D

d Abbr. for penny (nail size).

D Abbr. for “down.”

D&CM Abbr. for “dressed and center matched.”

D&H In the lumber industry, abbr. for “dressed and headed.”

D&M In the lumber industry, abbr. for “dressed and matched.”

D&MB Abbr. for “dressed and matched beaded.”

D&SM Abbr. for “dressed and standard matched.”

D1S Abbr. for “dressed one side.”

D2S Abbr. for “dressed two sides.”

D2S&CM Abbr. for “dressed two sides and center matched.”

D2S&M Abbr. for “dressed two sides and matched.”

D2S&SM Abbr. for “dressed two sides and standard matched.”

D4S Abbr. for “dressed on four sides.”

dabber A soft brush used to apply varnishes.

dabbing, daubing Dressing a stone surface with a special pointed tool to produce a pitted appearance.

DAD On drawings, abbr. for double-acting door.

dado 1. The middle portion of a pedestal between the base (or the plinth) and the surbase (or the cornice, cap, or entablement); also called die. 2. The middle part (sometimes all parts) of a protective, ornamental paneling applied to the lower walls of a room above the baseboard. 3. A rectangular groove cut across the full width of a piece of wood to receive the end of another piece.

dado, 3

dado cap A chair rail or cornice at the top of a dado.

dado groove Same as dado, 3.

dado head A power-driven rotary cutter, usually consisting of two identical circular saws with a chipper between them; used in woodworking for cutting flat-bottomed grooves.

dado joint See housed joint.

dado rail A chair rail.

dagger A small decorated tracery motif in the form of a distorted cusped lancet, with the foot pointed; a pointed oval-shaped opening in the tracery.

dagoba In Buddhist architecture, a monumental structure containing relics of Buddha or of some Buddhist saint.

dagoba in Sri Lanka

daily noise dose See noise dose.

dairy See milk house.

dais A raised platform reserved for the seating of speakers or dignitaries. (See illustration p. 296.)

dais

dalan In Persian and Indian architecture, a veranda, or sometimes a more stately reception hall, more or less open to the weather, with a roof carried on columns, or the like.

dallan Same as dalan.

dalle A slab or large tile of stone, baked clay, etc., esp. a tile of which the surface is incised or otherwise ornamented, such as the medieval sepulchral slabs set in the pavement and walls of churches.

damages See liquidated damages.

dammar, damar, dammer, gum dammar A naturally occurring resin; useful in paints and varnishes because of its light color.

damp check See damp course.

damp course, damp check, dampproof course In masonry, an impervious horizontal layer of material (as tile, dense limestone, metal, etc.) to prevent the capillary entrance of moisture from the ground or a lower course, but used also below copings, above roof level in chimneys, and elsewhere to stop downward seepage.

damper 1. A device used to vary the volume of air passing through an air outlet, inlet, or duct; it does not significantly affect the shape of the delivery pattern. 2. A pivoted cast-iron plate at fireplace throat, i.e., between fireplace and smoke chamber, to regulate draft. 3. Same as fireplace damper.

damper, 1

butterfly damper, 1

damping The dissipation of energy with time, e.g., the dissipation of energy in a mechanical system whose free oscillations decrease with time, resulting in a decrease in its amplitude of vibration.

damping material A viscous material applied to a vibrating surface, such as a metal panel, to reduce the noise which it radiates.

dampproof course See damp course.

dampproofing 1. A treatment of concrete or mortar to retard the passage or absorption of water, or water vapor, either by applying a suitable coating to exposed surfaces or by using a suitable admixture. 2. A damp course. 3. Applying a water-impervious material to a surface, such as a wall, to prevent the penetration of moisture.

dampproofing, 3

damp-proof membrane See membrane waterproofing.

dancers Colloquial term for stairs.

dancette See chevron, 2; also see zigzag.

dancing step, danced step See balanced step.

dancing winder See balanced step.

Danish knot Same as Runic knot.

dao, paldao A variegated colored wood from the Philippines and New Guinea, having shades of gray, green, yellow, brown, and pink with dark streaks; moderately hard, heavy; used for cabinets, plywood, and interior finish.

dap A notch in a timber for receiving another timber or into which the head of a pile is fitted.

dapped beam Said of a beam (or girder) having a notch to receive another notched beam.

dar 1. In Indian and Persian architecture, a gateway. 2. In Oriental architecture, a dwelling.

darby, derby slicker 1. A float tool used in plastering, either wood or metal, about 4 in. (10 cm) wide and about 42 in. (approx. 1 m) long, with two handles; used to float or level the plaster base coat prior to application of the finish coat, or to level the plaster finish coat before floating or troweling. 2. A hand-manipulated straightedge usually 3 to 8 ft (1 to 2.5 m) long, used in the early-stage leveling operations of concrete finishing to supplement floating.

dart See egg-and-dart molding; anchor, 8.

dash-bond coat A thick slurry of portland cement, sand, and water dashed on surfaces with a paddle or brush to provide a base for a subsequent plaster coat.

dashed finish An exterior wall finish, obtained by throwing small pebbles against a smooth mixture of cement while it is still wet. Also see rock dash.

date of agreement The date stated on the face of the agreement. If no date is stated, it may be the date on which the agreement is actually signed, if this is recorded, or it may be the date established by the award; also referred to as the contract date.

date of commencement of the work The date established in a notice to proceed or, in the absence of such notice, the date of the agreement or such other date as may be established therein or by the parties thereto.

date of substantial completion The date certified by the architect when the work, 1 or a designated portion thereof is sufficiently complete, in accordance with the contract documents, so the owner may occupy the work or designated portion thereof for the use for which it is intended.

date stone A stone, imbedded in the walls of many old buildings, carved with the date of completion of the structure.

date stone

datum A level surface or point to which other levels are related; a reference in measuring elevations.

datum dimension A dimension that exactly locates a reference point, reference line, or reference plane.

datum line Same as reference line.

datum point In surveying, the point to which all other points are related.

daub 1. A material such as clay, mortar, mud, or plaster (often mixed with straw), used as infilling between logs, as a coating over walls, or as plaster in wattle-and-daub. 2. To coat roughly with plaster or mud.

