarm condition; also provides for remote testing and monitoring of the sensitivity of the detectors from a control panel.

ADF In the lumber industry, abbr. for “after deducting freight.”

ADH On drawings, abbr. for adhesive.

adherend A body which is held to another by an adhesive.

adhesion 1. The joining of two surfaces as pieces of wood, metal, plastic, or other construction materials, by means of a viscous, sticky composition such as cement or glue. 2. The sticking together of two surfaces by means of physical and chemical forces such as those which bind a paint film to a surface.

adhesion bond The adhesion of mortar or grout to masonry units.

adhesion-type ceramic veneer Thin sections of ceramic veneer held in place by the adhesion of mortar to unit and backing, requiring no metal anchors; not more than 1¼ in. (3.2 cm) in overall thickness. Also see anchored-type ceramic veneer.

adhesion-type filter A type of air filter in which dirt particles are removed from air by adhering to the filter as the air flows through it.

adhesive A substance capable of holding materials together by bonding the surfaces that are in contact.

adhesive failure The separation of two surfaces joined by an adhesive, either by a force less than that specified by the manufacturer or by service conditions.

adiabatic Occurring without the gain or loss of heat.

adiabatic curing The curing of concrete or mortar in which adiabatic conditions are maintained during the curing period.

Adirondack Rustic style See Rustic style.

adit An entrance or passage.

adjoining grade elevation The average elevation of the final grade adjoining all exterior walls of a building, calculated from grade elevations taken at intervals (usually 10 ft or 3 m) around the perimeter of the building.

adjustable base anchor A device used to hold a doorframe above the finished floor.

adjustable doorframe A doorframe which has an adjustable jamb so that it can be installed in walls of different thicknesses.

adjustable hanger A hanger having a provision for adjusting its length.

adjustable multiple-point suspension scaffold 1. See mason’s adjustable multiple-point suspension scaffold. 2. See stone-setter’s adjustable multiple-point suspension scaffold.

adjustable proscenium On a theater stage, an inner proscenium which is variable in height, width, or position; may be hung from rigging overhead or floor-mounted.

adjustable shelving Shelving supported by metal clips or other movable supports, making it possible to adjust the height of individual shelves.

adjustable shore, adjustable steel prop A vertical shore used to support reinforced concrete beams and slab forms; usually all metal or a combination of wood and metal; can be raised or lowered within certain limits.

adjustable-speed motor An electric motor in which the speed can be varied gradually over a considerable range, but which, once adjusted, remains virtually unaffected by the load, 3.

adjustable square, double square A try square the arm of which is at right angles to the handle; the position of the arm may be moved so as to form an L or a T.

adjustable wrench Any one of several types of wrenches having one jaw fixed and the other adjustable; set to the desired size by means of a knurled screw.

adjustable administration of the construction contract See construction phase—administration of the construction contract.

administrative authority The individual, official, board, department, or agency established and authorized by a city, county, state, or political subdivision created by law to administer and enforce the provisions of a code.

admixture A material other than water, aggregates, lime, or cement, used as an ingredient of concrete or mortar, and added to the batch immediately before or during its mixing; used as a water repellent, as a coloring agent, as a retarder or accelerator (to modify its setting rate), etc.

adobe A heavy soil, composed largely of clay and silt in sufficient quantities to form a matrix in which sand particles are firmly imbedded; water is added, and straw, manure, and fragments of tile are sometimes combined with this mixture to provide increased mechanical strength and cohesion when it dries. It can be used as a plaster or be formed into bricks, often shaped by hand in a wooden form, then sun-dried; widely used in Spanish Colonial architecture and its derivatives. Adobe brick walls are often lime-plastered to improve resistance to weather; a coating such as slaked lime acts as a stabilizing agent.

adobe blasting Same as mud-capping.

adobe brick Large, roughly molded, sundried clay brick, usually of varying sizes.

adobe quemado An adobe brick that has been kiln-dried at a temperature lower than that required to produce a hard-burnt brick; usually deep red in color, relatively soft, and rough in texture.

adobero A box for mixing adobe and shaping it into bricks.

adopted street In Britain, a dedicated street.

ADS Abbr. for “automatic door seal.”

adsorbed water 1. Water which is held on the surfaces of a material by electrochemical forces; its physical properties are substantially different from those of absorbed water or chemically combined water at the same temperature and pressure. 2. Water which is bound to soil particles as a result of the attraction between electrical charges on their surfaces and water molecules.

adsorbent A material (such as activated charcoal) which has the ability to extract certain substances from gases, liquids, or solids by causing the substances to adhere to its internal surface without changing the adsorbent physically or chemically.

adsorption The action of a material in extracting a substance from the atmosphere (or a mixture of gases and liquids) and gathering it on the surface in a condensed layer; the process is not accompanied by physical or chemical change.

adulterine In the Middle Ages in Britain, said of a castle that was crenelated without a license to erect battlements. Such licenses were granted by the reigning monarch in exchange for a cash payment from the castle’s owner.

advance slope grouting Grouting by a technique in which the front of the mass of grout is forced to move horizontally through preplaced aggregate.

advance slope method A method of concrete placement in which the face of the fresh concrete moves forward as the concrete is placed; the face of the fresh concrete is not vertical.

advanced nursery stock A deciduous tree, of specified size, which has been transplanted several times and has had its roots pruned in preparation for its final transplantation.

adverse possession Occupation of property by one not the true owner, openly, notoriously, and continuously. See statute of limitations; squatter’s right; proscription.

advertisement curtain On the stage of a theater, a curtain which bears advertisements; usually behind the asbestos curtain, but sometimes (rarely) the asbestos itself.

advertisement for bids The published public notice soliciting bids for a construction project. Most frequently used to conform to legal requirements pertaining to projects to be constructed under public authority, and usually published in newspapers of general circulation in those districts from which the public funds are derived.

adytum, adyton 1. The inner shrine of a temple reserved for the priests. 2. The most sacred part of a place of worship.

adz A cutting tool whose thin arching blade is perpendicular to the handle; used for the rough-shaping of wood.

adze British term for adz.

A/E Abbr. for architect-engineer.

AEA Abbr. for “Aluminum Extruders Association.”

aedes 1. In Roman antiquity, any edifice or a minor shrine, not formally consecrated. 2. Now, any chapel or temple.

aedicula 1. A canopied niche flanked by colonnettes intended as a shelter for a statue or as a shrine. 2. A door or window framed by columns or pilasters and crowned with a pediment. 3. Diminutive of aedes. 4. A small chapel.

aegicranes Sculptured representations of the heads or skulls of goats or of rams; used as decorations on ancient altars, friezes, etc.

aerarium In ancient Rome, the public treasury.

aerate To introduce air into soil or water by natural or artificial means.

aerated concrete See cellular concrete.

aerated plastic Same as foamed plastic.

aeration 1. Exposing a substance to circulating air. 2. In landscape architecture, the addition of air into the soil; may be implemented by a plow-like mechanism or by the addition of an air-entrained material, such as vermiculite or peat moss, during the soil-conditioning process.

aerator fitting A device which introduces air into an exiting stream of water.

aerial cable An overhead electric cable (field-assembled at a construction site) which is attached to poles or other supporting structures.

aerial photograph, aerophoto A photograph taken from a vehicle in flight.

aerial photomap An aerial photograph or photomosaic to which is added basic mapping information such as place names, boundaries, etc.

aerial photomosaic A composite of aerial photographs depicting a portion of the earth’s surface.

aerodynamic noise Noise resulting from the flow of air; often generated in an air-conditioning system when an airstream encounters protuberances, rough surfaces, and/or blunt edges.

aerofilter A bed of coarse material used for the rapid filtering of sewage; recirculation of the effluent may be employed.

aerograph A spray gun for paint.

aerophoto An aerial photograph.

aerosol paints Paints which are packaged in a pressurized container for spray application. Pressure is supplied by compressed liquefied gas.

aes In ancient Rome or Greece: copper, tin, or any alloy of these metals.

aetoma, aetos A pediment, or the tympanum of a pediment.

A/F In a portland cement mixture, the abbr. for “molar or weight ratio of aluminum oxide to iron oxide.”

affronted, affronté Said of animals or figures facing each other, as in pediments, overdoors, etc.

AFNOR Abbr. for “Association Française de Normalisation.”

A-frame A three-piece rigid structural frame in the shape of the upright capital letter A.

A-frame house A house, usually constructed of wood, with a roof that extends steeply downward from both sides of a central ridge, almost to the building foundation; the roof is supported by a rigid structural framework in the shape of the capital letter A. One or both end walls of the house are often almost completely glazed. Much of the living area on the ground floor is open to the underside of the roof; the bedrooms are frequently located on a balcony directly under the roof; often, there is an exterior deck at one end or both ends of the house. Also see rafter house.

African cherry See makore.

African ebony See ebony.

African mahogany Same as khaya.

African rosewood See bubinga.

after cooler A device that cools compressed air after it is fully compressed.

afterfilter, final filter In an air-conditioning system, a high-efficiency filter located near a terminal unit.

afterflaming The continued flaming combustion of a material after the exposing flame has been removed.

after-flush The residue of water in a toilet flush tank after it has been flushed; after flushing, the residue gradually drains from the flush tank to seal the trap.

afterglow The glow in a material after the removal of an external source of fire to which it is exposed, or after the cessation (natural or induced) of flames.

aftertack, residual tack The lingering tack or stickiness of a paint film which remains over a long period of time.

AG 1. Abbr. for “above grade.” 2. Abbr. for “against the grain.”

AGA Abbr. for “American Gas Association.”

agalma In ancient Greece, any work of art dedicated to a god.

agba A large central African tree with rather lightweight wood of a creamy to pinkish brown color. Used for plywood, interior millwork, and carpentry.

AGC Abbr. for “Associated General Contractors.”

age hardening An aging process in certain metals, at room temperature, which results in increased strength and hardness.

ageing British variant of aging.

agency 1. A relationship by which one party, usually the agent, is empowered to enter into binding transactions affecting the legal rights of another party, usually called the principal, as, for example, entering into a contract or buying or selling property in his name or on his behalf. 2. An administrative branch of government (federal, state, or local).

agent One who is empowered to enter into binding transactions on behalf of another (usually called the principal).

age softening The loss of strength and hardness at room temperature which takes place in certain alloys owing to spontaneous reduction of residual stresses in the strainhardened structure.

agger 1. In ancient Rome, an earthwork; an artificial mound or rampart. 2. The fill for a road over low ground.

agglomerate stone See artificial stone.

agglomeration The collecting together of tiny suspended particles into a mass of larger size, one which will settle more rapidly.

AGGR On drawings, abbr. for aggregate.

aggradation The addition of a material to the earth’s surface to promote the uniformity of a grade or slope.

aggregate 1. An inert granular material such as natural sand, manufactured sand, gravel, crushed gravel, crushed stone, vermiculite, perlite, and air-cooled blast-furnace slag, which when bound together into a conglomerate mass by a matrix forms concrete or mortar. 2. An inert granular material that may be added to gypsum plaster.

aggregate bin A structure designed for storing and dispensing dry granular construction materials such as sand, crushed stone, and gravel; usually has a hopper-like bottom that funnels the material to a gate under the structure.

aggregate blending The mixing of two or more aggregates so as to obtain different aggregate properties.

aggregate interlock The projection of aggregate particles or portions thereof from one side of a joint or crack in concrete into recesses in the other side so as to effect load transfer in compression and shear, and maintain mutual alignment.

aggregate strength The strength of a wire rope determined by summing the individual breaking strength of the strands of which it is fabricated.

agiasterium In the early church, that part of a basilica in which the altar was set up.

aging, Brit. ageing 1. The progressive change in a chemical and physical material with increased age; in natural rubber and synthetic elastomers, usually marked by a deterioration caused by oxidation. Also see accelerated aging, age hardening, age softening. 2. The storing of varnish to improve clarity and gloss.

agitating lorry British term for agitating truck.

agitating speed The rate of rotation of the drum or blades of a truck mixer or other device used for agitation of mixed concrete.

agitating truck, Brit. agitating lorry A vehicle carrying a drum in which freshly mixed concrete can be conveyed from the point of mixing to that of placing, the drum being rotated continuously so as to agitate the contents.

agitation 1. The process of providing gentle motion in mixed concrete, just sufficient to prevent segregation or loss of plasticity. 2. The mixing and homogenization of slurries or finely ground powders by air or mechanical means.

agitator 1. A mechanical device used to mix a liquid contained in a vessel. 2. A device for maintaining plasticity and preventing segregation of mixed concrete by agitation.

agitator body A truck-mounted drum for transporting freshly mixed concrete; rotating internal paddles or rotation of the drum prevents the setting of the mixture prior to its delivery at the site.

AGL Abbr. for “above ground level.”

agnus dei Any image or representation of a lamb as emblematic of Christ, esp. such a representation with a halo and supporting the banner of the cross.

agora The chief meeting place or marketplace in an ancient Greek city.

agrafe, agraffe The voussoir or keystone of an arch, especially when carved as a cartouche.

agreement 1. A meeting of minds. 2. A legally enforceable promise or promises between two or among several persons. 3. On a construction project, the document stating the essential terms of the construction contract which incorporates by reference the other contract documents. 4. The document setting forth the terms of the contract between the architect and owner or between the architect and a consultant. 5. An arrangement indicating the intent of a contract but not necessarily fulfilling all the enforceable provisions of it. Also see agreement form, contract.

agreement form A document setting forth in printed form the general provisions of an agreement with spaces provided for insertion of specific data relating to a particular project.

Agrément Board See British Board of Agrément.

agricultural drain Same as agricultural pipe drain.

agricultural lime A hydrated lime which is used to condition soil.

agricultural pipe drain A system of porous or perforated pipes laid in a trench filled with gravel (or the like); used for draining subsoil.

aguilla An obelisk, or the spire of a church tower.

Ah Abbr. for “ampere-hour.”

aha Same as ha-ha.

AHU Abbr. for air-handling unit.

AIA Abbr. for “American Institute of Architects.”

AIA uniform system See contract documents and uniform system.

AIEE Abbr. for “American Institute of Electrical Engineers.”

aiguille A slender form of drill used for boring or drilling a blasthole in rock.

aileron A half gable, such as that which closes the end of a penthouse roof or of the aisle of a church.

AIMA Abbr. for “Acoustical and Insulating Materials Association.”

aiming angle Same as angle of illumination; usually measured in degrees.

air balancing A procedure used to adjust the flow of air in an HVAC system so as to meet the design goals for airflow throughout the system.

air barrier A membrane that acts as a resistance to air leakage.

air-blown mortar Same as shotcrete.

air blowpipe A pipe which emits a jet of air; used to clean an area of debris.

airborne sound Sound that reaches a point in a building by propagation from the source through air.

air-bound Said of a pipe or apparatus in which the presence of a pocket of air prevents or reduces the desired liquid flow in the pipe or apparatus. Also see air lock, 2.

air break In a drainage system, a piping arrangement in which a drain from an appliance, device, or fixture discharges into the open air and then into another fixture, receptacle, or interceptor; used to prevent back siphonage or backflow.

air brick A perforated brick or perforated metal unit of brick size which is built into a wall; used for ventilation.

airbrush A small tool used for the fine-spray application of paint, dye, watercolor pigment, or ink by compressed air.

air chamber In a water piping system near a valve or faucet, a vertical pipe stub which is sealed at the top and contains air; the entrapped air provides a cushion when the valve is closed suddenly, thereby eliminating the noise of water hammer.

air changes A measure of the volume of air supplied to or exhausted from a building (or room); usually expressed in terms of the number of complete changes of air per hour in the room or space under consideration.

air circuit breaker A type of circuit breaker utilized in commercial buildings at medium voltage; the word “air” refers to the insulating medium between contacts in the circuit breaker.

air circulation Natural or imparted motion of air.

air cleaner A device (such as an air washer, air filter, electrostatic precipitator, or charcoal filter) which removes airborne impurities such as dust, smoke, or fumes.

air cock Same as pet cock.

air compressor A machine which draws in air at atmospheric pressure, then compresses it to pressures higher than atmospheric and delivers it at a rate sufficient to operate pneumatic tools or equipment.