daubing 1. See dabbing. 2. A rough coating of plaster given to a wall by throwing plaster against it.

davit A movable crane, 1 that projects over the side of a building.

day One division in a window, as in a large church window.

day gate In a bank, an interior grille door to a safe-deposit vault; used when the main vault door is open.

daylight factor The ratio of the illumination at a point on a given plane to the illumination on a horizontal plane from the whole of an unobstructed sky of assumed or known luminance distribution; a measure of the daylight illumination at that point.

daylight glass A bluish glass, often colored with cobalt, used with incandescent lamps to produce the effect of daylight by absorbing excess radiation in the red part of the light spectrum.

daylighting Lighting of the interior of a building by natural means; for example, by windows or skylights.

daylight lamp 1. Any type of lamp which produces light whose spectral distribution approximates that of a specified daylight condition. 2. See incandescent daylight lamp.

daylight saturation level Said of the condition where the illumination provided by daylight equals or exceeds the illumination provided by artificial lighting.

daylight width, sight size, sight width The width of a glazed opening which admits light.

dB Abbr. for decibel.

dB(A) A unit of sound-level; a reading taken on the A-scale of a sound-level meter.

DB. Clg. Abbr. for “double-headed ceiling.”

DBL On drawings, abbr. for “double.”

DBT Abbr. for dry-bulb temperature.

dc, d-c, d.c., DC Abbr. for “direct current.”

D-crack, D-line crack 1. In concrete surfaces, one of many fine, closely spaced cracks; often in random patterns. 2. In highway slabs, one of the fine cracks parallel to the edges, joints, and larger cracks or cutting diagonally across the corners.

DD On drawings, abbr. for Dutch door.

deactivation The reduction or removal of the corrosive qualities of water, usually by passing the water through a deactivator while hot.

deactivator A tank containing iron filings which removes active oxygen and other corrosive elements from water that passes through it.

dead Descriptive of electric wiring which is not connected to a source of voltage.

dead-air space Unventilated air space within a structure, as in a shaft, ceiling, or hollow wall.

dead bolt A type of door lock; the bolt, which is square in cross section, is operated by the door key or a turn piece.

dead bolt

dead-burnt gypsum See anhydrous calcium sulfate.

dead door Same as blank door.

dead end 1. A length of pipe leading from a soil, waste, or vent pipe, building drain, or building sewer, which is terminated by a plug, cap, or other closed fitting; there is no circulation in this length of pipe, and no waste from a plumbing fixture is fed into it. 2. The point of fastening in a running rope system where the other end is fastened to a rope drum. 3. In concrete work, the end opposite that to which a load is applied. 4. A portion of a corridor in which the travel to an exit is in one direction only.

dead-end anchorage Anchorage at the end of a tendon which is opposite the jacking end.

deadening The use of damping material.

dead flue A flue that has been bricked-up or otherwise sealed off.

dead-front Descriptive of a piece of electric equipment so constructed that there are no parts which can be touched from the front of the assembly that are at a voltage different from that of the earth.

dead knot A knot that has lost its fibrous connection with the surrounding wood; it can easily loosen and fall out or be knocked out.

deadlatch Same as night latch.

dead leaf Same as standing leaf.

dead leg Same as dead end.

dead level Said of a roof surface having a declination of less than 2%.

deadlight See fixed light.

dead load 1. The weight of a structure itself, including the weight of fixtures or equipment permanently attached to it. Compare with live load. 2. The load imposed on a pipe located in a trench and covered by infill; depends on the depth and width of the trench, and the density and character of the infill material.

deadlock 1. A lock equipped with a dead bolt only. 2. A lock in which a bolt is moved by means of a key or thumb turn, and is positively stopped in its projected position.

deadlocking latch bolt See auxiliary dead latch.

deadman A buried concrete block, log, plate, or the like, which serves as an anchorage, e.g., as an anchor for a tie to a retaining wall; depends on its own weight and passive pressure from the soil to hold it in place.

dead man anchor Same as guy anchor.

dead parking Long-term, unattended storage of a vehicle.

dead-piled Descriptive of lumber or panels stacked without spacers.

dead room A room characterized by an unusually large amount of sound absorption.

dead sand Sand that may be used as an underneath course for a finished layer of loose stones or gravel.

dead shore An upright piece of heavy timber used as a prop or support for a dead load during structural alterations to a building, esp. one of two supports for a needle, 1.

dead-soft temper The temper of sheet copper used for roofing.

dead wall A wall whose entire surface is unbroken by a door, window, or any other opening; a blank wall.

dead weight See dead load.

dead window Same as blank window.

deadwood 1. Dead tree limbs or branches. 2. Wood from dead trees.

deal 1. (US) Pine or fir lumber cut to a specified size, usually at least 3 in. (76 mm) thick and 9 in. (229 mm) wide. 2. (Brit.) Square-sawn softwood lumber, 1 in. (47.6 mm) to 4 in. (101.6 mm) thick and 9 in. (228.6 mm) to under 11 in. (279.4 mm) wide.

dealbatus A coating of white cement or stucco (albarium opus), employed extensively by the ancient Romans as an ornamental facing to conceal rough stones or brickwork.

deambulatory 1. An aisle extending around the apse of a church; an apse aisle. 2. The ambulatory of a cloister, or the like.

deambulatory, 1

de-bonding In pretensioned construction, a procedure used to prevent specific tendons from becoming bonded to the concrete for a specified distance from the ends of the flexural members.

debt service The periodic repayment of a loan, including both accrued interest and a portion of the principal.

DEC On drawings, abbr. for “decimal.”

decal, decalcomania Colored designs on special paper for transfer to unglazed or glazed ceramic ware or glass.

decani side The south side of a church, i.e., the side on the right of one facing the altar.

decarburization The loss of carbon at the surface of carbon steel when it is heated for processing or in modifying its mechanical properties.

decastyle A building having a portico of ten columns, or rows of ten columns.

decastyle

decatetrastyle Said of a Classical building portico having fourteen columns in the front or end row.

decay See brown rot, white rot.

decayed knot See unsound knot.

decay rate 1. At a given frequency, the rate at which the sound level in a room decreases after a source stops emitting sound; expressed in decibels per second (dB/s). 2. Of sound waves in an enclosed space, the rate at which the sound-pressure level of reverberation decreases; usually expressed in decibels per second. 3. Of a vibrating mechanical system, the rate at which some stated characteristic (such as the amplitude of vibration) decreases with time.

decenter To remove centering or shoring.

decibel The unit in which the level, 4 of various acoustical quantities is expressed.

deciduous Descriptive of trees or shrubs, usually of temperate climates, that shed their leaves annually; characteristic of most hardwoods and a few softwoods.

deck 1. The flooring of a building or other structure. 2. A flat open platform, as on a roof. 3. The structural surface to which a roof covering system is applied. 4. The top section of a mansard or curb roof when it is nearly flat.

deck clip 1. A metal fastening device used to attach roof-deck material to a structural frame. 2. An H-shaped metal piece used between adjacent sheets of plywood decking to limit uneven deflections. 3. Any device used to fasten thermal insulation to a roof-deck.

deck curb A curb around the edge of a roof-deck.

deck dormer A hipped dormer that has been truncated so that it has a flat, horizontal roof.

deck drain A drain that is similar in all respects to a roof drain except that it generally has a flat strainer and is located in a flat area such as a patio, walkway, etc.

decking 1. The thick boards or planks used as structure flooring, usually for long spans between joists or for heavy service; also called planking. 2. Light-gauge sheets of metal which are ribbed, fluted, or otherwise integrally stiffened for use in constructing a floor or roof. 3. See roof decking.

decking, 1

deck-on-hip A flat roof capping a lower roof that is hipped.

deck paint An enamel having a high degree of resistance to mechanical wear; esp. used on surfaces such as porch floors.

deck roof, deck-on-hip roof A hipped roof that has been truncated to form a flat-topped roof.

deck screens Two or more screens, 3 placed one over the other.

Deconstructivist architecture Architecture that seeks to arrive at new forms of expression by turning away from structural restraints and functional and thematic hierarchies, and toward often nonrectangular, fantastic, and seemingly disjointed designs. Such work often represents an application of the philosophical theories of Jacques Derrida in France, who sought to arrive at new insights in literature by breaking apart literary texts into their contradictory and hidden components of meaning; this philosophy has been applied in the late 20th century to architectural structures usually called deconstructivist architecture.

decor The combination of materials, furnishings, and objects used in interior decorating to create an atmosphere or style.

Decorated style The second of the three phases of English Gothic architecture, from ca. 1280 to after 1350, preceded by Early English style and followed by the Perpendicular style; characterized by rich decoration and tracery, multiple ribs and liernes, and often ogee arches. Its early development is called Geometric; its later, Curvilinear.

Decorated style

decorative block A concrete masonry unit having special treatment of its exposed face shell for architectural effect; such treatment may consist of distinctive aggregates (with or without additional coloring) or of beveled recesses (for patterned appearance when illuminated obliquely).

decorative half-timbering Timbers or boards that provide the appearance of half-timbered construction but whose function is ornamental rather than structural; also called false half-timbering.

decorative paint A paint which conceals the covered surface and provides a decorative and protective coating.

decorative stone Stone that functions as architectural decoration.

decoupling The separating of building elements to reduce the transfer of heat, sound, or physical loads from one element to another.

dedicated street A street, the title of which has been yielded by an owner, either permanently or temporarily, to the authorities for use of the street by the general public.

dedication cross A cross painted or carved on the wall of a church to indicate any one of the twelve spots touched with chrism by the bishop at the consecration ceremony of the church.

deductible On a building project, a type of insurance policy stipulating that in the event of loss, the insured is liable for a specified initial amount and the insurance company is liable for the amount above that figure, up to the insured amount.

deduction The amount deducted from the contract sum by a change order.

deductive alternate An alternate bid resulting in a deduction from the same bidder’s base bid. Also see alternate bid.

deed Any duly attested, written document executed under seal and delivered to effect a transfer, bond, or contract, such as a conveyance of real property or interest therein.

deed restriction A limitation on the use of land, which is set forth in a deed conveying the restriction.

deep bead See draft bead.

deep beam footing A tie beam, 2 for carrying heavy loads; resists shear forces.

deep cutting, deeping The resawing of timber lengthwise, parallel to the faces.

deep foundation A continuous foundation which provides a footing by filling a deep trench with concrete.

deeping See deep cutting.

deep-seal trap, antisiphon trap In plumbing, a U-shaped trap having a seal, 3 of 4 in. (10 cm) or more.

deep well A well that draws water from beneath an impermeable stratum.

default A substantive failure to fulfill a material obligation under a building contract.

defect In wood, a fault that may reduce its durability, usefulness, or strength.

defective work Work not complying with the contract requirements. See nonconforming work.

deferred maintenance The postponement of maintenance for any reason, such as the need to keep equipment in full-time operation, the lack of funds for repair, or the unavailability of parts.

deferrization The treatment of water to remove soluble compounds of iron.

deficiencies See defective work.

deflagration Burning; the rapid combustion of a substance, attended with an extremely sudden evolution of flame and vapor.

deflected shape Said of the profile of a structure that is deformed when it is loaded.

deflected tendons In a concrete member, tendons which have a curved trajectory with respect to the gravity axis of the member.

deflection 1. Any displacement in a body from its static position, or from an established direction or plane, as a result of forces acting on the body. 2. The deformation of a structural member as a result of loads acting on it.

deflection angle In surveying, a horizontal angle measured from prolongation of the preceding transit line to the next line; recorded as “right” if clockwise rotation and “left” if counterclockwise.

deflection limitation The maximum deflection permitted by code or by good practice.

deflectometer A device for measuring the amount of bending in a beam induced by a transverse load.

deformation Any change of form, shape, or dimensions produced in a body by a stress or force, without a breach of the continuity of its parts.

deformed bar, deformed reinforcing bar A steel reinforcing bar which is manufactured with surface deformations to provide a locking anchorage with surrounding concrete.

deformed bars

deformed metal plate A corrugated (or otherwise deformed) metal plate used in construction to form a vertical joint and to provide a mechanical interlock between the adjacent sections.

deformed reinforcement In reinforced concrete, reinforcement, 1 consisting of reinforcing bars, reinforcing rods, deformed wire, welded wire fabric, and welded deformed wire fabric.

deformed tie bar A deformed bar used as a tie bar to hold two slab elements in close contact.

defrosting The removal of accumulated ice from a cooling element.

defurring Same as deliming.