AIR COND On drawings, abbr. for “air condition.”

air conditioner A device for providing air conditioning.

air conditioning 1. The process of treating air so as to control simultaneously its temperature, humidity, cleanliness, and distribution within an interior space such as a room or building. 2. Same as definition 1, but also controlling odor and noise.

air-conditioning duct See air duct.

air-conditioning grille Same as inserted grille.

air-conditioning lock A type of window lock requiring a special key or wrench to open it; used where the window is to be opened only for special purposes, such as cleaning.

air-conditioning system An assembly of components for the treatment of air, controlling its temperature, humidity, cleanliness, and distribution within an air-conditioned space. Types of systems differ, but the basic components may include: outside-air intake, preheater, return-air intake, filters, dehumidifier, heating coil, humidifier, fans, ductwork, air outlets, air terminals, refrigeration machine, piping, pumps, and water or brine. See heating, ventilating, and air-conditioning system.

air-conditioning unit Same as room air conditioner.

air content The volume of air voids in cement paste, mortar, or concrete, exclusive of pore space in aggregate particles, usually expressed as a percentage of total volume of the mixture.

air control valve Same as air maintenance device.

air-cooled blast-furnace slag The material resulting from solidification of molten blast-furnace slag under atmospheric conditions. Also see blast-furnace slag.

air-cure To vulcanize at ordinary room temperatures, or without the aid of heat.

air cushion tank Same as expansion tank.

air curtain A stream of high-velocity temperature-controlled air which is directed downward, across an opening; excludes insects, exterior drafts, etc.; prevents the transfer of heat across it, and makes it possible to air-condition a space having an open entrance; used in exterior doors, on loading platforms, etc.

air damper See damper, 1.

air diffuser An air distribution outlet, usually located in the ceiling and consisting of deflecting vanes discharging supply air in various directions and planes, and arranged to promote mixing of the air which is supplied to the room with the air already in the room.

air-distributing acoustical ceiling A suspended acoustical ceiling in which the board, perforated metal, or tile is provided with small, evenly distributed mechanical perforations through the material; designed to provide a desired flow of air from a pressurized plenum above.

air door Same as air curtain.

air drain An empty space left around the external foundation wall of a building to prevent the earth from lying against it and causing dampness.

air-dried lumber, natural-seasoned lumber Wood dried by exposure to air under natural conditions; usually has a moisture content not greater than 24%.

air drill Same as pneumatic drill.

air-dry moisture content The moisture content of a piece of wood after it has been exposed to its environment long enough to attain moisture-content equilibrium without the application of heat.

air drying The process of drying slowly under ambient conditions of temperature and humidity, as in the natural seasoning of lumber or the hardening of paint.

air duct A duct, usually fabricated of metal, fiberglass, or concrete; used to transfer air from one location to another.

air eliminator In a piping system, a device used to remove air from water, steam, or a refrigerant.

air-entrained concrete Concrete made with air-entraining cement or an air-entraining agent. Same as cellular concrete.

air entraining Descriptive of the capability of a material or process to develop a system of minute bubbles of air in cement paste, concrete, or mortar.

air-entraining admixture An admixture that causes the development of air bubbles in concrete or mortar during its mixture.

air-entraining agent An addition for hydraulic cement or an admixture for concrete or mortar which causes air to be incorporated in the form of minute bubbles in the concrete or mortar during mixing, usually to increase its workability and frost resistance.

air-entraining hydraulic cement Hydraulic cement which contains an air-entraining agent in an amount such as to cause air to be entrained in the mortar, within specified limits.

air entrainment The occlusion of air in the form of tiny bubbles (generally smaller than 1 mm) during the mixing of concrete or mortar; used to improve its workability.

air exfiltration See exfiltration, 1.

air-exhaust ventilator 1. An air-exhaust unit used to carry away odors and fumes from a stove, griddle, etc.; may contain a grease-extracting device or an air filter; sometimes includes a fire-extinguishing device. 2. Any air-exhaust unit used to carry away dirt particles, odors, or fumes (as in an industrial plant); the ventilator may be mechanically actuated or of the gravity type.

air filter Any device used to remove solid and/or gaseous pollutants from air.

air filtration The use of an air filter to provide clean air.

airflow vane Same as turning vane.

air flue See flue.

airfoil vane Same as turning vane.

air-fuel ratio The ratio of the volume (or weight) of air being furnished for combustion to the volume (or weight) of the fuel.

air gap 1. The unobstructed vertical distance between the lowest opening of a faucet (or the like) which supplies a plumbing fixture (such as tank or wash bowl) and the level at which the fixture will overflow. 2. In a drainage system, the unobstructed vertical distance between the outlet of a waste pipe and the flood-level rim of the receptacle into which it discharges. 3. A gap in an electric or magnetic circuit; usually acts as a high-resistance path in the circuit.

air grating 1. A fixed metal grille on the exterior of a building through which air is brought into, or discharged from, the building for purposes of ventilation. 2. An air diffuser.

air grille A type of air grating.

air gun 1. Same as spray gun. 2. See shotcrete gun.

air hammer, pneumatic hammer A portable tool, driven percussively by air pressure, into which is set a chisel, hammer, or the like.

air-handling luminaire Same as air-light troffer.

air-handling system An air-conditioning system in which an air-handling unit provides part of the treatment of the air.

air-handling unit; packaged fan equipment An assembly of air-conditioning components (such as fans, cooling coils, filters, humidifiers, and dampers) integrated into a self-contained package and often installed as a single unit, which is connected to system of metal ductwork that distributes the conditioned air.

air heating system See warm-air heating system.

air hole In the foundation of a house, an opening that provides ventilation for a crawl space.

air house Same as pneumatic structure.

air-inflated structure Same as pneumatic structure.

air inlet In an air-conditioning system, a device through which air is supplied to the system.

air intake Same as outside-air intake.

air lance A rod-shaped device for directing a high-velocity stream of compressed air; used to clean away debris from a surface.

air leakage 1. The volume of air which flows through a closed window or door in a given length of time as a result of the difference in air pressure on its opposite faces. 2. In ductwork, air which escapes from a joint, coupling, etc. 3. The undesired leakage or uncontrolled passage of air from a ventilation system. 4. The flow of uncontrolled air through cracks or openings in an enclosure within a building (such as a HVAC plenum) or through the surfaces which enclose the building.

airless spraying, hydraulic spraying The spraying of paint by means of high fluid pressure and special equipment.

air lift 1. Equipment for lifting slurry or dry powder through pipes by means of compressed air. 2. The use of compressed air, introduced in water at the bottom of an open-ended cased pile or cell of a cofferdam, to rid it of loose material.

air-lift pump A type of pump for raising water from a well, consisting of a pipe which surrounds another of smaller diameter; compressed air is injected into the smaller pipe, causing water to rise up the larger pipe.

air-light troffer In an air-conditioning system, a unit which combines the functions of a light fixture and an air terminal unit.

air line A duct, hose, or pipe that supplies compressed air to a pneumatic tool or piece of equipment.

air lock 1. A space which is designed to isolate an air conditioned space from another space to which it is connected. 2. In a pump or piping system, the stoppage of flow resulting from the presence of trapped air. 3. An enclosure with control doors between two rooms that permits the ingress and egress from one room to another while permitting minimal air movement between rooms.

air-lock strip The weather stripping which is fastened to the edges of each wing of a revolving door.

air maintenance device A valve required to introduce air into a tank which stores water under pressure.

air meter A device for measuring the air content of concrete and mortar.

air-mixing plenum In an air-conditioning system, an enclosed volume in which recirculated air is mixed with fresh air for distribution throughout the system.

air monitoring During the removal of asbestos in buildings, the measurement of asbestos fiber content in the air.

air motor An air-operated device used to open or close a damper, 1 or valve.

air moving device See fan.

air outlet In an air-conditioning system, a device at the end of a duct through which air is exhausted.

air permeability test A test for the measurement of the fineness of powdered materials, such as portland cement.

air pipe A seldom-used synonym for vent pipe.

airplane bungalow A Craftsman style bungalow having a gable whose face is parallel to the main ridge of the roof; its second floor is a single room.

air pocket An air-filled volume within a section of piping (or an apparatus) which is normally filled with liquid.

air pressure-reducing valve See pressure-reducing valve.

air pressure relief vent A relief vent.

air pump A pump used to exhaust or to compress air, or force it through another apparatus. Also see air compressor.

air purge valve A device which eliminates trapped air from a piping system.

air quality See indoor air quality.

air receiver On an air compressor, the air storage tank.

air register Same as register.

air regulator A device for regulating airflow, as in the burner of a furnace.

air reheater In a heating system, any device used to add heat to the air circulating in the system.

air release valve A valve, usually manually operated, which is used to release air from a water pipe or fitting.

air right The legal property right for use of the space above a specified elevated plane; usually includes the right to ground support but excludes other rights to ground use, e.g., the right to construct a building over a railroad track.

air-ring In the placement of shotcrete, a perforated manifold through which air is introduced into the flow of material.

air scrubber See air washer.

air-seasoned lumber See air-dried lumber.

air separator An apparatus for separating ground-up materials pneumatically into various sizes.

air-set To allow material to harden under normal atmospheric pressure and temperature.

air shaft, air well A ventilating shaft; a roofless enclosed area within a building or between buildings; may have openings such as windows.

air shutter A device for regulating the quantity of air being mixed with gas for combustion.

air-slaked Said of a surface that is wetted by the exposure to moisture in air.

air slaking Absorption by quicklime or cement of moisture and carbon dioxide from the atmosphere, causing the material to change its chemical composition.

air space The space above private property or public property for which air rights may be granted.

air-supported structure See pneumatic structure.

air tap Same as air vent.

air terminal In a lightning protection system, the combination of a metal rod and its brace or footing, on the upper part of a structure.

air terminal unit In air-conditioning, same as terminal unit.

air test A test that applies uniform air pressure throughout a drainage system being tested for leakage. This test is recommended in lieu of a water test when there is a danger of water freezing during the test.

air test, pneumatic test A test for leaks in drainage systems, in soil, waste, and ventilating pipe systems, or in ductwork; all openings are sealed, and compressed air is introduced into the system; air leakage is indicated by means of a U-gauge or other suitable pressure gauge.

air tight Said of an enclosure or barrier that does not permit the passage of air.

air-to-air resistance The resistance provided by the wall of a building to the flow of heat. See thermal conductance and thermal resistance.

air-to-air transmission coefficient See thermal transmittance.

air trap Same as trap, 1.

air valve A valve used to admit or discharge air from a pipeline.

air vent In a water distribution system, a vent for releasing trapped air; usually located at the highest point in the system.

air ventilation The quantity of air which must be supplied to maintain the desired quality of air within a space.

air vessel 1. An enclosed volume of air which uses the compressibility of air to minimize water hammer. 2. An enclosed chamber using the compressibility of air to promote a more uniform flow of water in a piping system.

air void A space which is filled with air in cement paste, mortar, or concrete. Also see entrapped air, entrained air.

air washer A water spray system or device for cleaning, humidifying, or dehumidifying the air.

air-water jet 1. A jet of air and water mixed, which leaves a nozzle at high velocity; used in cleaning the surfaces of concrete or rock. 2. In cleaning concrete or rock surfaces, a high-velocity jet consisting of a mixture of air and water.

air-water storage tank A water storage tank in which the air, above the water, is compressed.

airway A passage for ventilation between thermal insulation and roof boards.

air well See air shaft.

AISC Abbr. for “American Institute of Steel Construction.”

AISI Abbr. for “American Iron and Steel Institute.”

aisle 1. A longitudinal passage between sections of seats in an auditorium or church. 2. In a church, the space flanking and parallel to the nave; usually separated from it by columns, intended primarily for circulation but sometimes containing seats.

aisle access way A continuous, unobstructed accessible route around seating, furniture, or desks so as to provide adequate clearance for the disabled.

aisleway A passage or walkway within a factory, storage building, or shop permitting the flow of inside traffic. Also see aisle.

AITC Abbr. for “American Institute of Timber Construction.”

aiwan A reception hall in an ancient Parthian building.

ajaraca In southern Spain, an ornament in brick walls, formed of patterns, a half brick deep, more or less complicated.

a jour, ajouré Pierced, perforated, or cut out to form a decorative opening in wood, stone, metal, or other material.

AL On drawings, abbr. for aluminum.

ala 1. An alcove or small room opening off the atrium of an ancient Roman house. 2. A small room on each side of a cella.

alabaster Fine-grained, translucent variety of very pure gypsum, generally white or delicately shaded.

A-labeled door A door carrying a certification from the Underwriters’ Laboratories, Inc. that it meets the requirements for a class-A door.

alameda A shaded public walk or promenade.

alarm system An electrical system that is installed in a building as a protective measure against fire or unauthorized entry. In the event that the system is activated, an alarm (such as an audible signal or flashing light) is turned on; see fire alarm system and burglar alarm system.

alarm valve See wet alarm valve.

alatorium 1. A piazza, corridor, or covered walk. 2. The flank of a building.

albani stone A pepper-colored stone used in buildings in ancient Rome before the introduction of marble.

albarium A white lime used for stucco; made by burning marble.

albronze Same as aluminum bronze.

album In ancient Roman architecture, a space on the surface of a wall covered with white plaster, located in a public place, on which public announcements and records, etc. were written.

alburnum Same as sapwood.

alcazar A Moorish or Spanish fortress or castle.

alclad A metal product clad with an aluminum or aluminum-alloy coating, usually as a protection against corrosion.

alcove A small recessed space, opening directly into a larger room.

alder A moderately light-colored, light-weight hardwood that changes to flesh color or light brown when dried; often stained to simulate cherry, mahogany or walnut; often used as plywood core and crossbanding.

aleatorium In ancient Roman architecture, a room in which dice games were played.

ale house In an early British or American community: a village tavern licensed to sell alcoholic beverages.

alette 1. A minor wing of a building. 2. A door jamb. 3. A rear pilaster, partially visible within a cluster of columnar elements. 4. The wing of the pier on both sides of an engaged column.

Alexandrian work Same as opus Alexandrinum.

Alexandrinum opus Same as opus Alexandrinum.

alfiz A decorative molding enclosing a door or arch.

Alhambra A fortress and palace built by the Moorish kings of Granada in southern Spain, completed in the 14th century.

Alhambresque Ornamentation that resembles the fanciful style used at the Alhambra.

alicatado Tile work which is executed with azulejos; used to decorate pavements and walls, especially in patios.

alidade The part of a surveying instrument which consists of a sighting device, with index, and reading or recording accessories.

alienation The transfer of title to real property by one person to another.

aliform Having a wing-like shape or extensions.

aligning punch A punch used for lining up mating holes prior to riveting or bolting; a drift punch.

alignment 1. An adjustment in a straight line. 2. The theoretical, definitive lines that establish the position of construction (such as a building) or the shape of an individual element (such as a curved or straight beam). 3. In highway and other surveys, the ground plan depicting direction of the route as distinguished from a profile, which shows the vertical element. 4. In prehistoric building, formal alleys of standing stones, as at Carnac in France.

alipterion In ancient Roman architecture, a room used by bathers for anointing themselves.

alite A principal constituent of portland-cement clinker; primarily tricalcium silicate, but includes small amounts of magnesium oxide, aluminum oxide, ferric oxide, and other oxides.

alive Same as live, 1.

alkali Any of the various chemically active bases such as the soluble salts of metals, e.g., the water-soluble salts of sodium and potassium which occur in constituents of concrete and mortar that may result in deleterious expansion.

alkali-aggregate reaction A chemical reaction in mortar or concrete between alkalies from portland cement or other sources and certain constituents of some aggregates; under certain conditions, deleterious expansion of the concrete or mortar may result.

alkalinity See pH.

alkaline soil Soil containing soluble salts of magnesium, sodium, or the like, and having a pH value of between 7.3 and 8.5.

alkali reactivity Of a concrete aggregate, its susceptibility to alkali-aggregate reaction.

alkali resistance 1. The degree to which a paint resists reaction with alkaline materials such as lime, cement, plaster, soap, etc.; a necessary property for paints in bathrooms, kitchens, laundries. 2. The degree to which a porcelain enamel will resist attack by aqueous alkaline solutions.

alkali-silica reaction In portland cement, the reaction between the alkalies and particular siliceous rocks and/or minerals which are present in some aggregates; may result in abnormal expansion and cracking of concrete under service conditions.

alkali soil A soil, with salts injurious to plant life, having a pH value of 8.5 or higher.

alkyd paint A paint using an alkyd resin as the vehicle for the pigment.

alkyd resin One of a group of thermoplastic synthetic resins; used in bonding materials, in adhesives, and in paints and varnishes.

allée A broad walk, planted with trees on either side, usually at least twice as high as the width of the walk.

allège A part of a wall which is thinner than the rest, esp. the spandrel under a window.

allegory A figurative representation in which the meaning is conveyed symbolically.

Allen head A screw having a hexagonally shaped recess in its head.