DEG On drawings, abbr. for “degree.”

degradation Disintegration of a paint film by heat, moisture, sunlight, or natural causes.

degrades Pieces of lumber which, during reinspection, prove to be of lower quality than originally classified.

degree 1. A step, as of a stair. 2. A stair, or set of steps.

degree-day A unit used in estimating the fuel consumption for a building; equal to the number of degrees that the mean temperature, for a 24-hour day, is below the “base temperature”; the base temperature is taken as 65°F (18.3°C) in the US and as 60°F (15.6°C) in Great Britain.

degree of compaction A measure of the packing of soil. Also see voids, 2.

degree of saturation Same as percent saturation.

dehumidification 1. The condensation of water vapor from air by cooling below the dew point. 2. The removal of water vapor from air by chemical or physical methods.

dehumidifier Any device or apparatus for removing moisture from air.

dehydration The removal of water vapor from air by the use of absorbing or adsorbing materials.

deionization See cation-exchange softening.

DEL On drawings, abbr. for “delineation.”

delamination A failure in a laminated structure characterized by the separation or loss of adhesion between plies, as in built-up roofing or glue-laminated timber.

delay cap A blasting cap that explodes (as the result of an electrical current through it) at a set time after activation.

deletion A change order that reduces the scope of work originally defined in the contract documents.

deliming The removal of scale, 8 on the inside of boilers or hot water heaters.

deliming tee A tee, 2 provided at the entry and outlet of a water heater to permit the temporary installation of deliming equipment periodically.

deliquescence The absorption of water from the air by certain salts in plaster or brick; results in dark, damp areas on the surface.

delivery hose A hose through which fresh concrete, mortar, or the like is pumped.

delivery point See point of service.

delphinorum columnae The two columns at one end of the spina of an ancient Roman circus, on which marble figures of dolphins were placed.

delta connection A connection arrangement of a three-phase electrical transformer; the three windings are connected in series forming a closed circuit in the shape of a Greek capital delta. Compare with wye connection.

delta connection

delubrum 1. In ancient Roman architecture, a sanctuary or temple. 2. The part of a classical temple containing the altar or a statue of the deity; the most sacred part of the temple.

deluge sprinkler system 1. A dry-pipe sprinkler system with open heads; is controlled by an automatic valve which is activated by smoke- or heat-sensitive devices; provides a dense, uniform coverage of water over the protected area. 2. A fire sprinkler system using open sprinklers (i.e., open sprinkler heads). When the fire detection system is activated, the deluge valve opens, resulting in water being sprayed simultaneously from all of the open sprinklers; usually used for protection against rapidly spreading high-hazard fires.

deluge valve A special valve that, under normal conditions, holds back the water from the piping of a deluge sprinkler system; a separate fire detection system is used to open this valve.

DEL V symbol for deluge valve.

demand 1. The electric load on a system, integrated over a specific time interval; usually expressed in watts or kilowatts. 2. The volume of gas per unit time (usually expressed in cubic feet per hour or liters per second) or the amount of heat (usually expressed in Btu per hour or mega-joules per hour) required for the operation of one or more gas appliances. 3. The rate of flow of water, usually expressed in gallons per minute (liters per second), furnished by a water supply system to various types of plumbing fixtures and water outlets under normal conditions.

demand factor The ratio of the maximum demand of a system to the total connected load of the system.

demand mortgage loan A call loan which is secured by a mortgage.

demand surcharge An additional charge imposed by an electrical utility for electricity used during periods of peak demand.

demesne All lands belonging to the lord of a manor.

demi-bastion In military architecture, a bastion constructed of one face, 1 and one flank. Also called a half-bastion.

demi-berceau A half tunnel-vault.

demicolumn Same as half column.

demilune Same as ravelin.

demimetope A half, or incomplete, metope in a Doric Frieze.

demi-relief, demi-relievo Same as mezzorelievo.

demising wall Any wall that separates one tenant’s space from that of another tenant.

demographic study A study of the size, distribution, and composition of, and changes within, a specified population group.

demolition The systematic destruction of a building, all or in part.

demountable partition, relocatable partition A nonload-bearing partition of dry construction, assembled from prefabricated components, which can be installed, removed, and then reinstalled at a different location; may be full height, from floor to ceiling, or partial height.

demountable partitions

demurrage A charge made by shippers for the time exceeding that normally allowed for loading and/or unloading of building components or materials delivered by railroad, truck, or ship.

den An indoor retreat, usually small, for work or leisure. Also see chamber, 1.

dendrochronology The dating of old timbers by the study of their annual ring patterns of growth.

dendrology The branch of botany involving the study of trees and shrubs.

dense concrete Concrete containing a minimum of voids.

dense-graded aggregate An aggregate graded to produce low void content and maximum weight when compacted.

densified impregnated wood See compressed wood.

density The degree of aggregation; the quantity of any entity distributed over an area per unit of areal measure, e.g., persons per acre, families per acre, or dwelling units per square mile.

density control The control of the density of concrete in field construction to ensure that specified values, as determined by standard tests, are obtained.

density rules Methods that estimate the density of wood based on the amount of summerwood and its rate of growth.

denticulated, denticular Ornamented with dentils.

dentil One of a band of small, square, toothlike blocks forming part of the characteristic ornamentation of the Ionic, Corinthian, and Composite orders, and sometimes the Doric.

Ionic dentils

dentil band 1. A molding that occupies the position of a row of dentils in classical architecture. 2. A course of masonry that resembles a row of dentils; for example, in brickwork, the toothlike effect produced by the projection of alternate headers and smaller blocks.

Department of Housing and Urban Development (HUD) An agency of the US government that administers provisions of the various housing acts that have been passed by Congress.

dependency A subsidiary building near or adjoining a principal structure.

depeter Same as depreter.

depolished glass Any glass having a diffuse surface, usually produced by etching, sandblasting, etc.

deposited metal The filler metal that is added during a welding operation.

deposit for bidding documents Monetary deposit required to obtain a set of construction documents and bidding requirements, customarily refunded to bona fide bidders on return of the documents in good condition within a specified time.

depository See bank depository.

depot 1. A place of deposit; a storehouse or warehouse. 2. A railroad station; a building for the accommodation and shelter of passengers and the receipt and transfer of freight by the railroad.

depreciation factor The reciprocal of maintenance factor.

depressed arch A drop arch.

depression storage The quantity of storm water that is lost as a result of minor surface depressions in the ground.

depreter Stucco with a rock dash finish.

DEPT On drawings, abbr. for “department.”

depth gauge A device for measuring the depth of a hole, cutout, groove, recess, etc.; usually consists of a graduated scale which slides through a crosspiece.

depth gauge

depth of fixity The depth below ground level at which the soil firmly holds a pile.

derating The reduction in the normal rating of equipment to account for abnormal environmental conditions to which the equipment may be subject.

derby, derby float See darby.

derrick One of a number of types of hoisting devices, equipped with tackle at their upper ends, that lift building materials at a construction site.

desague In Hispanic architecture, a drainage channel on a wall that discharges rainwater down the side of a building.

descaling Removing scale, 8 that forms on the inside of hot water heaters, boilers, etc.

descriptive specification A specification that provides a written description of the materials, equipment, construction systems, and level of workmanship required on a job. Compare with prescriptive specification and performance specification.

desiccant Any absorbent or adsorbent, liquid or solid, that will remove water or water vapor from a material. In a refrigeration circuit, the desiccant should be insoluble in the refrigerant.

desiccation 1. The use of a desiccant for drying. 2. The use of heated air to remove moisture, as from timber in a kiln.

design 1. To compose a plan for a building. 2. The architectural concept of a building as represented by plans, elevations, renderings, and other drawings. 3. Any visual concept of a man-made object, as of a work of art or a machine.

designated services On a building project, those services that the architect, engineers, and consultants agree to perform.

design/build A construction project in which the owner contracts with a single entity to be responsible for both design and construction.

design class A classification rating that indicates the level of resistance to fatigue of a building component.

design development phase The second phase of the architect’s basic services. In this phase the architect prepares (from the approved schematic design studies, for approval by the owner) the design development documents consisting of drawings and other documents to fix and describe the size and character of the entire project as to structural, mechanical and electrical systems, materials and such other essentials as may be appropriate; the architect also submits to the owner a further statement of probable construction cost.

design documents See structural design documents.

design life The period of time over which a building component or structure is required to perform safely, with an acceptable probability that it will not require replacement or significant repair during that time.

design load 1. The total load on a structural system for the worst combination of loads and forces which it is designed to sustain. 2. In an air-conditioning system, the maximum heat load which it is designed to handle. 3. See design ultimate load.

design occupancy The number of people and/or activities for which an environmental system has been designed.

design phase An early phase of work on a building project in which the design of the project is laid out; usually followed by the construction phase.

design population On a public works project, the maximum number of people for whom the project is designed.

design professional An architect or engineer, or both, duly licensed for professional practice, who may be employed by an owner for the purpose of designing a project.

design strength 1. The load-bearing capacity of a member computed on the basis of the allowable stresses which are assumed in design. 2. The assumed values for the strength of concrete, and the yield stress of steel on which the theoretical ultimate strength of a section is computed.

design ultimate load, factored load In structural design, the working load times the load factor.

desornamentado Said of architecture of 16thcentury Spanish Renaissance architecture that is relatively simple.

de Stijl An architectural movement from about 1917 to 1931, which originated in The Netherlands, that placed emphasis on functionalism, rationalism, and current methods of construction, in contrast to historical precedent and traditional methods of construction. This movement had a significant influence on the development of Modern architecture.

destina 1. A pillar or other support for a building. 2. An aisle or small cell in a church.

destraria A late Latin term for deambulatory.

DET 1. On drawings, abbr. for detail. 2. On drawings, abbr. for “detached.” 3. Abbr. for “double end trimmed.”

detached garage 1. A garage which is completely surrounded by open space. 2. A garage connected to a building by an uncovered terrace.

detached house A house that stands completely alone, not sharing a wall with another house.

detail 1. A minor section of an architectural design or concept. 2. A drawing, at a larger scale, of a part of another drawing, indicating in detail the design, location, composition, and correlation of the elements and materials shown.

detail drawing Same as detail, 2.

detailed estimate of construction cost A forecast of construction cost prepared on the basis of a detailed analysis of materials and labor for all items of work, 1 as contrasted with an estimate based on current area, volume, or similar unit costs.

detectable warning According to the Americans with Disabilities Act, a change in a walking surface that alerts a disabled person to the possibility of a hazard ahead.

detector See sensor.

detention basin In a storm-sewer system, a basin for temporarily storing storm water during periods of peak downpour.

detention door A heavy steel door containing fixed lights of laminated glass protected by bars and muntins of tool-resistant steel; used in prisons and mental hospitals.

detention screen A window screen especially designed for institutions of detention; fabricated of screen mesh which is woven of large stainless steel wires; a massive steel frame holds the mesh under tension.

detention window A metal awning window esp. designed for institutions of detention. The sashes (ventilators, 2) are only 6 in. (15 cm) to 8 in. (20 cm) high and pivot on full-width hardened steel rods about 1 in. (2.5 cm) in diameter.

deterioration Of concrete, the same as disintegration.

deterministic design Design which is based on the mechanical and physical properties of materials, building elements, and structures involved.

detonating cord A flexible cord having a high-explosive center core; when detonated, it then detonates other cap-sensitive explosives with which it is in contact.

detonator A blasting cap, electric blasting cap, electric-delay blasting cap, or nonelectric-delay blasting cap.

detritus Loose material which results from the disintegration of rock.

detritus tank In sanitary engineering, a settling tank through which sewage is passed for the removal of the heavier solids.

detrusion See cleavage, 4.

developed area An area of land upon which improvements have been made.

developed distance The shortest distance between two points that free air would travel as measured horizontally, vertically, or diagonally in a straight line or around corners.

developed length The length of a pipeline measured along the center line of the pipe and fittings.