Allen wrench A wrench for Allen head screws; a steel bar, hexagonal in shape, which is bent to form a right angle.

alley 1. A service way providing a secondary public means of access to abutting properties; a narrow passageway between or behind buildings, sometimes permitting traffic for only one lane of cars. 2. A garden walk between rows of trees; an allée.

all-heart lumber Lumber that is all heart-wood, entirely free of sapwood.

alligator hide A surface condition on porcelain enamel, characterized by an extreme roughness; a severe case of orange peel.

alligatoring 1. The splitting of a film of paint in a pattern resembling an alligator skin, caused by shrinkage of a coat of paint applied over a semiplastic or thermoplastic undercoat; also called crocodiling. 2. Surface cracking, due to oxidation and shrinkage stresses, which shows as repetitive mounding of an asphalt surface in a pattern resembling the hide of an alligator; occurs only in unsurfaced bitumen exposed to the weather.

alligator shears, lever shears Wide-jawed shears, resembling the jaws of an alligator, used to cut sheets of metal; operated by a foot lever.

alligator wrench A wrench having V-shaped, fixed serrated jaws; used to turn cylindrical parts, esp. in fitting pipe.

all-in aggregate See bank-run gravel.

all-in contract Same as turn-key job.

allotment garden Any privately or publicly owned garden area which has been divided into plots for assignment to individuals for their use.

allover A pattern covering an entire surface; usually one which is repeated.

ALLOW. On drawings, abbr. for “allowance.”

allowable bearing value, allowable soil pressure, allowable bearing capacity The maximum permissible pressure on foundation soil that provides adequate safety against rupture of the soil mass or movement of the foundation of such magnitude as to impair the structure that imposes the pressure.

allowable load The load which induces the maximum permissible unit stress at a critical section of a structural member.

allowable pile bearing load The maximum permissible load on a pile that provides adequate safety against movement of such magnitude that would endanger the structure supported by the pile.

allowable pile load The allowable concentrically applied load which is permitted along the central axis of a pile.

allowable soil pressure See allowable bearing value.

allowable stress In the design of structures, the maximum unit stress permitted under working loads by codes and specifications.

allowance 1. See cash allowance. 2. See contingency allowance.

alloy A composition of two or more metals fused together, usually to obtain a desired property.

alloy steel Steel containing one or more alloying elements other than carbon, such as chromium, molybdenum, or nickel, which have been added (in an amount exceeding a specified minimum) to impart particular physical, mechanical, or chemical properties.

all-risk insurance On a construction project, insurance that protects the policyholder against all risks other than those which are specifically excluded by the policy.

all-rowlock wall See rowlock cavity wall.

all-stretcher bond A masonry bond, 6 showing only stretchers on the face of the brick wall; same as stretcher bond.

allure See alure.

alluvial deposit Earth, sand, gravel, or other rock or mineral materials transported and laid down by flowing water.

alluvium Gravel, sand, silt, soil, or other material that is deposited by running water.

ALM On drawings, abbr. for “alarm.”

almariol A storage place for ecclesiastical vestments; an ambry.

almary See ambry.

almehrabh In Arabian architecture, a niche in a mosque which marks the direction of Mecca.

almemar, almemor 1. A bema, 2. 2. In a synagogue, a desk on which the Torah is placed while being read to the congregation.

almena An indented trapezium serving as an embattled parapet. (See illustration p. 28.)

almery See ambry.

almocarabe Same as ajaraca.

almond An aureole of elliptical form.

almonry A building or part thereof where alms are distributed.

almorie Same as almariol.

almorrefa In Hispanic architecture, brickwork intermixed with azulejos; used as flooring.

almshouse 1. A building in which charity was distributed to the poor; found in England and in some early American settlements and cities; also see poorhouse. 2. An almonry.

alpha brass An alloy containing 51 to 61% copper and 39 to 45% zinc; used in hot-water systems because of its corrosion resistant properties.

alpha gypsum A specially processed gypsum having low consistency and high compressive strength, often exceeding 5,000 lb per sq in. (352 kg per sq cm).

ALS Abbr. for “American Lumber Standards.”

ALT On drawings, abbr. for “alternate.”

altana A light ornamental structure on a roof that serves much the same function as a gazebo.

altar 1. An elevated table, slab, or structure, often of stone, rectangular or round, for religious rites, sacrifices, or offerings. 2. The Communion table in certain churches.

altar frontal An ornamental hanging or panel for the front of an altar.

altar of repose In a Roman Catholic church, a side altar, repository, or storage niche where the Host is kept from Maundy Thursday to Good Friday.

altarpiece A decorative screen, painting, or sculpture above the back of an altar.

altar rail A low rail or barrier in front of the altar, running transversely to the main axis of the church and separating the officiating clergy from the other worshipers.

altar screen A richly decorated partition of stone, wood, or metal, separating the altar from the space behind it.

altar slab, altar stone A flat stone or slab forming the top of an altar.

altar tomb A raised tomb, or monument covering a tomb, whose shape resembles an altar.

alteration Construction in a building which may change the structural parts, mechanical equipment, or location of openings, but does not increase the overall area of dimensions of the building.

alterations 1. A construction project (or portion of a project) comprising revisions within or to prescribed elements of an existing structure, as distinct from additions to an existing structure. 2. Remodeling.

alternate A change in work, 1 described in the contract documents for a building that gives the owner the option of selecting various products, materials, or systems, and/or the right to add or delete portions of the work, 1.

alternate bid The amount stated in the bid to be added to or deducted from the amount of the base bid if the corresponding change in project scope or alternate materials and/or methods of construction is accepted.

alternating current An electric current that varies periodically in value and direction, first flowing in one direction in the circuit and then flowing in the opposite direction; each complete repetition is called a cycle, and the number of repetitions per second is called the frequency; usually expressed in Hertz (Hz).

alternating Flemish bond A brickwork pattern which is produced by laying alternate courses of Flemish bond and common bond.

alternating sprinkler system A fire sprinkler system that can be changed from a wet-pipe sprinkler system in the summer to a dry-pipe sprinkler system in the winter.

alternator A generator of alternating current which is produced by the turning of its rotor.

ALTN On drawings, abbr. for “alteration.”

alto-rilievo, alto-relievo See high relief.

alum A chemical compound added to gypsum plaster to make the plaster harden faster.

ALUM. On drawings, abbr. for aluminum.

alumina The oxide of aluminum; an important constituent of the clays used in brick, tile, and refractories.

aluminium British term for aluminum.

aluminize, Brit. aluminise To apply a surface coating of aluminum to another metal or other base material, usually by spraying or dipping in molten aluminum. On steel, such coatings greatly increase corrosion resistance.

aluminous cement See calcium aluminate cement.

aluminum, Brit. aluminium A lustrous, silver-white, nonmagnetic, lightweight metal which is very malleable; has good thermal and electrical conductivity; a good reflector of both heat and light. In construction, most aluminum is used in alloy form because of added strength; further strengthened by heat treatment; used in extrusions, castings, and sheets. Excellent resistance to oxidation; often anodized for better corrosion resistance, surface hardness, and/or architectural color requirements.

aluminum brass Brass to which aluminum has been added to increase its corrosion resistance.

aluminum bronze A copper-aluminum alloy, usually with 3 to 11% aluminum; may contain additional additives; has good corrosion resistance and may be cast or coldworked.

aluminum door A door having aluminum stiles and rails; usually glazed.

aluminum foil Very thin aluminum sheet (less than 0.006 in. or 0.15 mm); usually used for thermal insulation and vapor barriers.

aluminum oxide Same as alumina.

aluminum paint A paint made with aluminum paste and a film-forming vehicle (such as a varnish); a good heat and light reflector; has good water impermeability.

aluminum powder Small flakes of aluminum metal obtained by stamping or ball-milling foil in the presence of a fatty lubricant, such as stearic acid, which causes the flakes to orient in a pattern to give high brilliance. Usually supplied in paste form wetted with mineral spirits.

aluminum primer An aluminum-based primer, 1 that has excellent water-resistant properties.

aluminum-silicon bronze An alloy consisting chiefly of copper with aluminum and silicon added to give it greater strength and hardness.

aluminum window Any window constructed principally of aluminum, the components of which usually are extruded.

aluminum-zinc coating On a metal surface, a corrosion-resistant coating having properties similar to galvanizing.

alure, allure, alur A gallery or passage, as along the parapets of a castle, around the roof of a church, or along a cloister.

ALV Symbol for alarm valve.

alveated Having the vaulted shape of a beehive.

alveus In ancient Rome, a bath constructed in the floor of a room, the upper part of it projecting above the floor, the lower part being sunk into the floor itself.

ALY On drawings, abbr. for alloy.

amado In traditional Japanese architecture, a type of shutter made of sliding wooden panels which (when not in use) slide into a box-like storage cabinet attached to the exterior of the building at one side of the opening; usually set in place in the evening.

AMB Abbr. for “asbestos mill-cut board.”

ambient lighting In any given area, the general background illumination.

ambient noise The all-encompassing, average background noise associated with a given environment, often a composite of sounds from many sources near and far, of many different types, e.g., the general background noise in a neighborhood or in an auditorium.

ambient pressure In a water distribution system, the normal operating pressure at any particular location in the system.

ambient temperature The temperature of the surrounding air.

ambitus 1. A small niche in underground Roman or Greek tombs, forming a receptacle for a cinerary urn. 2. In the Middle Ages, such a niche, but enlarged to admit a coffin. 3. In the Middle Ages, the consecrated ground surrounding a church.

ambo, ambon 1. In early Christian churches, a pulpit for reading or chanting the Gospels or the Epistles. 2. In contemporary Balkan or Greek churches, a large pulpit or reading desk.

ambrices In ancient Roman construction, the cross laths inserted between the rafter and tiles of a roof.

ambry, almary, almery, aumbry 1. A cupboard or niche in a chancel wall for the utensils of the Eucharist; an armarium. 2. A storage place, storeroom, closet, or pantry.

ambulatory 1. A passageway around the apse of a church, or for circumambulating a shrine. 2. A covered walk of a cloister.

ambulatory church A church having a domed center bay which is surrounded on three sides by aisles.

AMCA Abbr. for “Air Movement and Control Association.”

AMD On drawings, abbr. for “air-moving device.”

amended water Water to which a surfactant has been added.

amendment A modification to a building’s contract documents.

American basement A floor of a building partly above and partly below grade level, often serving as the entrance level to the building. Also see basement. Also called a walk-out basement.

American bond Same as common bond; same as English garden-wall bond.

American Bracketed style A term occasionally used for the Italianate style.

American Chateauesque style See Chateauesque style.

American Colonial architecture A term usually applied to colonial buildings constructed in America by English immigrants to the New World; often classified according to region in America.

In early colonial New England, the typical house was timber-framed with hewn-and-pegged joints; exterior walls were sometimes covered with hard plaster, then clad with clapboard or weatherboards. Unpretentious houses commonly had a single room with a loft space above; more prosperous houses, often one and a half or two stories high and one or two rooms deep, usually were built on the hall-and-parlor plan, with one room on each side of an interior wall containing a massive, centrally located fireplace and a large high chimney; on the façade, drops were often suspended from the underside of an overhanging second floor. Many of these early houses had a steeply pitched gable roof and a side gable, or a hipped roof with eaves having no significant overhang; unglazed window openings were covered with solid-wood shutters, later replaced by narrow casement windows having small quarrels; heavy battened doors. Also see saltbox house, stone ender, whale house. Occasionally called Early Colonial architecture.

In the colonial South and along the mid-Atlantic coast, single-room houses of the early settlers were often similar to the one-room plan houses in New England, with a clay-and-sticks chimney. Later, as the houses became larger, they usually followed a hall-and-parlor plan or a center-hall plan. Exterior walls were usually brick, with hand-split shingles on the roof; a massive decorative brick or stone exterior chimney at one or both gabled end walls, with corbeled chimney caps. Pent roofs were common in the mid-Atlantic area. For colonial architecture constructed by immigrants other than the English, see Dutch Colonial architecture, French Colonial architecture, German Colonial architecture, Spanish Colonial architecture.

American Colonial Revival An architecttural mode usually based on architectural prototypes in the English colonies in America, but often including features not found or rarely present in those prototypes. Buildings in this classification are usually characterized by a façade often featuring a Classical cornice; cupola; widow’s walk; colonial detailing; bevel siding or a smooth brick wall finish with fine joints; brickwork often set in a Flemish bond pattern; splayed lintels; a hipped, gabled, or gambrel roof covered with slate tiles or wood shingles; louvered shutters; double-hung rectangular sash windows with multiple panes in both the upper and lower sashes; symmetrically arrayed windows in the façade; a fanlight over the main entry door and sidelights on each side of door; the front door commonly crowned by a pediment, extending forward and supported on columns so as to form an entry porch.

American four-square house 1. A one- or two-story house having a square floor plan consisting of four rooms (one in each corner), a hipped roof, and an off-center entry door; most popular from about 1905 to 1915. 2. A Prairie box, primarily in the years between about 1900 to 1920, having a low-pitched hipped roof and a symmetrical façade.

American Institute of Architects (AIA) A professional organization, founded in 1857, whose purpose is to establish and promote professionalism and accountability on the part of its members, and to promote architectural design excellence. Address: 1735 New York Avenue NW, Washington, DC 20006.

American International style See International style and Contemporary style.

American linden See basswood.

American Mansard style A seldom-used synonym for Second Empire style. Also see Mansard style.

American method of application A method of applying rectangular roofing shingles which provides double coverage with a head lap, but no side lap.

American National Standards Institute An independent organization of trade associations, technical societies, professional groups, and consumer organizations; establishes and publishes standards; formerly known as the United States of America Standards Institute (USASI or ASI), and previously as the American Standards Association (ASA).

American oriental carpeting An American loom-made carpet, of Axminster or Wilton weave, manufactured in color and pattern designs similar to those of oriental rugs.

American Renaissance Revival A term occasionally used for Italian Renaissance Revival.

American Rundbogenstil Same as Round Arch style.

American Society of Landscape Architects (ASLA) The professional organization of landscape architects in America, founded in 1899. Address: 636 Eye Street, NW, Washington, DC 20008.

American Society for Testing and Materials A nonprofit organization that establishes standard tests and specifications for construction materials; such tests and specifications usually are referred to by the abbreviation ASTM followed by a numerical designation. Address: 100 Bar Harbor Drive, West Conshohocken, PA 19428.

American standard beam A type of I-beam of hot-rolled structural steel; designated by the prefix S placed before the size of the member.

American standard channel A C-shaped structural member of hot-rolled structural steel; designated by the prefix C placed before the size of the member.

American standard pipe threads In the US, standard pipe threads for commonly used sizes of pipe for water, gas, or steam; formerly called Briggs standard pipe threads.

American Standards Association See American National Standards Institute.

Americans with Disabilities Act (ADA) A federal law, enacted in 1990, requiring that public accommodations be accessible to those having physical disabilities; this law mandates that existing physical barriers be replaced or modified so there are no impediments to access by the physically disabled. For detailed information, write the US Equal Employment Opportunities Commission, 1801 L Street, NW, Washington, DC 20507. See American National Standards Institute (ANSI) Standard A117.1-1992. Also see Uniform Federal Accessibility Standards and physical disability.

American table of distances A table giving safe distances for the storage of explosives, as approved by the Institute of the Makers of Explosives.

American Tudor style See Tudor Revival.

American wire gauge, American standard wire gauge, Brown and Sharpe gauge A system used in the US for designating wire diameter in electrical wiring or the thickness of aluminum, brass, and copper sheets; ranges from 6/0 (0.58 in. or 16.3 mm) to 40 (0.0031 in. or 0.079 mm).

Amer Std Abbr. for “American Standard.”

amino plastic Any plastic made of compounds derived from ammonia.

ammeter An instrument for measuring the rate of flow of electricity, usually expressed in amperes.

ammonia A chemical used as a refrigerant, esp. in large low-temperature refrigeration systems (as in ice skating rinks) because of its high efficiency.

ammonium chloride See sal ammoniac.

amoretto, amorino Same as cupid.

amorini Same as putti.

amorino, amoretto A winged cherub.

amorphous Said of rock having no crystal structure.

amortizement The sloping top of a buttress or projecting pier.

amount of mixing The designation of the extent of mixer action employed in combining the ingredients for concrete or mortar; for stationary mixers: the mixing time; for truck mixers: the number of revolutions of the drum or blades at mixing speed, after the intermingling of the cement with water and aggregates.

amp Abbr. for ampere.

ampacity The current-carrying capacity of a wire or cable, expressed in amperes.

amperage The flow of electric current in a circuit, expressed in amperes.

ampere The International Standard unit for electrical current. A unit of the rate of flow of electric current; an electromotive force of 1 volt acting across a resistance of 1 ohm results in a current flow of 1 ampere.

amphiprostyle Marked by columns in porticoes only at the front and back (of a classical temple), not on the sides.

amphistylar Said of a classical temple having columns across the length of both sides or across both ends.

amphitheater, amphitheater 1. A circular, semicircular, or elliptical auditorium in which a central arena is surrounded by rising tiers of seats. 2. (Brit.) The first section of seats in the gallery of a theater. 3. Any outdoor theater, esp. of the classical Greek type.

amphithura A curtain divided in the center, closing the entrance through the iconostasis of a Greek church.

amplitude Of oscillation or vibration, the maximum displacement from the mean position.

amusement park A commercially operated park with entertainment features such as roller coasters, shooting galleries, merry-go-rounds, refreshment stands, etc.

amyl acetate, banana oil A solvent for lacquers and paints; has a strong banana-like odor.

amylin See dextrin.

anaglyph An embellishment carved or chased in low relief. Also see bas-relief.

analemma 1. A retaining wall at the side of an ancient Greek or Roman theater. 2. Any raised construction which serves as a support or rest.

analogion, analogium 1. A reading desk, lectern, or ambo. 2. In the Eastern church, a stand on which choir books rest.

anamorphosis A drawing which appears to be distorted unless viewed from a particular angle or with a special device.

anatase See titanium dioxide.

anathyrosis A Greek method of fitting masonry without mortar by carefully dressing the contact edges of the blocks, leaving the center rough and slightly recessed.

anchor, anchorage 1. A device such as a metal rod, wire, or strap, for fixing one object to another, as specially formed metal connectors used to fasten together timbers, masonry, trusses, etc. 2. In prestressed concrete, a device to lock the stressed tendon in position so that it will retain its stressed condition. 3. In precast concrete construction, a device used to attach the precast units to the building frame. 4. In slabs on grade, or walls, a device used to fasten to rock or adjacent structures to prevent movement of the slab or wall with respect to the foundation, adjacent structure, or rock. 5. A support which holds one end of a timber fast. 6. A device used to secure a window or doorframe to the building structure; usually adjustable in three dimensions; also see doorframe anchor. 7. See jamb anchor, masonry anchor, etc. 8. The anchor-shaped dart in the egg-and-dart molding; also called anchor dart. 9. A device used in a piping system to secure the piping to a structure; typically provided by a metal insert in an overhead concrete slab or beam. 10. A wrought-iron clamp, of Flemish origin, on the exterior side of a brick building wall that is connected to the opposite wall by a steel tie-rod to prevent the two walls from spreading apart; these clamps were often in the shape of numerals indicating the year of construction, or letters representing the owner’s initials, or were simply fanciful designs.

anchor beam In a typical Dutch barn in colonial America, a massive horizontal timber that spans the barn from one gable end to the opposite end.

anchorage 1. In posttensioning, a device which anchors the tendons to the posttensioned concrete member. 2. In pretensioning, a device used to anchor the tendons temporarily during the hardening of the concrete. 3. Same as anchor, 3.

anchorage bond stress The forces in a steel bar divided by the product of the perimeter and the embedment length.

anchorage deformation, anchorage slip The shortening of tendons in prestressed concrete due to the deformation of the anchorage or slippage of the tendons in the anchorage device when the prestressing force is transferred to the anchorage device.

anchorage device Any device used in anchorage.

anchorage loss Same as anchorage deformation.

anchorage system A group of interacting anchors and elements.

anchorage zone 1. In posttensioning, the region adjacent to the anchorage for the tendon which is subjected to secondary stresses as a result of the distribution of the prestressing force. 2. In pretensioning, the region in which transfer bond stresses are developed.

anchor block A block of wood, replacing a brick in a wall to provide a nailing or fastening surface.

anchor bolt, foundation bolt, hold-down bolt 1. A steel bolt usually fixed in a building structure with its threaded portion projecting; used to secure frameworks, timbers, machinery bases, etc. 2. See brick anchor.

anchor cable A cable or line, one end of which is held in a fixed position.

anchor dart See anchor, 8.

anchor fastener A mechanical device (such as a bolt or spike) used to secure a timber or wood framework.

anchored-type ceramic veneer Ceramic veneer which is attached to a backing by grout and nonferrous metal anchors; minimum overall thickness is 1 in. (2.54 cm).

anchor iron Same as beam anchor.

anchor line Same as anchor cable.

anchor log A timber which serves as a dead man.

anchor pile A pile behind a retaining wall to which tie-back rods or cables are connected.

anchor plate A square metal plate used as floor tile in industrial plants.

anchor rod A threaded metal rod used with various types of hangers to support ductwork, piping, etc.

anchor store A store (usually a major chain store or department store) in a shopping center or mall whose presence attracts business to smaller shops within the center.

anchor tie Same as anchor, 1.

ancient light (Brit.) A window which is legally entitled to the continuous access to light by virtue of having had continuous access to light for many years in the past.

ancillary One of a group of buildings having a secondary or dependent use, such as an annex.

ancon, (pl.) ancones 1. A scrolled bracket or console, 1 which supports a cornice or entablature over a door or window. 2. A projecting boss on a column drum or wall block. 3. A cramp to fasten blocks of stone.

anda The hemispherical dome of a stupa.

andiron One of a pair of metal supports for a log in a fireplace.

andron, andronitis 1. In ancient Greece, the part of a building used by men, esp. the banquet room. 2. A passage beside the tablinum in a Roman house.

anechoic room A room whose boundaries absorb almost completely sound waves which are incident upon them; practically no sound is reflected from the boundaries.

anemometer An instrument for measuring the velocity of airflow.

angel beam A hammer beam of a medieval roof truss; so called because it often had an angel carved on its surface.

angel light A small triangular light, 1 between subordinate arches of the tracery of a window, esp. in the English Perpendicular style.

angiosperm A class of seed plants (having seeds enclosed in an ovary) which includes most of the world’s flowering plants.

angiportus In ancient Rome, a narrow road passing between two houses or a row of houses, or an alley leading to a single house.

angle 1. The figure made by two lines that meet. 2. The difference in direction of such intersecting lines, or the space within them. 3. A projecting or sharp corner. 4. A secluded area resembling a corner; a nook. 5. An L-shaped metal member; an angle iron. 6. See bevel angle. 7. A fitting on a gutter for rainwater which changes the gutter’s direction.

angle bar 1. An upright bar at the meeting of two faces of a polygonal window, bay window, or bow window. 2. An angle iron.

angle bead 1. A corner bead. 2. A strip, usually of metal or wood, set at the corner of a plaster wall to protect the corner or serve as a guide to float the plaster flush with it; a type of angle staff.

angle blasting Sandblasting, or the like, at an angle of less than 90°.

angle block, glue block A small block of wood, triangular in cross section, which is used to stiffen two intersecting pieces of wood at right angles; for example, under the step of a stair.

angle board A board whose surface is cut at a desired angle; serves as a guide for cutting and/or planing other boards at the same angle.

angle bond A tie used to bond masonry work at wall corners.

angle brace 1. A strip of material which is fixed across a frame to make it rigid, as a wood strip which is nailed temporarily across the corners of a window frame or doorframe to maintain squareness during shipment or in handling before permanent installation; also called an angle tie. 2. An angle iron. 3. A special brace which is used for drilling where there is insufficient room for an ordinary brace handle to turn.

angle bracket A projecting bracket which is not at right angles to the wall.

angle brick Any brick having an oblique shape to fit an oblique, salient corner.

angle buttress One of two buttresses at right angles to each other, forming the corner of a structure.

angle capital A capital at a corner column, esp. an Ionic capital where the four volutes project equally on the diagonals, instead of being in two parallel planes; used by both Greeks and Romans.

angle chimney A chimney placed so that the sides of the chimney form an angle with the side walls of a room.

angle cleat Same as angle clip.

angle clip A short strip of angle iron used to secure structural elements at right angles.

angle closer A special-shaped brick used to close the bond at the corner of a wall.

angle collar A cast-iron pipe fitting which has a socket at each end for joining with the spigot ends of two pipes that are not in alignment.

angle column A column placed at the corner of a building, as at the corner of a portico; may be freestanding or engaged.

angle corbel An L-shaped corbel plate forming a right-angle bend, the vertical surface of which is fastened to the wall; the horizontal surface is used to support a building component.

angled bay window A bay window that is triangular in plan and protrudes outward from a wall.

angled chimney stacks See diagonal chimney stacks.

angle divider A square for setting or bisecting angles; one side is an adjustable hinged blade; when set at 90°, it can be used as a try square.

angle dozer A bulldozer with its blade set at an angle to push the earth to one side.

angledozer Same as bulldozer.

angled stair A stair whose successive flights are at an angle other than 180° to each other (often the angles are at 90°), with an intermediate platform between them.

angle fillet A wooden strip, triangular in cross section, which is used to cover the internal joint between two surfaces meeting at an angle of less than 180°.

angle fireplace A fireplace across one corner of a room; for example, see fogón.

angle float A trowel having two edge surfaces bent at 90°; used to finish corners in freshly poured concrete and in plastering. (See illustration p. 38.)

angle gauge A template used to set or check angles in building construction.

angle globe valve A type of globe valve intended for use at a point in a water distribution system where the piping changes direction by 90°; saves the cost of an extra elbow and provides an additional point of control of water flow.

angle hip tile An arris hip tile.

angle iron, angle bar An L-shaped iron or steel bar or structural steel member.

angle joint A joint between two pieces of lumber which results in a change in direction, such as a dovetail joint or a mortise-and-tenon joint.

angle lacing A system of lacing in which angle irons are used in place of bars.

angle leaf In medieval architecture, a carved claw or spur, 1 which projects from the lower torus of a column, so as to cover one of the projecting corners of the square plinth beneath.

angle-lighting luminaire A luminaire whose light distribution is asymmetric with respect to a direction of specific interest.

angle modillion A modillion at the corner of a cornice.

angle newel A landing newel.

angle niche A niche formed at the corner of a building; common in medieval architecture.

angle of illumination The angle between the axis of an illuminator and a perpendicular to the surface being illuminated.

angle of repose The maximum angle with the horizontal at which a mass of material, as in a cut or embankment, will lie without sliding; the angle between the horizontal and the maximum slope that a soil assumes through natural processes.

angle of rest Same as angle of repose.

angle paddle A hand tool used to finish a plastered surface.

angle pier A pier, 2 at the intersection of two walls, constructed on the external angle.

angle post In half-timber construction, the corner post.

angle rafter A hip rafter.

angle rail A timber that is cut from a square rail to form two lengthwise pieces which are triangular in cross section.

angle rib 1. In decorative work, a molding that ornaments an angle. 2. In Gothic architecture, one of the diagonal ribs, 1 that divides each of the rectangles of a vault.

angle ridge A hip rafter.

angle-roll Same as bowtell.

angle section A structural steel member having an L-shaped cross section.

angle shaft 1. A column within the right-angled recesses of Norman door and window jambs. 2. A decorative member, such as a colonnette or enriched corner bead, attached to an external angle of a building.

angle staff, staff angle A vertical strip of wood or metal at the exterior angle of two plastered surfaces and flush with them; protects the plastering and serves as a guide for floating the plaster; a corner bead, 2.

angle stile A narrow strip of wood used to conceal the joint between a wall and a vertical wood surface which makes an angle with the wall, as at the edge of a corner cabinet.

angle stone Same as quoin.

angle strut An angle-shaped structural member which is designed to carry a compression load.

anglet A groove, usually containing an angle of 90°.

angle tie See angle brace, 1.

angle tile A tile, 1 that forms an angle; used to cover a hip, 1 (ridge) of a roof; sometimes used in weather tiling (tile hanging) to cover the corner of a building.

angle trowel A margin trowel.

angle valve A valve for controlling the flow of a liquid or air; the fluid leaves at right angles to the direction in which it enters the valve.

angle volute See angle capital.

Anglo-Italian Villa style A term occasionally used for the Italianate style.

Anglo-Palladianism An architectural movement, primarily in England between 1710 and 1760, set up in reaction to the Baroque style of architecture; marked by the rediscovery of works of Inigo Jones and the earlier works of Andrea Palladio. Occasionally called Burlingtonian style or Palladian Revival.

Anglo-Saxon architecture The pre-Romanesque architecture of England before the Norman Conquest (1066 A.D.), which survived for a short time thereafter; characterized by massive walls and round arches; a belt course or pilaster strips; triangular arches; long-and-short work.

angstrom A unit of length; used to express electromagnetic wavelengths; 1 Å = 10^-10 meter =

nanometer. Abbr. Å.

angular aggregate Aggregate, the particles of which possess well-defined edges formed at the intersection of roughly planar faces.

angular capital Same as angle capital.

angular frequency (ω) The frequency of a periodic quantity multiplied by 2π; expressed in radians.

angular hip tile Same as angle tile.

angular pediment A pediment having a horizontal cornice and slanting sides that meet in a point at the top so as to form a triangle; also called a triangular pediment.

anhydrite A natural mineral calcium sulfate, used in the manufacture of portland cement to control its set.

anhydrous calcium sulfate, dead-burnt gypsum Gypsum from which all the water of crystallization has been removed.

anhydrous gypsum plaster Plaster which has a greater percentage of the water of crystallization removed than normal gypsum plasters; used as a finish plaster. Requires the addition of an accelerator to produce a set.

anhydrous lime See lime.

animal black A black pigment made by charring of animal bones; sometimes used in paints, although carbon black generally is preferred for tinting strength and blackness. Available in three grades: boneblack, drop black, and ivory black.

animal glue, hide glue A glue made from the bones, hide, horns, and connective tissues of animals; when used hot, it develops strong bonds; has poor water resistance.

anisotropic Descriptive of a material (such as wood) that does not have the same physical properties in all directions.

ANL On drawings, abbr. for “anneal.”

annealed glass Glass created by a process that moves it, in a molten form, along a long oven where it is heated and then slowly cooled under controlled conditions, emerging as a flat, “fire polished” glass product.

annealed tube See soft copper tube.

annealing A process of holding a material at an elevated temperature, but below its melting point, to permit the relieving of internal stresses in the material.

annex, annexe A subsidiary structure near or adjoining a larger principal building.

annexation The acquisition of new territory by a governmental authority, such as a city or state.

annual plant A plant whose life cycle is completed in a single growing season.

annual ring, growth ring A layer of wood produced during one year of a tree’s growth.

annular Said of a ring-shaped structure or object.

annular crypt A crypt in a church that has a semi-circular ambulatory leading to the main chamber, which contains a relic of a saint.

annular molding Any molding that is circular in plan, such as the torus at the base of a column.

annular nail A nail with circular ridges around its shaft; provides greater holding power than a nail without such ridges.

annular vault A barrel vault in the shape of a ring, instead of a straight line; covers a space of which the plan is formed by the area between two concentric circles, or any portion of such a space.

annulated column A shaft or cluster of shafts fitted, at intervals, with rings.

annulet A small molding, usually circular in plan and square or angular in section; esp. one of the fillets encircling the lower part of the Doric capital above the necking.

annunciator 1. A signaling device, usually electrically operated, that emits an audible signal and/or a visual indication under selected circumstances; for example, it may sound an alarm in the case of fire or unauthorized entry. 2. See car annunciator.

ANOD On drawings, abbr. for anodize.

anode In an electric system to protect underground iron pipes or structures from electrochemical action, a metallic rod which is driven in the ground; direct current is passed through the rod to the earth, and then through the iron pipe or structure, in a direction opposite to that resulting from the electrochemical properties of the soil.

anodic coating The surface finish resulting from anodizing; may be transparent or colored by the use of a dye or pigment in the anodizing process.

anodize To provide a hard, noncorrosive, electrolytic, oxide film on the surface of a metal, particularly aluminum, by electrolytic action.

anse de panier Same as basket-handled arch.