development 1. A tract of previously undeveloped land which is subdivided for housing and provided with all necessary utilities, such as roads, water, electricity, sewers, etc. 2. A large-scale housing project. 3. Any man-made change to improved or unimproved real estate, including but not limited to dredging, excavation or drilling operations, filling, or paving located within an area of special flood hazard.

development area (Brit.) An area in which the government encourages new and esp. diversified industry in order to promote industrial stability.

development bond stress Same as anchorage bond stress.

development length 1. The minimum length of straight reinforcing bar or reinforcing rod which is required to anchor it in concrete. 2. The length of embedded reinforcement required to develop the design strength at a critical section.

development rights A property owner’s entitlement to develop land in accordance with local land-use regulations.

device In an electric system, a component that is intended to carry, but not consume, electric energy, e.g., a switch.

device function numbers Numbers (assigned by ANSI/IEEE Standard C37.02) that provide a convenient way of indicating the function of various types of electrical devices on drawings or in written material.

devil float, devil, nail float A wooden hand float with nails projecting from each corner; used to roughen the surface of plaster to provide a key for the next coat.

devil float

deviling Scratching or roughening plaster.

devitrification Crystallization in glass.

dewater To remove water from an excavated job site, usually by draining or pumping.

dewatering Pumping water from a site to maintain a dry and stable condition during construction.

dewpoint The temperature at which air becomes saturated with water vapor and below which moisture is likely to condense; varies with the amount of moisture contained in the air.

dextrin, amylin, starch gum A starch-like compound having strong adhesive properties; an amorphous, odorless, sweetish-tasting, white, water-soluble gum; used as a wallpaper adhesive.

DF 1. Abbr. for daylight factor. 2. On drawings, abbr. for drinking fountain.

DFI Abbr. for “Deep Foundations Institute.”

dflct Abbr. for “deflection.”

d.f.u. Abbr. for drainage fixture unit.

DHW Abbr. for double-hung window.

DIA On drawings, abbr. for “diameter.”

diabase Rock having the same composition as basalt, but with larger crystals which are just visible to the unaided eye; also called traprock.

diaconicon 1. Originally a place where the deacons kept the vessels used for the church service. 2. In Greek churches, a sacristy to the right of the sanctuary.

DIAG 1. On drawings, abbr. for diagonal. 2. On drawings, abbr. for “diagram.”

diaglyph 1. A relief engraved in reverse; an intaglio. 2. A sunk relief.

diagonal In a framed structure, an inclined member running across a panel, 7, e.g., as in a truss.

diagonal bond A type of raking bond, in thick masonry walls, consisting of a header course (usually every sixth course) with its bricks laid at a diagonal with the exterior and interior faces.

diagonal brace An inclined structural member in compression and/or tension; usually employed to stabilize a frame against horizontal forces, such as wind.

diagonal braces

diagonal bridging 1. See crossbridging. 2. See bridging. 3. A combination of horizontal bridging and diagonals in the same plane; spans between the top flange of one beam (or joist) and the bottom flange of the adjacent beam (or joist), in a plane perpendicular to both.

diagonal bridging, 2

diagonal buttress One extending at 45° from the right-angle corner of two walls.

diagonal chimney stacks Several brick chimney stacks that are square in cross section and oriented so that diagonals through them form a straight line; usually corbeled and joined at their tops.

diagonal chimney stacks

diagonal crack An inclined crack, usually at about 45° to the center line, beginning at the tension surface of a concrete member.

diagonal grain A defect in lumber, usually the result of careless sawing, in which the wood grain is at an angle to the long dimension.

diagonal joining Decorative work formed by bricks or tiles which are set obliquely and symmetrically with respect to a vertical or a horizontal axis.

diagonal pitch In riveted joints having two or more rows of staggered rivets, the distance from one rivet in one row to the nearest rivet in the next row.

diagonal rib A rib crossing a bay or compartment of a vault on a diagonal.

diagonal sheathing A covering of wallboards nailed to exterior studs or rafters at an angle of approximately 45 degrees.

diagonal sheathing

diagonal slating, drop-point slating A method of laying shingles or slates so that the diagonal of each slate runs horizontally.

diagonal tension In reinforced concrete or prestressed concrete, the principal tensile stress resulting from the combination of vertical and horizontal stresses.

diakonikon An apse or recess at the east end of an early Christian church.

diametral compression test Same as splitting tensile test.

diamicton In ancient Roman architecture, a type of masonry wall construction having a hollow cavity filled with broken material of every description.

diamond-bond pattern Same as diaperwork.

diamond ashlar A rectangular building stone having a face that is pyramidal rather than flat.

diamond drill In exploratory drilling, a rotary drill having a coring bit which is studded with black diamonds.

diamond fret, lozenge fret, lozenge molding A molding consisting of fillets intersecting so as to form diamonds or rhombuses.

diamond light, diamond pane A small pane of glass, either diamond-shaped or square-shaped, and set diagonally in lead cames in a window sash. Also called diamond glass.

two types of diamond frets

diamond lights

diamond matching, four-piece butt matching A method of cutting and piecing four adjacent, square-cut pieces of wood veneer so that a diamond pattern results at the center.

diamond-mesh lath A common type of expanded metal lath; used as a base for plaster.

diamond notch Same as V-notch.

diamond pattern On a roof, a pattern of tiles or shingles whose lower edges are V-shaped.

diamond slate An asbestos cement shingle or slate, approx. square in shape, with two corners nipped for use in diagonal slating.

diamond work See diaperwork.

diamond vault A ribless prismatic vault using thin concrete-slab construction.

diaper An allover pattern with motifs placed in a repeated design, esp. on a rectangular or diagonal grid.

diaper

diaperwork, diaper pattern A decorative masonry pattern formed by brick headers having a dark glazed finish exposed on one end; often laid in the flat unbroken surfaces of gable walls in repeated patterns of diamonds, crisscrossed lines, inverted V’s, or chevrons; also called black diapering.

diaperwork

diaphragm 1. A diaphragm plate. 2. A floor slab, metal wall panel, roof panel, or the like, having a sufficiently large in-plane shear stiffness and sufficient strength to transmit horizontal forces to resisting systems.

diaphragm action Descriptive of a floor system in which all columns that frame into the floor from above and below are maintained in the same position relative to each other.