ANSI Abbr. for American National Standards Institute.

anta (pl. antae) A pilaster or a rectangular pier formed by a thickening at the end of a wall, usually projecting into a façade or portico; its capital and base usually differ from those on columns within the portico. Antae usually occur in pairs, with one on each side of the portico. If there are columns within the portico that are between the antae, they are said to be in antis. Also see distyle in antis.

anta cap The capital of an anta.

antebellum Dating before or existing before the US Civil War (1861–1865).

antecabinet A room, often spacious and elegant, leading to a private audience room or cabinet.

antechamber 1. A room preceding a chamber. 2. A foyer, lobby, or vestibule.

antechapel A separate entrance space, as a porch or vestibule, in front of a chapel.

antechoir The space, more or less enclosed, between the inner and outer gates of the choir screen.

antechurch A deep narthex at the front of a church, usually with a nave and side aisles.

antecourt An entrance court or outer court which precedes the principal court, as at Versailles; a forecourt.

antefix 1. A decorated upright slab used in classical architecture and derivatives to close or conceal the open end of a row of tiles which cover the joints of roof tiles. 2. A similar ornament on the ridge of a roof.

antemural The outerworks or wall surrounding and protecting a castle.

antenave A narthex or porch of any description leading into the nave of a church.

antepagment 1. A stone or stucco which serves as a decorative dressing that enriches the jambs and head of a doorway or window; an architrave, 2. 2. A jamb or molded architrave of a door.

antependium A wooden hanging which was once displayed over, and in front of, the altar of a medieval church.

antepodium A seat behind the dais in a choir, reserved for the clergy.

anteport A preliminary portal; an outer gate or door.

anteportico An outer porch or a portico in front of the main portico in a classical temple.

anterides In ancient Greek and Roman architecture, a structure to strengthen another; a type of buttress placed against an outer wall, esp. in subterranean construction.

anteroom A room adjacent to a larger, more important one; frequently used as a waiting area.

ante-temple The narthex of an ancient temple.

anthemion, honeysuckle ornament A common Greek ornament based upon the honeysuckle or palmette. Used singly on stelae or antefixes, or as a running ornament on friezes, etc.

antic, antic work A grotesque sculpture consisting of animal, human, and foliage forms incongruously run together and used to decorate molding terminations and many other parts of medieval architecture. Sometimes synonymous with grotesque or arabesque.

anticorrosive paint A paint formulated with a corrosive-resistant pigment (such as lead chromate, zinc chromate, or red lead) and a chemical and moisture-resistant binder; used to protect iron and steel surfaces.

anticum The front of a classical building, as distinguished from the posticum; same as pronaos.

antidesiccant Material applied to plants prior to transplanting to reduce the amount of moisture lost from transpiration.

antiflooding interceptor Same as backwater valve.

antifreeze sprinkler system A wet-pipe sprinkler system whose piping is filled with an antifreeze solution. When the system is activated, the antifreeze solution is discharged, followed by a discharge of water from the water supply to which it is connected.

antifriction bearing Any bearing having the capability of reducing friction effectively.

antifriction latch bolt In builders’ hardware, a latch bolt designed to reduce friction as the bolt engages the strike plate.

antimonial lead, hard lead, regulus metal An alloy containing 10 to 25% antimony and the balance lead; antimony increases the tensile strength and hardens the lead; used in roofing, tank lining, and cladding, 2.

antimony oxide A white opaque pigment used in paints and plastics to provide flame-retardant properties. It has better opacity than extenders but is not as good as titanium dioxide.

antimony yellow See Naples yellow.

antiparabema One of two chapels at the entrance end of a Byzantine church.

antipumping A feature that prevents the reclosing of a circuit breaker until the cause of the closing has been corrected.

antique crown, eastern crown A heraldic device consisting of a headband with an indefinite number of pointed rays projecting from it.

antique glass A textured cylinder glass of uneven thickness, used primarily in stained glass windows; similar in characteristics to the stained glass of the Middle Ages.

antiquing A technique of handling wet paint, by combing, graining, or marbling, so as to expose parts of the undercoat; also called broken-color work.

antiquum opus Same as opus incertum.

antis, in See in antis.

anti-sing lamp Same as low-noise lamp.

anti-siphon An adjective applied to a mechanical device, such as a valve, that eliminates siphonage.

anti-siphon trap See deep-seal trap.

anti-siphonage vent Same as back vent.

anti-siphon vacuum breaker A device (or means) for preventing back siphonage.

antislip paint A paint with a high coefficient of friction, caused by addition of sand, wood flour, or cork dust; used on steps, porches, and walkways to prevent slipping.

antismudge ring A frame attached around the perimeter of a ceiling-mounted air diffuser, which minimizes the formation of rings of dirt on the ceiling.

antistatic agent An agent which minimizes static electricity in plastics; may consist of chemical additives or metallic devices connected to an electrical ground.

anti-sun glass See coated glass and tinted glass.

AP Abbr. for “access panel.”

APA Abbr. for “American Plywood Association.”

apadana The columnar audience hall in a Persian palace.

apartment 1. A room or suite of rooms designed to be lived in, containing at least one bathroom; is separated from, and is usually one of, many similar units within a multiple dwelling. 2. A building containing at least three such dwelling units; an apartment house. Also see efficiency apartment, garden apartment, apartment hotel.

apartment hotel 1. A hotel which rents living quarters suitable for light housekeeping and supplies hotel services. 2. An apartment house which supplies living quarters suitable for light housekeeping and has public dining facilities.

apartment house See apartment, 2.

apartments (Brit.) A group of rooms used as a dwelling by one person or one family.

APC On drawings, abbr. for “acoustical plaster ceiling.”

apex In architecture or construction, the highest point, peak, or tip of any structure.

apex stone, saddle stone The uppermost stone in a gable, pediment, vault, or dome; usually triangular, often highly decorated.

apodyterium A room in Greek or Roman baths, or in the palaestra, where the bathers or those taking part in gymnastic exercises, undressed and dressed.

aponsa A shed roof having rafters that are let into, or rest upon, a wall.

apophyge 1. That part of a column where the shaft of the column springs from its base or where the shaft terminates at its capital; usually molded in a concave sweep; also called a scape or congé. 2. The hollow (i.e., scotia) beneath the echinus of some Classical capitals.

aposthesis Same as apophyge.

apostilb A unit of luminance equal to (1/π) candela per square meter.

apotheca In ancient Greece and Rome, a storeroom of any kind, but esp. one for storing wine.

appareille The slope or ascent to the platform of a bastion.

apparent brightness See brightness.

apparent candlepower Of an extended light source at a specified distance: the candlepower of a point source which produces the same illumination at that distance.

apparent density 1. The mass per unit volume of in-place thermal insulation. 2. The mass per unit volume (or the weight per unit volume) of a material, including the voids which are inherent in the material.

APPD On drawings, abbr. for approved.

appentice, pent, pentice A minor structure built against the side of a building, with a roof of single slope; a penthouse, 3.

appliance, appliance equipment Any device (other than industrial) which utilizes gas or electricity as a fuel to produce air-conditioning, heat, light, refrigeration, or to perform one or more functions such as dishwashing; usually built in a standard size or type and installed or connected as a unit.

appliance lamp An electric lamp designed for high-temperature service.

appliance outlet See outlet.

appliance panel In electric systems, a metal housing containing two or more devices (such as fuses) for protection against excessive current in circuits which supply portable electric appliances with current.

appliance regulator A regulator for controlling and maintaining a uniform pressure of gas supplied to an appliance.

application for payment The contractor’s written request for payment of amount due for completed portions of the work, 1 and, if the contract so provides, for materials delivered and suitably stored pending their incorporation into the work.

application life Same as working life.

applied molding A molding that is nailed on, laid on, or otherwise fastened to a surface, rather than cut into the surface itself.

applied ornament Same as appliqué, 2.

applied trim Supplementary and separate decorative strips of wood or moldings applied to the face or sides of a frame, as on a doorframe.

appliqué 1. An accessory decorative feature applied to an object or structure. 2. In ornamental work, one material affixed to another.

appraisal An evaluation or estimate (preferably by a qualified professional appraiser) of the market or other value, cost, utility, or other attribute of land or other facility.

approach-zone district In zoning, a classification which identifies all that area outward from the end of, or approach to, a runway in which the height of structures or other hazards to aircraft is restricted.

approval drawing In building construction, one of the drawings furnished by a manufacturer to a purchaser for his approval. Such an approval affirms that the manufacturer has correctly interpreted all contractual requirements.

approved 1. Referring to materials, devices, or construction accepted by the authority having jurisdiction, by reason of tests or investigations conducted by it or by an agency satisfactory to the authority, or by reason of accepted principles or tests by national authorities or technical or scientific organizations. 2. Referring to occupancy or use, accepted by the authority having jurisdiction by reason of the submission of adequate proof of conformity with the basic requirements of the code under which the authority functions.

approved equal Material, equipment, or method approved by the architect for use in the work, 1 as being acceptable as an equivalent in essential attributes to the material, equipment, or method specified in the contract documents.

approved ground A ground (such as the steel framework of a building, a concrete-encased electrode, or a ground ring) that meets the requirements of the National Electrical Code or other applicable code.

approving authority The individual agency, board, department, or official established and authorized by a political subdivision (e.g., state, province, county, city, or parish) which is created by law to administer and enforce specified requirements.

APPROX On drawings, abbr. for “approximate.”

appurtenance 1. Any built-in, nonstructural portion of a building, such as doors, windows, ventilators, electrical equipment, partitions, etc. 2. An incidental property right, as a right-of-way.

appurtenant structure A structure attached to the exterior of a building or erected on the roof, usually designed to support service equipment or to support a billboard or the like.

APPX On drawings, abbr. for “appendix.”

apron 1. A flat broad piece of finished lumber or trim placed directly under a windowsill. 2. A flat piece of wood mounted under the base of a cabinet. 3. Same as counterflashing. 4. Same as apron flashing. 5. Paneling on the exterior of a building which serves as a protection against weather or as a decorative feature. 6. That portion of a concrete slab which extends beyond the face of a building on adjacent ground, as the extension of a garage floor. 7. A vertical panel at the back of a sink or lavatory. 8. In a theater, that part of a stage which projects into the audience area beyond the proscenium and curtain line; a forestage.

apron flashing 1. The flashing that covers the joint between a vertical surface and a sloping roof, as at the lower edge of a chimney. 2. The flashing that diverts water from a vertical surface into a gutter.

apron lift A hydraulic or mechanical lift which extends the fixed apron of a stage in front of a proscenium opening.

apron lining The piece of boarding which covers the rough apron piece of a staircase.

apron molding See apron, 2.

apron piece, pitching piece A horizontal wood beam, fixed into a wall and projecting horizontally, which supports the ends of carriage pieces, roughstrings, and joists at the landings of a wooden staircase.

apron rail A lock rail having a raised ornamental molding.

apron sink A deep-sided sink whose front and sides are extended downward from the upper edge, forming an apron around the sink.

apron stage In a proscenium theater, an extension of the fixed apron (in front of a proscenium opening) by means of a platform or by an apron lift.

apron wall In an exterior wall, a panel which extends downward from a windowsill to the top of a window below.

apse A semicircular (or nearly semicircular) or semipolygonal space, usually in a church, terminating an axis and intended to house an altar.

apse aisle An aisle or ambulatory extending around an apse or chevet.

apse chapel A chapel opening from an apse; such a radial chapel is a conspicuous feature of French Gothic architecture.

apsidal Pertaining to an apse or similar to one.

apsidiole A small apsidal chapel, esp. one projecting from an apse. There are often several chapels projecting from the apse.

apsis The semicircular termination of any rectangular chamber; an apse.

APT 1. On drawings; abbr. for apartment. 2. Abbr. for Association for Preservation Technology.

apteral Descriptive of a classical temple or similar building that has no columns along the sides but may have a portico at one or both ends.

APW On drawings, abbr. for “architectural projected window.”

aqueduct A channel for supplying water; often underground, but treated architecturally on high arches when crossing valleys or low ground.

aquifer A water-bearing formation of gravel, permeable rock, or sand that is capable of providing water, in usable quantities, to springs or wells.

aquila A tympanum decorated with carvings.

AR 1. On drawings, abbr. for “as required.” 2. On drawings, abbr. for “as rolled.”

ara Any Classical structure elevated above the general ground level which is used to make offerings to the gods.

arabesque 1. Intricate overall pattern of geometric forms or stylized plants used in Muslim countries. 2. Overall decorative pattern of acanthus scrolls, swags, candelabrum shafts, animal or human forms, on panels or pilasters, in Roman and Renaissance architecture. 3. A species of ornament of infinite variety used for enriching flat surfaces or moldings, either painted, inlaid, or carved in low relief.

Arabic arch A horseshoe arch.

araeostyle Same as areostyle; see intercolumniation.

araeosystyle, areosystyle Alternately systyle and araeostyle; having an intercolumniation alternately of two and four diameters.

arbitration The binding resolution of disputes by one or more neutral persons (usually called “arbitrators”), as a substitute for judicial proceedings; may be invoked only by agreement of the parties to the dispute, but such agreement may be arrived at before there is an actual dispute, as, for example, through a clause in a contract between them, or after a dispute has arisen. Arbitration proceedings characteristically are less formal than those in court, and the rules of evidence and most rules of substantive law that would be invoked by a court are not applied.

arbor 1. A light, open structure having a lattice framework, usually supporting intertwined vines or flowers; a shaded, leafy recess, often formed by tree branches. 2. See counterweight arbor. 3. The rotating shaft of a circular saw, spindle molder, shaper, etc.

arboretum An informally arranged garden, usually on a large scale, where trees are grown for display, educational, or scientific purposes.

arc 1. The luminous column of gas in an arc discharge; caused by the flow of electric current between separated electrodes in a gas. 2. See carbon-arc spotlight. 3. Any part of the circumference of a circle. 4. An angular measure.

arca custodiae In ancient Roman architecture, a type of cell for the confinement of prisoners.

arcade 1. A line of counterthrusting arches raised on columns or piers. Also see blind arcade, coupled arcade, interlacing arcade, intersecting arcade, surface arcade, wall arcade. 2. A covered walk with a line of such arches along one or both long sides. 3. A covered walk with shops and offices along one side, and a line of such arches on the other. Also see stoa. 4. A covered walk, lit from the top, lined with shops or offices on one or more levels.

arcading A line of arches, raised on columns, that are represented in relief as decoration of a solid wall; sometimes seats are incorporated in the composition.

arcae In ancient Roman architecture, the gutters of the cavaedium.

arcature 1. Arcading. 2. An ornamental, miniature arcade.

arc-boutant Same as flying buttress.

arc cutting A process of cutting or removing metal by melting it with the heat produced between an electrode and the metal being cut.

arc de cloître A groined vault having reentrant angles.

arc de triomphe Same as triumphal arch.

arc discharge An electric discharge characterized by the production of light, high cathode-current densities, and a low voltage drop at the cathode.

arc doubleau An arch, usually very massive, carried across a wide space, to support a groined vault or to stiffen a barrel vault.

arcella A cheese room, in medieval architecture.

arc formeret The wall arch or wall rib, or the corresponding rib coming next to the arcade between nave and aisle, or the like, as in Gothic vaulting.

arc gouging A groove or bevel formed in metal as a result of arc cutting.

arch A construction that spans an opening; usually curved; often consists of wedge-shaped blocks (voussoirs) having their narrower ends toward the opening. Arches vary in shape, from those that have little or no curvature to those that are acutely pointed. For special types of arches, see acute arch, anse de panier, arrière-voussure, back arch, basket-handle arch, bell arch, blind arch, camber arch, catenary arch, cinquefoil arch, compound arch, cusped arch, diminished arch, discharging arch, Dutch arch, elliptical arch, equilateral arch, flat arch, Florentine arch, foil arch, French arch, garden arch, gauged arch, Gothic arch, horseshoe arch, inverted arch, jack arch, keel arch, keystone arch, lancet arch, Mayan arch, memorial arch, miter arch, Moorish arch, ogee arch, pointed arch, Queen Anne arch, raking arch, rampant arch, rear arch, relieving arch, round arch, rowlock arch, safety arch, sconcheon arch, secondary arch, segmental arch, semicircular arch, semielliptical arch, shouldered arch, skew arch, straight arch, three-centered arch, transverse arch, trefoil arch, triangular arch, triumphal arch, Tudor arch, two-centered arch.

ARCH. On drawings, abbr. for architect, architecture, or architectural.

archarium Same as archivium.

arch band Any narrow elongated surface forming part of, or connected with, an arch.

arch bar A curved wrought-iron or steel bar used to support the weight of the masonry above a fireplace or window opening.

arch barrel roof See barrel vault.

arch beam Same as arched beam.

arch brace A curved brace, usually used in pairs to support a roof frame and give the effect of an arch.

arch brick, compass brick, featheredge brick, radial brick, radiating brick, radius brick, voussoir brick 1. A wedge-shaped brick used in arch or circular construction; its two larger faces are inclined toward each other. 2. Extremely hard-burnt brick from an arch.

arch buttant Same as flying buttress.

arch buttress Same as flying buttress.

arch center Formwork to support the voussoirs of an arch during construction.

arch corner bead A corner bead that is cut on the job; used to form and reinforce the curved portion of an arch opening.

arched barrel roof Same as barrel roof.

arched beam A beam whose upper surface is slightly curved.

arched butment Same as flying buttress.

arched buttress Same as flying buttress.

arched construction A method of construction relying on arches and vaults to support walls and floors.

arched corbel table In early Christian and Romanesque architecture and their derivatives, a corbel table (often near the top of a wall) composed of small blind arches that are regularly punctuated by pilaster strips.

arched dormer A dormer having an approximately semicylindrical roof; the head of the upper sash in the dormer may be either round-topped or flat-topped.

arched tomb A tomb chest that lies within an arched niche in a wall.

archeion See archivium.

archeria In medieval fortifications, an aperture through which an archer or longbowman might discharge arrows.

archiepiscopal cross A cross with two transverse arms, the longer one nearer the center.

arching 1. The transfer of stress from a yielding part of a soil mass to adjoining less-yielding or restrained parts of the mass. 2. A system of arches. 3. The arched part of a structure.

architect 1. A person trained and experienced in the design of buildings and the coordination and supervision of all aspects of the construction of buildings. 2. A designation reserved, usually by law, for a person or organization professionally qualified and duly licensed to perform architectural services, including analysis of project requirements, creation and development of the project design, preparation of drawings, specifications, and bidding requirements, and general administration of the construction contract. An architect usually renders services that require the application of art, science, and the aesthetics of design to the construction of buildings, including their components and appurtenances and the spaces around them, taking into account the safeguarding of life, health, property, and public welfare; often includes consultation, evaluation, planning, the provision of preliminary studies, designs, and construction documents; and may also include construction management, and the administration of construction documents.

architect-engineer An individual or firm offering professional services as both architect and engineer; term generally used in government contracts, particularly those with the federal government.

architect-in-training Same as intern architect.

architectonic Related or conforming to technical architectural principles.

architect’s approval The architect’s written or imprinted acknowledgment that materials, equipment, or methods of construction are acceptable for use in the work, 1, or that a contractor’s request or claim is valid.

architect’s scale A scale having graduations along its edges so that scale drawings can be measured directly in feet (or meters); often triangular in shape.

architectural 1. Pertaining to architecture, its features, characteristics, or details. 2. Pertaining to materials (such as stone, mosaic, or bronze) used to build or ornament a structure.

architectural area Total floor area of a building calculated from its exterior surfaces or from the center line of a common wall between two buildings; usually excludes open terraces. Roofed areas such as porches or arcades are calculated at one-half actual area.

architectural barrier An architectural feature that creates inaccessibility or prevents the free movement of disabled people within a building.

Architectural Barriers Act An Act passed by the US Congress in 1968 requiring that buildings financed with federal funds, and/or owned or leased by the federal government, be constructed or modified so that they are accessible to, and can be used by, physically disabled people.

architectural bronze An alloy containing 57% copper, 40% zinc, 2.75% lead, 0.25% tin; used for extruded moldings and forgings. Not technically a bronze.

architectural coating A coating which is usually intended for on-site application of interior and/or exterior surfaces of buildings.

architectural concrete 1. Reinforced concrete used for structural and ornamental work. 2. In nonconcrete frame structures, the exposed concrete used for aesthetic effects.

architectural details The relatively small elements of design and finish of a building.

architectural drawing One of a number of drawings prepared by an architect for a construction project, e.g., plans, elevations, and details.

architectural fountain A system of pumps, tubes, pipes, controls, valves, and nozzles through which water is forced under pressure to produce ornamental jets, spouts, or showers; often lighted for special nighttime effects.

architectural glass Any of several types of configurated glass.

architectural hardware All hardware used in building construction, especially that which is attached to movable elements such as doors and windows; also called finish hardware.

architectural ironmongery (Brit.) Same as architectural hardware.

architectural millwork, custom millwork Ready-made millwork as obtained from the mill, especially fabricated to meet the specifications for a particular job, as distinguished from standard or stock items or sizes.

architectural mode An inexact classification for buildings that share selected architectural features but, unlike an architectural style, may not share consistency of design, form, or ornamentation with other buildings similarly classified. When such buildings seemingly emulate an earlier prototype (for example, American Colonial Revival), important architectural details that characterize the prototype are often either omitted or exaggerated in size or importance; furthermore, other design elements may be added (such as a type of dormer, chimney, or window) that never existed in the prototype; or characteristic building materials of the prototype may be replaced with newer types of materials. Compare with architectural style.

architectural projected window A window in which the basic frame and hinged sash (ventilator, 2) members are made of heavier steel than that used in a commercial projected window.

architectural section See section, 2.

architectural sheet metal See sheet metal.

architectural style A classification characterizing buildings that share many common attributes, including similarity in general appearance, in the arrangement of major design elements in ornamentation, in the use of materials, and in form, scale, and structure. Such styles are often related to a particular period of time, geographical region, country of origin, or religious tradition, or to the architecture of an earlier period. Often, a term that includes the word style (such as Santa Fe style) is an architectural mode rather than an architectural style.

architectural terra-cotta A hard-burnt, glazed or unglazed clay unit used in building construction; plain or ornamental; machine-extruded or hand-molded; usually larger in size than brick or facing tile. Also see ceramic veneer.

architectural volume The cubic content of a building calculated by multiplying the floor area by the height. For foundations, the average depth of footing to the finish floor is used. For roofs (other than flat roofs), the average height is used.

architecture 1. The art and science of designing and building structures, communities, or open areas, in keeping with aesthetic and functional criteria. 2. Structures built in accordance with such principles.

architrave 1. In the classical orders, the lowest member of the entablature; the beam that spans from column to column, resting directly upon their capitals. Also see order. 2. The ornamental moldings around the faces of the jambs and lintel of a doorway or other opening; an antepagment.

architrave bead A metal stop bead which is fixed to a wall next to a door or window opening; covered by the architrave.

architrave block Same as skirting block.

architrave cornice An entablature in which the cornice rests directly on the architrave, the frieze being omitted.

archivium In ancient Greece and Rome, a building in which archives of a city or state were deposited; also called archeion or tabularium.

archivolt An architrave modified by being carried around a curved opening instead of a rectangular one; an ornamental molding or band of moldings on the face of an arch following the contour of the extrados.

archivoltum A medieval conduit or receptacle for waste materials, as a sewer or cesspool.

arch order 1. In Roman architecture, arches enframed by engaged columns and entablatures. 2. In medieval architecture, successive vertical planes of arches and colonettes set one within another.

arch rib 1. In Romanesque architecture, a transverse rib crossing the nave or aisle at right angles to its length. 2. A principal load-bearing member of a ribbed arch.

arch ring In an arched structure, the curved member that sustains the principal load.

arch stone Same as voussoir.

arch surround A seldom-used term for a decorative border around an arch; same as archivolt.

arch truss A truss having an arched upper chord (concave downward) and a straight bottom chord; there are vertical hangers between the two chords.

archway A passage through or under an arch, especially when long, as under a barrel vault.

arc light A high-intensity light source produced by an arc, usually, between two metal electrodes or between two carbon rods; also see carbon-arc spotlight.

arcosolium An arched recess or sepulchral cell in a Roman subterranean burial place or catacomb.

arcs doubleaux Same as arch band.

arc spotlight See carbon-arc spotlight.

arcuated Based on, or characterized by, arches or archlike curves or vaults. It is common to distinguish between trabeated (beamed) and arcuated buildings.

arcuated lintel A Syrian arch.

arcuatio In ancient Rome, a structure formed by means of arches or arcades and employed to support a construction of any kind, such as an aqueduct.

arcus ecclesiae In medieval architecture, the arch by which the nave of the church was divided from the choir or chancel.

arcus presbyterii In medieval architecture, the arch over the tribune, 2.

arcus toralis The lattice separating the choir from the nave in a basilica.

arcus triumphalis A triumphal arch.

ARC W, ARC/W On drawings, abbr. for arc weld.

arc weld A weld in which the heat of fusion is supplied by an electric arc.

arc welding The joining of metal parts by fusion, in which the necessary heat is produced by means of an electric arc, sometimes accompanied by the use of a filler metal and/or the application of pressure.

are An area equal to 100 sq m.

area 1. Measurement of surface within specified boundaries. 2. Space either within or outside a structure or location, designated for a specific purpose, as recreation and/or parking area. 3. An uninterrupted interior space. 4. An areaway. 5. The cross-sectional area of steel reinforcement.

area divider A raised edge on a roof membrane that divides it into smaller areas.

area drain A receptable designed to collect surface or rainwater from an open area.

area efficiency Of a building, the ratio of the net usable floor area (or the net rentable area) to the gross floor area.

area grouting The grouting of an area in which (closely spaced) shallow holes have been drilled in a pattern in bedrock. This grouting has the effect of strengthening the upper portions of the bedrock and making it less pervious.

area light 1. A source of light with significant dimensions in two directions, such as a window or luminous ceiling. 2. A light used to illuminate large areas.

area method A method of estimating probable total construction cost by multiplying the adjusted gross floor area by a predetermined cost per unit of area.

area of refuge An area where individuals who are in a building may gather safely in case of fire and/or smoke; usually an outdoor area adjacent to the building, or an area protected by fire-rated walls.

area of rescue assistance Same as area of refuge.

area of steel See area, 5.

area separation wall A fire-rated partition designed to prevent the spread of fire from an adjoining occupancy.

area wall A retaining wall around an areaway.

areaway An open subsurface space adjacent to a building used to admit light and air or as a means of access to a basement or crawl space.

arena 1. An acting space of any shape surrounded by seats. 2. A type of theater not having a proscenium, the spectators’ seats, rising in tiers, wholly surrounding the stage. 3. The sanded central area in a Roman amphitheater or circus, surrounded by the seats. 4. Any building, indoor or outdoor, for sports events, etc.

arenaceous Composed primarily of sand; sandy.

arena theater See arena, 2.

arena vomitory A vomitory through a section of seats which provides a special access, for actors, to an arena stage.

areostyle, araeostyle See intercolumniation, 2.

argillaceous Composed primarily of clay or shale; clayey.

argillite A rock containing chiefly clay materials; derived from claystone, siltstone, or shale; used locally as building stone, although rarely produced commercially.

ARI Abbr. for “Air-Conditioning and Refrigeration Institute.”

aris See arris.

ark An ornamental, enclosed repository in a synagogue for the scrolls of the Torah.

arkose Sandstone containing 25% or more feldspar grains in abundance; used as building stone.

armarium Same as ambry.

armature 1. The heavy-current winding of a motor or generator. 2. The winding in a solenoid or relay. 3. Structural ironwork in the form of framing or bars (commonly employed in medieval buildings) used to reinforce slender columns, or to consolidate canopies or hanging members such as bosses, and in tracery.

arm conveyor A conveyor for building materials in the form of an endless belt or chain, to which are attached projecting arms or shelves which carry the materials.

armored cable, metal-clad cable Two or more individually insulated electric conductors having a common outer protective covering of metal. Also see BX.

armored clamp A fitting which grips the armor of a cable where the armor terminates or where the cable enters a junction box.

armored faceplate A tamperproof faceplate or lock front, mortised in the edge of a door to cover the lock mechanism.

armored front In builders’ hardware, a lock front which consists of two plates: the under plate (an unfinished plate fastened to the case) and the finish plate (a plate which covers the cylinder setscrews, thus protecting them from tampering, and which is fastened to the under plate); used on mortise locks.

armored-plate door A door fabricated of tempered glass.

armored plywood Plywood which is faced on one or both sides with metal sheeting.

armored wood Metal-clad wood.

armor plate A metal plate which protects the lower part of a door from kicks and scratches; similar to a kickplate but covering the door to a greater height, usually 39 in. (1 m) or more from the bottom of the door.

armor-plate glass See bullet-resisting glass, tempered glass.

armory 1. A building used for military training or storage of military equipment. 2. A weapons-manufacturing plant.

aromatic cedar See eastern red cedar.

arrectarium In Classical Roman construction, an upright pillar or post which is load-bearing.

arrester 1. At the top of an incinerator or chimney, a wire screen which prevents sparks or burning material from leaving the stack. 2. See lightning arrester. 3. See surge arrester. 4. See water-hammer arrester. 5. A lightning arrester. 6. A grease trap.

arrière-voussure, rear arch 1. A rear vault; an arch or vault in a thick wall carrying the thickness of the wall, esp. one over a door or window frame. 2. A relieving arch behind the face of a wall.

arris, aris 1. An external angular intersection between two planar faces (an edge), or two curved faces, as in moldings or between two flutes on a Doric column or between a flute and the fillet on an Ionic or a Corinthian column. 2. The sharp edge of a brick.

arris fillet A triangular batten used to tilt up the lowest course of slates on a roof, at the edge of gutters.

arris gutter A V-shaped wooden gutter fixed to the eaves of a building.

arris hip tile, angle hip tile A special roof tile having an L-shaped cross section, made to fit over the hip of a roof.

arris rail A rail of triangular section, usually formed by slitting diagonally a strip of square section; the broadest surface forms the base.

arrissing tool A tool similar to a float, but having a form suitable for rounding an edge of freshly placed concrete.

arris tile Any angularly shaped tile.

arris-trenched A housing, 1 that is cut obliquely through an arris.

arrisways, arriswise Diagonally, in respect to the manner of laying tiles, slates, bricks, or timber.

arrow diagram In CPM, an arrangement of arrows, representing activities, that describe a project.

arrow loop, loophole A vertical slit for archers in medieval fortification walls, with jambs deeply splayed toward the interior.

arrow slit Same as arrow loop.

ARS On drawings, abbr. for asbestos roof shingles.

ART. On drawings, abbr. for “artificial.”

Art Deco A decorative style stimulated by the Paris Exposition International des Arts Decoratifs et Industrielles Modernes of 1925, widely used in the architecture of the 1930s, including skyscraper designs such as the Chrysler Building in New York; characterized by sharp angular or zigzag surface forms and ornaments. Also referred to as Style Moderne.

artemiseion A building or shrine dedicated to the worship of Artemis.

arterial street A street that provides a direct route for long-distance travel within different parts of a city.

arterial vent A vent serving a building drain and a public sewer.

artesonado In Hispanic architecture, a ceiling, usually having a paneled appearance, comprised of sections and/or interlacing strips.

art glass A type of colored glass used in windows during the late 19th and early 20th centuries; characterized by unusual combinations of hues and special effects in transparency and opaqueness.

article 1. A subdivision of a document. 2. In project specifications, the primary subdivision of the section, often further subdivided into paragraphs, subparagraphs, and clauses.

articulated drop chute A drop chute, for a falling stream of concrete, which consists of a vertical succession of tapered metal cylinders, so designed that the lower end of each cylinder fits into the upper end of the one below.

articulated structure A structure which permits relative motion to occur between its parts (e.g., by means of one or more sliding or hinged joints).

artifact See building artifact.

artificial Made to resemble a natural material or object, for example, faux marbre.

artificial daylight Light provided by an artificial source which has a spectral distribution approximating that of natural daylight at a correlated color temperature.

artificial horizon A device for indicating the horizon, as a bubble, pendulum or the flat surface of a liquid.

artificially dried See kiln-dried.

artificial marble See artificial stone.

artificial monument A relatively permanent object used to identify the location of a survey station or corner.

artificial sky A dome (usually hemispherical) illuminated by concealed light sources; used to illustrate and study daylighting techniques on architectural models placed near the center of the hemisphere.

artificial stone A mixture of stone chips or fragments, usually embedded in a matrix of mortar, cement, or plaster; the surface may be ground, polished, molded, or otherwise treated to simulate stone; variously called art marble, artificial marble, cast stone, marezzo, patent stone, and reconstructed stone.

art marble See artificial stone.

Art Moderne An architectural style found principally in houses constructed in the 1930s, following the earlier Art Deco style. Common characteristics may include smooth stuccoed wall surfaces; flat roofs; architectural details that emphasize the horizontal appearance of the building; rounded exterior corners; ribbon windows that may continue around a corner; glass blocks; an asymmetrical façade. The jagged version of this style is sometimes called Zigzag Moderne. Also see International style. Compare with Art Deco and Streamline Moderne.

Art Nouveau A style of decoration in architecture and applied art developed principally in France and Belgium toward the end of the 19th cent.; characterized by organic and dynamic forms, curving design, and whiplash lines. The German version is called Jugendstil, the Austrian variant Sezession; in Italy one speaks of Stile Liberty, in Spain of Modernismo.

Arts and Crafts Movement A group of architects and artisans who emphasized the importance of craftsmanship and high standards in all architectural details; greatly influenced by the outstanding work of William Morris and his company of craftsmen near London. Beginning in the late 19th century and extending into the early 20th century, this movement had a significant impact in America on the Prairie style with its low-pitched roofs and widely overhanging eaves, and on the Craftsman style. In particular, excellent craftsmanship and superior detailing was embraced in the designs of the architects Charles Sumner Greene (1868–1957) and his brother Henry Mather Greene (1870–1954) of Pasadena, California, whose work exemplified architectural details carried to a high art.

art window A term sometimes applied to a window having its upper and lower sashes of different sizes, with the upper sash containing a number of small panes of colored glass.

arx The fortress or citadel of an ancient town.

AS Abbr. for automatic sprinkler.

ASA Abbr. for “American Standards Association;” see American National Standards Institute.

asarotum A type of painted pavement used by the ancient Romans before their use of mosaic work.

asb 1. Abbr. for apostilb. 2. Abbr. for asbestos.