diaphragm plate A relatively thin, usually rectangular plate, used to stiffen a metal-framed structure; provides additional strength and rigidity.

diaphragm pump A pump in which the piston is replaced by a clamped diaphragm that is set in vibration by a reciprocating rod, attached at its center.

diaphragm valve A valve whose action is controlled by fluid pressure on a diaphragm.

diastyle See intercolumniation.

diathyrum A vestibule in an ancient Grecian house with the street door at one end and the door to the courtyard at the other.

diatomite, diatomaceous earth, kieselguhr A white or light gray, chalky, natural siliceous material; obtained by mining deposits of fossil remains of small marine life; used as an extender in paints, as an aggregate in lightweight concrete, as a waterproofing material in portland cement, as a filter for water, and as an abrasive.

diatoni 1. In ancient Greek and Roman masonry construction, stones which extend the full thickness of the wall; same as through stones. 2. Quoins which project from a wall and have two dressed faces.

ancient construction with diatoni

diazoma The wide horizontal walkway between the lower and upper tiers of seats in a Greek theater.

diazoma, D

dichroic reflector lamp An incandescent lamp (usually a PAR lamp) with a built-in light filter which colors the light or removes a significant part of the infrared power from the light beam.

dictyotheton A type of masonry used by the ancient Greeks; composed of square-cut stones, forming a network or chessboard pattern; similar to the opus reticulatum of the Romans.

die 1. The middle portion of a pedestal between the base (or plinth) and the surbase; also called a dado. 2. A tool for cutting threads on pipe, screws, etc.

die, 1

dieback A condition often found in woody plant material where browning and death of the plant cells begin from the tip inward and may continue as far as the woody or perennial part of the plant.

die-cast Descriptive of a casting produced by forcing molten metal into a mold.

die cut Said of a member or device that has been punched from sheet material.

dielectric fitting In a water supply system, a special type of adapter (such as a union) used to connect a pipe containing copper with a pipe containing iron; used between dissimilar metals to prevent galvanic action from causing corrosion failure.

dielectric fitting

die line A longitudinal depression or protrusion formed on the surface of drawn or extruded material owing to imperfections on the die surface.

die-squared timber A timber having a square cross section, at least 4 in. (10 cm) on a side.

differential leveling The process of establishing the difference in elevation between any two points by using a level, 1 and a leveling rod.

differential settlement Relative movement of different parts of a structure caused by uneven sinking of the structure.

differential subsidence The difference in subsidence between two points on a structure.

diffuse illumination Lighting arranged so that an object is illuminated from a very large number of directions, rather than predominantly from a single direction.

diffuse light Light which is random in direction.

diffuse-porous wood A hardwood having pores of uniform size and distribution throughout each annual ring.

diffuser 1. Any device, object, or surface that scatters light (or sound) from a source. 2. For air-conditioning systems, see air diffuser.

diffuse reflection Reflection of light from a rough surface which scatters it in all directions.

diffuse reflection

diffuse sound Sound is said to be perfectly diffuse in a room when the sound waves travel in all directions with equal probability and the sound level of the reflected sound is everywhere equal.

diffusing glass Glass having an irregular surface to diffuse light; may be fabricated in flat sheets by rolling or pressing, or in hollow shapes by blowing.

diffusing panel A translucent material, such as that covering the lamps in a luminaire, used to distribute light over an extended area and to conceal the lamps and interior of the luminaire.

diffusing surface A reflecting surface which scatters incident light or sound in all directions.

diffusion lens A glass lens used to widen the distribution of light from a source so as to increase its diffusion.

diffusion streak On a clad sheet, a surface streak which results from the diffusion of alloying constituents into the coating from the core during thermal treatment.

dig-down pit Same as sunken pit.

digestion tank The first tank of a septic tank system in which organic material is processed.

digger A small excavator.

diglyph A member having two vertical channels or grooves, without the two lateral half grooves which characterize the triglyph.

dike, dyke 1. A dry stone wall. 2. A long low dam. 3. A bank of earth from an excavation. 4. An earth embankment which acts as a cofferdam for keeping water out of an excavation.

dilatancy The expansion of cohesionless soils when subject to shearing deformation.

diluent A thinner.

diluent air Air which is induced or admitted into a flue in order to dilute the products of combustion.

DIM. On drawings, abbr. for “dimension.”

dimension A geometric element in design, such as length, angle, or the magnitude of a quantity.

dimensionally stable Said of a building material whose dimensions remain relatively constant with changes in temperature and humidity.

dimensional stability The degree to which a material maintains its original dimensions when subjected to changes in temperature and humidity. See equilibrium moisture content.

dimension lumber, dimension stuff Lumber cut to a particular size and stocked for the building industry; usually 2 to 5 in. (5.1 to 12.7 cm) thick and 5 to 12 in. (12.7 to 30.5 cm) wide.

dimension ratio The average specified diameter of a pipe divided by the minimum specified wall thickness.

dimension shingles Shingles which are uniform, rather than random, in size.

dimension stock 1. Square-edged lumber usually of timber size; softwoods are at least 4 by 12 in. (10.2 to 30.5 cm), and hardwoods at least 4 ½ in. (11.5 cm) thick. 2. Timber from which dimension lumber is cut; maximum waste is left at the mill.

dimension stone Stone that is selected, trimmed, or cut to desired shapes and/or sizes for such uses as building stone, markers, paving blocks, flagging, or curbing.

dimension stone tile A dimension stone that is less than ¾ in. (20 mm) thick.

dimension stuff See dimension lumber.

dimension work Masonry constructed with dimension stone.

diminished arch, skeen arch, skene arch An arch having less rise or height than a semicircle.

diminished bar A glazing bar or muntin shaped so as to appear thinner in cross section than it actually is.

diminished column A column having a greater diameter at its base than at its capital.

diminished stile, diminishing stile, gun-stock stile A door stile having different widths above and below the middle rail, as in a glazed door in which the stile is narrower in the glazed portion.

diminishing courses On a roof: courses of tiles that diminish in height in going from the eaves to the ridge, thereby providing the appearance of greater height.

diminishing piece Same as diminishing pipe.

diminishing pipe, taper pipe A pipe of diminishing diameter which acts as a reducer.

diminishing rule A template used to establish the entasis of a column.

diminishing stile See diminished stile.

dimmer A device which varies the light intensity of a light source without appreciably affecting the spatial distribution of the light; usually an electric control device that varies the current flow and hence the light output of the lamp.

dimmer room A room in which are located the dimmers for controlling the lights for an auditorium or theater.