ASBC Abbr. for “American Standard Building Code.”

asbestos, asbestos fiber Fine, flexible, non-combustible, inorganic fiber obtained from natural hydrous magnesium silicate; can withstand high temperatures without change; a poor heat conductor; is fabricated into many forms either alone or with other ingredients. A recognized health hazard.

asbestos abatement, asbestos removal The procedures used in eliminating the release of asbestos fibers or in removing materials containing asbestos (e.g., the process of encapsulation). Also see air monitoring, HEPA filter, and wet cleaning.

asbestos blanket Asbestos fibers (alone or in combination with other fibers) stitched, bonded, or woven into flexible blanket form; used for high-temperature insulation or for fire and flame barriers.

asbestos board See asbestos-cement board.

asbestos-cement board, asbestos-cement wallboard, asbestos sheeting A dense, rigid, board containing a high proportion of asbestos fibers bonded with portland cement; resistant to fire, flame, and weathering; has low resistance to heat flow. Used as a building material in sheet form and corrugated sheeting.

asbestos-cement cladding Asbestos-cement board and component wall systems, directly supported by wall framing, forming a wall or wall facing.

asbestos curtain, fire curtain, safety curtain A curtain which closes the stage of a theater from the auditorium automatically in case of fire, preventing the spread of flame and smoke; usually fabricated of woven asbestos and steel wire, it may be nonrigid, semirigid, or rigid.

asbestos felt A product made by saturating felted asbestos with asphalt or other suitable binder, such as a synthetic elastomer.

asbestos fiber See asbestos.

asbestos joint runner, pouring rope An asbestos rope, wrapped around a pipe and then clamped in position; used to hold molten lead which is poured in a caulked joint.

asbestos plaster A fireproof insulating material generally composed of asbestos with bentonite as the binder.

asbestos roofing Roofing or wall cladding sheets made of asbestos cement; may be plain, corrugated, or variously patterned. Also see asbestos cement board.

asbestos roof shingle A fire-resisting roofing shingle, composed largely of asbestos.

asbestos runner Same as asbestos joint runner.

asbestos structural roofing Heavy asbestos-cement board directly supported by roof framing, forming a roof deck and providing a roof surface for cladding.

as-built drawing A working drawing as modified during construction; includes a record of concealed items (such as conduits for building services), thereby providing information for future reference. Also called record drawings.

ASC Abbr. for “asphalt surface course.”

A-scale In sound-level meters, a weighting network, widely used to measure the noise levels in buildings or communities. The A-scale provides meter readings that correlate better with subjective judgments of noise than do readings of sound pressure levels (which are also taken with a sound level meter, but without a weighting network).

ASCE Abbr. for “American Society of Civil Engineers.”

ascendant See chambranle.

as-constructed See as-built drawing.

ash A hard, strong, straight-grained hardwood of the eastern US having good shock resistance and bending qualities; used as flooring, trim, and decorative veneer.

ash dump An opening in the floor of a fireplace or firebox through which ashes are swept to an ashpit below.

ash house In colonial America, a small dependency for storing ashes that were used primarily for making soap.

ashlar 1. Squared building stone. 2. Ashlar masonry. 3. A vertical stud between the floor beams and rafters of a garret.

ashlar anchor Same as, or functioning as, a cramp.

ashlar brick, rock-faced brick A brick whose face has been hacked to resemble roughly hacked stone.

ashlaring 1. Ashlars, collectively. 2. In garrets, the short wood upright pieces between the floor beams and rafters, to which wall lath is attached.

ashlar line A horizontal line at the exterior face of a masonry wall.

ashlar masonry Masonry composed of rectangular units of burnt clay or shale, or stone, generally larger in size than brick and properly bonded, having sawn, dressed, or squared beds and joints laid in mortar.

ashlar piece A vertical stud between the floor beams and rafters of a garret.

ashlar veneer A veneer wall constructed of ashlar masonry.

ashlering See ashlaring.

ashpan A metal receptacle beneath a grating for collection and removal of ashes.

ashpit A chamber located below the fireplace or firebox for the collection and removal of ashes.

ashpit door A cast-iron door providing access to an ashpit for ash removal.

ASHRAE Abbr. for “American Society of Heating, Refrigerating and Air-Conditioning Engineers.”

ASI Abbr. for “Architects and Surveyors Institute.”

Asiatic base A type of Ionic base; consists of a lower disk with horizontal fluting or scotias (there may be a plinth below the disk) and an upper torus decorated with horizontal fluting on relief; developed in Asia minor.

Asiatic water closet A water closet which has its bowl nearly flush with the floor so that the user adopts a squatting position; widely used in some parts of Asia.

ASID Abbr. for “American Society of Interior Designers.”

asistencia In Spanish Colonial architecture, a chapel usually having no permanent priest but relying on the part-time assistance of visiting padres.

asistencio In Hispanic Colonial architecture, a contributing chapel.

askarel A synthetic electrically insulating liquid which is nonflammable; when decomposed by an electric arc, the gaseous products also are nonflammable.

ASLA Abbr. for American Society of Landscape Architects.

ASME Abbr. for “American Society of Mechanical Engineers.”

aspasticum An apartment or place adjoining the ancient churches or basilicas in which the bishop or presbyters received visits of devotion or in which ceremonies or business was conducted.

aspect The direction which a building faces with respect to the points of a compass.

aspect ratio 1. In any rectangular configuration (such as the cross section of a rectangular duct), the ratio of the longer dimension to the shorter. 2. In a rectangular configuration, the ratio of the long-side to the short-side.

aspersorium A holy-water stoup or font.

asphalt 1. A dark brown to black cementitious material, solid or semisolid, in which the predominating constituents are bitumens which occur in nature. 2. A similar material obtained artificially in refining petroleum; used in built-up roofing systems as a waterproofing agent. 3. A mixture of such substances with an aggregate for use in paving.

asphalt binder course See binder course, 1.

asphalt block A paving block composed of a mixture of 88 to 92% crushed stone and the balance asphaltic cement.

asphalt cement Asphalt that is refined to meet specifications for paving, industrial, and special purposes; see asphaltic cement.

asphalt color coat An asphalt surface treatment with a cover of mineral aggregate which has been selected to produce a desired color.

asphalt concrete See asphaltic concrete.

asphalt cutter A powered machine having a rotating abrasive blade; used to saw through bituminous surfacing material.

asphalt-emulsion slurry seal A mixture of slow-setting emulsified asphalt, fine aggregate, and mineral filler, with water added to produce a slurry consistency.

asphalt felt See breather-type asphalt felt.

asphalt filler See asphalt joint filler.

asphalt fog seal An asphalt surface treatment consisting of a light application of liquid asphalt without a mineral aggregate cover.

asphalt heater A piece of equipment for raising the temperature of bitumen used in paving; usually the bitumen circulates through tubes inside a chamber heated by a burner.

asphaltic base course In asphalt pavement, a foundation layer consisting of mineral aggregate bound together with asphaltic material.

asphaltic cement, asphalt cement A specially prepared asphalt, free of water and material foreign to asphalt; contains less than 1% ash; must be heated to a fluid condition for use; an asphalt specially prepared as to quality and consistency for direct use in the manufacture of bituminous pavements.

asphaltic concrete, asphalt paving, black top A mixture of asphalt and graded aggregate widely used as paving material over a prepared base; normally placed, shaped, and compacted while hot, but can be prepared for placement without heat. Also see cold mix.

asphaltic felt See asphalt prepared roofing. Also see the specific type of felt, as mineral-surfaced felt, sanded flux-pitch felt, etc.

asphaltic macadam A pavement similar to macadam but having asphalt as the binder in place of tar.

asphaltic mastic, mastic asphalt A viscous mixture of asphalt and a filler material such as fine sand or asbestos; hardens when exposed to air; used as an adhesive, as a sealant at joints, and in waterproofing.

asphalting The process of applying asphalt for various construction purposes, as in waterproofing basements and roof decks.

asphalt intermediate course Same as binder course, 1.

asphalt joint filler An asphaltic product used for filling cracks and joints in pavement and other structures.

asphalt lamination A laminate of sheet material, such as paper or felt, which uses asphalt as the adhesive.

asphalt leveling course A course (of an asphalt-aggregate mixture) of variable thickness used to eliminate irregularities in contour of an existing surface, prior to the placement of a superimposed layer.

asphalt macadam See asphaltic macadam.

asphalt mastic See asphaltic mastic.

asphalt overlay One or more courses of asphalt construction on an existing pavement; generally includes an asphalt leveling course to correct the contour of the old pavement.

asphalt paint A liquid asphaltic product sometimes containing small amounts of other materials such as lampblack, aluminum flakes, and mineral pigments.

asphalt panel See premolded asphalt panel.

asphalt paper A paper sheet material that has been coated, saturated, or laminated with asphalt to increase its toughness and its resistance to water.

asphalt pavement A pavement consisting of a surface course of mineral aggregate, coated and cemented together with asphalt cement on supporting courses.

asphalt pavement sealer A compound applied to asphalt pavements to protect the surface from deterioration, from weathering, and from petroleum products.

asphalt pavement structure All of the courses of asphalt-aggregate mixtures placed above the subgrade or improved subgrade.

asphalt paving See asphaltic concrete.

asphalt plank A plank which is fabricated of a mixture of asphalt fiber and mineral filler, often reinforced with steel or fiberglass mesh; sometimes contains mineral grits to provide a sandpaper texture.

asphalt prepared roofing, asphaltic felt, cold-process roofing, prepared roofing, rolled roofing, rolled strip roofing, roofing felt, sanded bituminous felt, saturated felt, self-finished roofing felt A roofing material manufactured by saturating a dry felt with asphalt and then coating the saturated felt with a harder asphalt mixed with a fine mineral, glass-fiber, asbestos, or organic stabilizer; available in the form of rolls. All or part of the weather side may be covered with mineral granules or with powdered talc or mica. The reverse side is covered with a material suitable to prevent sticking in the roll. The granule-surfaced material may be used as cap sheet in built-up roofing.

asphalt prime coat An initial application of an asphalt primer, usually as preparation for a superimposed treatment or construction.

asphalt primer A liquid material of low viscosity which upon application to a nonbituminous surface is completely absorbed; used to waterproof existing surfaces and to prepare them as a base for an asphalt course.

asphalt roofing See asphalt-prepared roofing.

asphalt seal coat A bituminous coating, with or without aggregate, applied to the surface of a pavement to waterproof and preserve the surface and to improve the texture of a previously applied bituminous surface.

asphalt-shingle nail Same as roofing nail.

asphalt shingles, composition shingles, strip slates Shingles manufactured from saturated roofing felts (rag, asbestos, or fiber glass) coated with asphalt and having mineral granules on the side exposed to the weather.

asphalt soil stabilization The treatment of naturally occurring nonplastic or moderately plastic soil with liquid asphalt at normal temperatures to improve the load-bearing qualities of the soil.

asphalt surface course A top course of asphalt pavement.

asphalt surface treatment The application of asphaltic materials to any type of pavement surface or road surface, with or without a cover of mineral aggregate.

asphalt tack coat A light coating of liquid asphalt on an existing asphalt surface or on a portland cement concrete surface; used to ensure a bond between the old surface and the overlaying course.

asphalt tile A resilient, low-cost floor tile composed of asbestos fibers, finely ground limestone fillers, mineral pigments, and asphaltic or resinous binders. Requires waxing and buffing; set in mastic over wood or concrete subfloor; is not greaseproof unless specially treated.

asphaltum 1. Natural asphalt. 2. In painting, asphalt from residues of crude mineral oil.

aspiration In an air-conditioned room, the pulling of room air into the moving air-stream which is discharging from a diffuser.

aspirator A device which draws a stream of liquid or air through it by means of suction which is produced by the flow of a fluid through an orifice.

ASR Abbr. for “automatic sprinkler riser.”

Assam psychrometer A psychrometer, shielded from radiation, in which the air is blown over the bulbs of the two thermometers with a small fan.

ASSE Abbr. for “American Society of Sanitary Engineering.”

assemblage of orders Same as supercolumniation; also see orders.

assembling bolt A threaded bolt for holding together temporarily the several parts of a structure during riveting.

assembly area Same as assembly space.

assembly building A building used for the gathering of persons for the purposes of amusement, deliberation, dining, drinking, education, entertainment, instruction, or awaiting transportation.

assembly occupancy Occupancy of a room, hall, or building by people gathered for a purpose, such as church, restaurant, or bus station.

assembly drawing An engineering drawing of a complete unit, usually including detail drawings of its components.

assembly space A gathering place (such as an auditorium, exclusive of a stage) that is occupied by numbers of persons during major periods of occupancy; some building codes consider every tier of seating in an auditorium to be a separate assembly space.

asser In ancient carpentry: 1. The ribs or brackets of an arched ceiling. 2. The purlins or rafters of a roof. 3. A beam or joist.

assessed valuation The value of a property as determined by a municipality for real estate tax purposes; often this valuation is less than the true market value of the property.

assessment A tax, charge, or levy on property: 1. as a means of computing real estate tax; 2. to pay for specific services or improvements.

assessment ratio Of a property, the ratio between its market value and its assessed value.

assignment 1. The transfer of a legal right. 2. In the case of a lease, the transfer of the right of the tenant to the entire property leased and for the entire term remaining; also see sublease.

assidua That part of a church in which the altar is placed.

assize 1. A cylindrical block of stone forming one unit in a column. 2. A course of stonework.

associate In an architectural firm, a member of an architect’s staff who has a special employment agreement.

associate architect, associated architect An architect who has a temporary partnership, joint venture, or employment agreement with another architect to collaborate in the performance of services for a specific project or series of projects. Also see joint venture.

assommoir A gallery built over a door or passage of a fortified place, from which stones and heavy objects could be hurled down on the enemy.

ASST On drawings, abbr. for “assistant.”

assumption of mortgage The purchaser of property may promise the vendor that he will assume the obligation to keep up the mortgage payments. In such event, the mortgagee may generally enforce this promise against the purchaser, and in addition to his right to foreclose in the event of nonpayment the mortgagee may also recover from the purchaser (or from the vendor) any deficiency between the proceeds of the foreclosure sale and the amount still owing on the mortgage. Also see subject to mortgage.

Assyrian architecture Architecture of the Assyrian empire (centered between the Tigris and Upper and Lower Zab rivers in southwest Asia); was expressive of its might, as conquerors of Mesopotamia and much of the adjacent countries between the 9th and 7th centuries B.C. Mud brick was used as the building material, although stone was available; stone was used only for carved revetments and monumental decorative sculptures. Excavations have uncovered large palaces and temple complexes with their ziggurats as well as extensive fortifications.

astler Old English term for ashlar.

ASTM A non-profit technical society (formerly known as the American Society for Testing and Materials) that develops and publishes standards, definitions of materials, methods for testing materials, recommended installation practices, and specifications for materials.

ASTM portland cement One of eight classifications of portland cement standardized by the ASTM.

astragal 1. A bead, usually half-round, with a fillet on one or both sides. It may be plain, but the term is more correctly used to describe the classical molding consisting of a small convex molding decorated with a string of beads or bead-and-reel shapes. 2. A plain bead molding. Also called roundel, baguette, or chaplet. 3. A member, or combination of members, fixed to one of a pair of doors or casement windows to cover the joint between the meeting stiles and to close the clearance gap; provides a weather seal, minimizes the passage of light and noise, and retards the passage of smoke or flame during a fire. Also see overlapping astragal, split astragal.

astragal front A lock front which is shaped to fit the edge of a door having an astragal molding.

astragal joint A spigot-and-socket joint used on a lead downspout (or the like), where the socket incorporates ornamental moldings called astragals.

astreated Decorated with star-like ornaments.

astylar Columnless; usually describing a façade without columns, pilasters, or the like.

asylum A building or group of buildings that serves as a refuge for the mentally ill.

AT. 1. Abbr. for asphalt tile. 2. On drawings, abbr. for “airtight.”

atadura In Mayan architecture, a façade molding, above and below a continuous horizontal decorative frieze on the exterior of a building.

ataracea Inlaid woodwork of various colors.

ATC 1. On drawings, abbr. for architectural terra-cotta. 2. On drawings, abbr. for “acoustical tile ceiling.”

atelier 1. An artist’s workshop. 2. A place where artwork or handicrafts are produced by skilled workers. 3. A studio where the fine arts, including architecture, are taught.

ATF On drawings, abbr. for “asphalt-tile floor.”

at grade Said of that part of a structure which is at the same elevation as the adjacent finished ground level.

Athenaeum A temple or place dedicated to Athene, or Minerva; specifically an institution founded at Rome by Hadrian for the promotion of literary and scientific studies, and imitated in the provinces.

atlantes See atlas.

atlas, pl. atlantes A figure (or figures) of a man used in place of a column to support an entablature; also called a telamon.

atm Abbr. for “atmosphere.”

atmospheric burner A gas burner in a furnace in which combustion air is supplied at atmospheric pressure.

atmospheric pressure, barometric pressure The pressure exerted by the earth’s atmosphere; under standard conditions equal to 14.7 lb per sq in. (1.01 × 10⁶ pascals) equivalent to the pressure exerted by a column of mercury 29.9 in. (76.0 cm) high.

atmospheric-pressure steam curing Same as atmospheric steam curing.

atmospheric steam curing The steam curing of concrete or cement products at atmospheric pressure, usually at a maximum ambient temperature between 100 to 200°F (40 to 95°C).

atmospheric-type vacuum breaker A backflow preventer containing a float check, check seat, and an air inlet port. As water flows through this device, it causes the float check to rise off a seat, thereby permitting the flow of water. If pressure is lost upstream or if the flow of water is turned off, the float check falls, thereby allowing air to enter the line and preventing backflow.

atomization The formation of tiny droplets or a very fine spray, as produced by impinging jets of air on a small stream of paint in spray painting.

atomizing-type humidifier A humidifier in which tiny particles of water are introduced into a stream of air.

atrio A walled forecourt in California mission architecture.

atriolum 1. In ancient Rome, a small atrium. 2. A small antechamber forming the entrance of a tomb.

atrium 1. The main hall of an ancient Roman house, containing an opening to the sky (compluvium) through which rainwater falls to a tank or cistern below (impluvium). 2. In a contemporary building, a large vertical space, often centrally located, that connects three or more floors and creates a sense of spaciousness.

atrium tetrastylum An atrium, 1, supported by four columns, one at each corner of the impluvium.

attached column An engaged column.

attached garage 1. A garage which has at least one wall (or part of one wall) in common with a building. 2. A garage which is connected to a building, as by a covered porch.

attached house A house that is joined to one (or more) adjacent house(s) by a party wall.

attached pier Same as engaged pier.

attachment plug A device which is inserted into a receptacle to establish the electric connection between the conductors which are wired to the receptacle and the conductors of the flexible cord attached to the plug.

attemperator See coil.

attenuation See sound attenuation.

attenuator See sound attenuator.

Atterberg limits In plastic soils, the water contents (determined by standard tests) which define the boundaries between the different states of consistency of plastic soils. Also see liquid limit, plastic limit, shrinkage limit.

Atterberg test A test for determining the plasticity of soils.

attic 1. A garret. 2. In classic building, a story built above the wall cornice. 3. (cap.) Pertaining to the district of Attica in Greece. 4. The ornamental construction above an entablature; often decorated. 5. The space between the ceiling framing of the topmost story and the underside of the roof framing.

Attic base The base of a column of the Ionic order consisting of an upper torus and a lower torus, with a scotia and two narrow fillets between them.

attic fan A propeller fan used to exhaust the air within an upper space of a house (such as a garret).

attic order Small pillars or pilasters decorating the exterior of an attic, 2.

attic story See attic, 2.

attic tank An open tank which is installed above the highest plumbing fixture in a building (e.g., in the attic) and which supplies water to the fixtures by gravity; the filling of the tank is controlled by a float valve.

Atticurge Said of a doorway having jambs which are inclined slightly inwards, so that the opening is wider at the threshold than at the top.

attic ventilator A mechanical fan, located in the attic space of a residence; usually moves large quantities of air at a relatively low velocity.

attorney-in-fact A person authorized to act for or in behalf of another person or organization, to the extent prescribed in a written instrument known as a power of attorney.

aud Abbr. for auditorium.

audio accumulator An audio listening device used to detect sounds of breaking and entering a building or a secure area within a building. False alarms are minimized by a circuit design that delays activation of an alarm until a predetermined number of sound detections have been “accumulated” within a selected time period.

audio frequency Any frequency of oscillation of a sound wave which is audible; usually in the range between 15 and 20,000 Hz (cycles per second).

audio-visual aids Equipment and/or materials used in training, demonstrations, or teaching, which employ sight and sound simultaneously.

auditorium That part of a theater, school, or public building which is set aside for the audience for listening and viewing.

auditorium plan A plan, 1 employed in church architecture where the plan of the sanctuary somewhat resembles a common plan of a modern auditorium.

auditorium seating Manufactured row chairs for stepped, level, or inclined floors in rooms or areas occupied by an audience.

auditory In ancient churches, that part of the church where the people usually stood to be instructed in the gospel; now called the nave.

auger 1. A hand-held carpenter’s tool for boring holes in wood, similar to, but larger than, a gimlet; has a long steel bit usually not larger than 1 in. (25 mm) in diameter. 2. A rotary drill, usually powered, for cutting circular holes in earth or rock.

auger bit A bit having a square tang, fitted into and rotated by a brace; used for drilling holes in wood.

augered pile A concrete pile which is cast-inplace in a hole drilled by an auger; may be belled at the bottom; suitable in dry soil.

Augustaeum A building or temple dedicated to the deified Augustus.

aula In ancient architecture, a court or hall, esp. an open court attached to a house.

auleolum A small church or chapel.

aumbry See ambry.

aureole A pointed oval frame or glory around the head or body of a sacred figure; the radiance surrounding it. (See illustration p. 66.)

auricular Said of the shape of an ornament of organic and dynamic forms that resemble the ear.

authority See administrative authority.

authority having jurisdiction A federal, state, local, or other regional department, or an individual such as a fire chief, fire marshal, chief of a fire prevention bureau (or labor department or health department), building official, electrical inspector, or other individual having statutory authority. For insurance purposes, the “authority having jurisdiction” may be an insurance inspection department or rating bureau, or other representative of an insurance company. In many circumstances the property owner or a delegated agent assumes the role of the authority having jurisdiction; at government installations, the commanding officer or departmental official may be the “authority having jurisdiction.”

AUTO On drawings, abbr. for “automatic.”

autoclave A pressure vessel in which an environment of steam at high pressure may be produced, usually at a high temperature; used in the curing of concrete products and in the testing of hydraulic cement for soundness.

autoclave curing Steam curing of concrete products, sand-lime brick, asbestos cement products, hydrous calcium silicate insulation products, or cement in an autoclave at maximum ambient temperatures generally between 340 and 420°F (170 and 215°C).

autoclaved aerated concrete A lightweight concrete usually made by adding aluminum powder or calcium carbide to concrete mortar which is subject to autoclave curing.

autoclaving cycle 1. In autoclave curing, the time interval between the start of the temperature-rise period and the end of the blowdown period. 2. A schedule of the time and temperature-pressure conditions of periods which make up the cycle.

auto court A motel.

autogenous healing A natural process of closing and filling cracks in concrete or mortar while it is kept damp.

autogenous volume change The change in volume produced by continued hydration of cement, exclusive of effects of external forces or change of water content or temperature.

autogenous welding A type of welding in which the metals are usually united without the use of flux, 1.

automatic Said of a door, window, or other opening protective device that is so constructed and arranged that, when actuated by a predetermined temperature or rise in temperature, it will operate as intended.

automatic batcher A batcher for concrete which is actuated by a single starter switch, opens automatically at the start of the weighing operations of each material, and closes automatically when the designated weight of each material has been reached.

automatic circuit breaker See circuit breaker.

automatic circuit recloser A self-controlled device for automatically interrupting and reclosing an alternating current circuit with a predetermined sequence of opening and reclosing, followed by resetting, hold closed, or lockout operation.

automatic closing device See closing device.

automatic control valve A valve designed to control the flow of steam, water, gas, or other fluids, by means of a variable orifice which is positioned by an operator in response to signals from a sensor or controller.

automatic door 1. A power-operated door that closes when subject to an abnormally high ambient temperature, an unusual rate of temperature rise, or an abnormal smoke condition. 2. A power-operated door that opens when a person or automobile approaches.

automatic door bottom A movable plunger, in the form of a horizontal bar at the bottom of a door, which drops automatically when the door is closed; when closed, a horizontal protruding operating rod strikes the door jamb, thereby actuating the plunger, sealing the threshold and reducing noise transmission.

automatic dry-pipe sprinkler system A sprinkler system in which the piping up to the sprinkler heads is either filled with compressed air or air at atmospheric pressure; the water supply is controlled by an acceptable dry-pipe valve; also see dry-pipe sprinkler system.

automatic dry standpipe system A stand-pipe system in which all piping is either filled with compressed air or air at atmospheric pressure; the water enters the system through a control valve that is actuated either automatically by a reduction of air pressure within the system or by the manual activation of a remote control located at each fire-hose station.

automatic elevator, self-service elevator An elevator which starts and stops automatically in response to the pushing of a button at one of the landings or in the car.

automatic fire-alarm system A fire-alarm system which detects the presence of a fire and automatically initiates a signal indicating its detection.

automatic fire detector An alarm-initiating device that automatically detects heat, smoke, or other products of combustion.

automatic fire door A fire door that automatically closes a space when the temperature within the space reaches a predetermined value, or when there has been a significant increase in the rate of temperature rise, smoke, or other products of combustion within the space.

automatic fire-extinguishing system An approved system of devices and equipment that automatically detects a fire and then discharges an approved fire-extinguishing agent onto or in the area of the fire.

automatic fire pump A pump which provides the required water pressure in a fire standpipe or sprinkler system; when the water pressure in the system drops below a preselected value, a sensor causes the pump to start, and to stop the pump when the pressure is restored.

automatic fire-suppression system An engineered system using carbon dioxide (CO₂), a foam wet or dry chemical, a halogenated extinguishing agent, or a clean extinguishing agent, in an automatic sprinkler system to detect and automatically suppress a fire through fixed piping and nozzles.

automatic fire vent 1. A device installed in the roof of a large single-story building which operates automatically in the event of fire, providing an opening to the outdoors; removes smoke and confines the fire so that it can be fought more effectively. 2. See smoke and fire vent.

automatic flushing system A water tank system which provides automatically for the periodic flushing of urinals or other plumbing fixtures, or of pipes having too small a slope to drain effectively.

automatic gas shutoff device In a gas-fired water heater, a device that shuts off the gas supply if the water temperature in the heater exceeds a predetermined limit.

automatic load shedding The automatic disconnection of a part of the electrical load in a building when there is an outage of the main power supplied to the building; this action reduces the total load placed on an emergency power generator.

automatic operation In an elevator: an operation whereby the starting of the elevator car is effected in response to the momentary actuation of operating devices at the landing, and/or in response to any automatic starting mechanism; and whereby the car is stopped automatically at the landings.

automatic operator A power-operated door-activating device and control, actuated by approaching traffic or a remote switch.

automatic pilot See safety shutoff device.

automatic smoke alarm system An alarm system whose smoke detectors initiate and transmit an alarm automatically.

automatic smoke vent See smoke and fire vent.

automatic sprinkler A sprinkler head having a nozzle which is normally closed, but opens when exposed to a predetermined quantity of heat—either by the melting of a fusible element or by the rupturing of a liquid-filled glass bulb.

automatic sprinkler system 1. A fire-protection sprinkler system connected to a suitable water supply; designed to provide an immediate and continuous flow of water automatically in case of fire. 2. A fire sprinkler system that reacts to fire without the need for human intervention; a type of automatic fire-protection sprinkler system.

automatic threshold closer Same as automatic door bottom.

automatic transfer switch 1. A combination of an electrically operated, double-throw transfer switch and a control panel. Under normal circumstances, the connected load is energized from the utility source. Upon failure of this source, the transfer switch automatically connects the load to an emergency power generator until power supplied by the utility is restored, at which time it reconnects the load to the utility source. 2. In an electric circuit, a switch which automatically transfers a specific load from the normal source to an emergency source if the former fails or if the voltage of the normal source drops below a preset minimum.

automatic water supply A water supply system whose operation is not dependent on any manual setting of any items of equipment, such as operating valves, starting pumps, or connectors.

automatic wet-pipe sprinkler system A sprinkler system in which all piping and sprinkler heads, at all times, are filled with water under pressure; the system discharges immediately when a sprinkler head operates, and the water continues to flow until the system is shut off.

auto-suppression system A British term for a protection system that activates automatically when a fire is detected; an automatic sprinkler system.

aux Abbr. for “auxiliary.”

auxiliary dead latch, auxiliary latch bolt, deadlocking latch bolt, trigger bolt A supplementary latch in a lock which automatically deadlocks the main latch bolt when the door is closed.

auxiliary energy subsystem An energy source (other than the sun), used to supplement or provide backup for the output provided by a solar energy system.

auxiliary heat The additional heat which is supplied by a conventional heating system in a house when its solar energy system fails to deliver sufficient energy to heat the house to a comfortable temperature. See auxiliary energy subsystem.

auxiliary heating fraction The ratio of auxiliary heat to the total heating requirements.

auxiliary loads All dynamic loads other than the basic design loads which a building must sustain.

auxiliary rafter Above a principal rafter, a second principal rafter, occasionally used in a large queenpost truss.

auxiliary reinforcement In a prestressed structural member, any reinforcement in addition to that whose function is prestressing.

auxiliary rim lock A secondary or extra lock that is surface-mounted on a door to provide additional security.

auxiliary rope-fastening device A device attached to an elevator car, to a counterweight, or to the overhead dead-end rope-hitch support; automatically supports the car or counterweight in case the fastening for the wire rope (cable) fails.

available short-circuit current The maximum electric current delivered by the electric power system to a fault at a given point in a circuit.

avalanche protector A barrier that prevents loose material from sliding into the tracks or wheels of any type of excavation or digging machine.

avant-corps That part of a building which projects prominently from the main mass, e.g., a pavilion.

AVE On drawings, abbr. for “avenue.”

aventurine Glass (or glazes) containing colored spangles of nonglassy material.

avenue 1. A wide street, usually planted with trees; generally straight. 2. A way of approach or access.

average bond stress The force in a steel reinforcing bar divided by the product of its perimeter and its embedded length.

average concrete Concrete that is made without artificial aggregates or admixtures; its strength is not established by tests but is assumed to be the value derived from its water-cement ratio.

average-end-area method A procedure for calculating the volume of earthwork between two cross sections; the cross-sectional areas are averaged and multiplied by the distance between cross sections to determine the volume.

average frequency of occurrence The average number of years between storms that will produce rainfall rates equaling or exceeding a given amount; sometimes called the “return period.”

average grade Within a building construction site, the arithmetic average of the elevations of various ground surfaces within the site.

average haul The average distance that a grading material is moved from cut to fill.

AVG On drawings, abbr. for “average.”

avodire, white mahogany A west African wood, pale yellow to white in color; soft to hard; light in weight to moderately heavy; frequently ribbon-striped. Used for interior finish, plywood, and paneling.

AW Abbr. for “actual weight.”

A/W Abbr. for “all-weather.”

award A communication from an owner accepting a bid or negotiated proposal. An award creates legal obligations between the parties.

A-weighted sound level The sound level measured with a sound-level meter using A-weighting, which alters the sensitivity of the soundlevel meter with respect to frequency so that the sound-level meter is less sensitive at frequencies where the ear is less sensitive; usually used in specifying permissible sound levels in buildings.

AWG On drawings, abbr. for American wire gauge.

AWI Abbr. for “Architectural Woodwork Institute.”

awl A pointed tool used for piercing holes in thin wood, hardboard, etc.

awning A roof-like covering of canvas, or the like, often adjustable, over a window, door, etc., to provide protection against the sun, rain, and wind.

awning blind A blind which is hinged at the top; can swing outward and be fixed in position by a stay.

awning window A window consisting of a number of top-hinged horizontal sashes one above the other, the bottom edges of which swing outward; operated by one control device.

AWPA Abbr. for “American Wood-Preservers’ Association.”

AWS 1. Abbr. for “all wood screws.” 2. Abbr. for “American Welding Society.”

A.W.W.I. Abbr. for “American Wood Window Institute.”

ax 1. A sharp-edged steel tool for splitting wood, hewing timber, etc. 2. An axhammer.

axed arch An arch which is constructed of bricks that have been roughly cut into a wedge shape.

axed brick, rough-axed brick A brick, shaped with an ax, that has not been trimmed; when laid, the joints for such bricks are thicker than those for gauged brick.

axed work (Brit.) A hand-dressed stone surface showing toolmarks made by an ax, pick, or bushhammer.

axhammer An ax for spalling or dressing rough stone; has either one cutting edge and one hammer face or two cutting edges.

axial-flow fan 1. One of the following types of fans: vaneaxial, tubeaxial, or propeller. Such fans impart energy to the air by giving it a twisting motion. They are specified by blade shape, ratio of hub-to-tip diameter, pitch of the blades, and number of blades. Guide vanes may be added to straighten the flow and increase the efficiency. 2. See centrifugal fan.

axial force See axial load.

axial force diagram In statics, a graphical representation of the axial load acting at each section of a structural member, plotted to scale and with proper sign as an ordinate at each point of the member and along a reference line representing the length of the member.

axial load, axial force The resultant longitudinal internal component of force which acts perpendicular to the cross section of a structural member and at its centroid, producing uniform stress.

axis A straight line indicating center of symmetry of a solid or plane figure.

axle pulley See sash pulley.

axle-steel reinforcing bar A reinforcing bar fabricated from carbon-steel axles of railroad cars.

Axminster carpet A carpet having pile which is attached to the carpet backing by inserting the tufts by rows between the warp threads and then binding them by means of the filling; this method of carpet construction permits intricate design and almost any number of colors to be used.

axonometric projection A form of orthographic projection in which a rectangular object, projected on a plane, shows three faces. One of two general divisions of pictorial projection (the other being oblique projection); often divided into three types: isometric, dimetric and trimetric.