DIN Abbr. for “Deutsche Industrie Normal” (Germany Industry Standard).

dinette A recess off a living room, foyer, or kitchen that is used for dining purposes.

dinging A single, rough coat of stucco on a wall; often scored with a tool to form imitation masonry joints.

dingle An obsolete term for a temporary enclosure constructed at the entrance to a building as protection against the weather.

dining bay, dining recess Same as dinette.

dining room The principal room used for meals, in which the family in a private house, or guests in a hotel, come together at mealtimes.

Diocletian window See Venetian window.

diorama 1. A large painting, or a series of paintings, intended for exhibition to spectators in a darkened room in a manner to produce by optical illusions an appearance of reality. 2. A building in which such paintings are exhibited.

diorite Medium- to coarse-grained rock composed essentially of plagioclase feldspar and ferromagnesium minerals.

dip Of a trap, 1 the lowest portion of the inside top surface of the channel through the trap.

dip

dipcoat A paint or plastic coating which is applied by completely immersing an article in a tank of the coating; usually applied as a finishing or waterproof coating.

dip edge An edge on a metal flashing that is formed to promote the flow of water away from vertical surfaces.

diplinthius In ancient Roman construction, masonry which is two bricks thick.

dip solution Any chemical solution used to produce a specific color or finish on copper or copper alloys.

dipteral A classical temple having two rows of free columns, rather than a single row, surrounding the cella. Also see peripteral, pseudodipteral.

dipteral temple, shown in plan

dipylon 1. In ancient Greece, a gate consisting of two separate gates placed side by side. 2. (cap.) A gate of this type on the northwestern side of Athens.

direct-acting thermostat An instrument which activates a control circuit when a predetermined temperature is reached.

direct cold-water supply A series of water outlets fed directly from a water main.

direct cross-connection 1. A continuous cross-connection or interconnection such that the flow of water from one system to the other may occur under the slightest pressure differential between the two piping systems. 2. Any connection (such as a shutoff valve) between a potable water-supply line and a nonpotable source at which there is the possibility of contaminating the water supply should the valve (a) leak or (b) be opened when it should be closed.

direct cross-connection

direct current In an electric circuit, a current that flows in one direction only. Also see alternating current.

direct cylinder The tank of a direct-fired water heater.

direct dumping The discharging of concrete directly into place from a crane bucket or mixer.

direct expense All items of expense directly incurred by or attributable to a specific project, assignment, or task.

direct-fired air heater An air heater in which all the heat of combustion is discharged into the airstream; used in factories, warehouses, etc., to raise the temperature of air, which is brought in from the outside, to room temperature.

direct-fired water heater A water heater in which the source of heat (gas, oil, or electricity) is located at the water tank—in contrast to an indirect water heater.

direct glare Glare resulting from high brightness or insufficiently shielded light sources in the field of view or from reflecting areas of high brightness.

direct glazing Glazing that is set into a structure instead of into a frame mounted within a structural opening.

direct glue down See glue down.

direct heating Warming of a space by means of exposed heated surfaces (e.g., from a stove, fire, radiators, or pipes); both radiant heating and convection heating take place.

direct hot-water system A system in which water is heated in a central boiler and then distributed throughout a building; see the illustration under hot-water heating system.

direct-indirect lighting Lighting in which the luminaires are in the general diffuse category but emit little or no light at angles near a horizontal plane drawn through them.

directional lighting Lighting, predominantly from a preferred direction, which provides illumination on the work plane or on an object.

direct leveling The determination of differences of elevation by a continuous series of short horizontal lines; the vertical distances from these lines to adjacent ground marks are determined by direct observations on graduated rods with a leveling instrument equipped with a spirit level.

direct lighting Lighting in which luminaires distribute 90% to 100% of the emitted light in the direction of the surface to be illuminated, usually in a downward direction.

direct luminaire A luminaire which emits 90% to 100% of its total output below a horizontal plane through it.

direct nailing Same as face nailing.

direct-plunger elevator A hydraulic elevator which has a piston (plunger) directly attached to the elevator car frame.

Directoire style A transitional classicist style preceding the Empire style, named after the Directoire rule in France (1795–1799).

directory board An information board with changeable letters or symbols.

direct personnel expense Salaries and wages of principals and employees engaged on a project, assignment, or task, including mandatory and customary benefits.

direct return system A piping arrangement for a heating system (or air-conditioning or refrigeration system) in which the heating (or cooling) fluid, after it has passed through each heat exchanger, is returned to the boiler (or evaporator) by the shortest direct path.

direct selection The selection of a contractor by the owner, based on the owner’s evaluation of the contractor’s availability, competence, and reputation, as well as his or her fee.

direct solar water-heating system A solar water-heating system in which water passes directly from the potable water supply, through the collectors and storage, to the hot-water supply.

direct sound The sound which travels directly from the source to the point of observation—no reflection of sound is involved.

direct sound level The sound level of the direct sound in a room.

direct stress Stress without bending or shear; only compressive or tensile stress.

direct system A heating, air-conditioning, or refrigeration system in which heat is exchanged directly with a surrounding material or space.

direct water heater Same as direct-fired water heater.

dirt-and-stick chimney, dirt chimney Same as clay-and-sticks chimney.

dirt-depreciation factor See luminaire dirt-depreciation factor.

dirt resistance The ability of a paint coating (or the like) to resist soiling by foreign material deposited on, or embedded in, the dried coating.

disability According to the Americans with Disabilities Act, a legally specified incapacity or disqualification.

disability glare Glare that reduces visual performance and visibility and often is accompanied by discomfort.

disappearing stair, folding stair, loft ladder A swinging stair, usually a folding ladder, which enables passage to an attic space or loft. The stair is fixed to a trapdoor which, when closed, hides the stair from viewers below.

discharge coefficient See coefficient of discharge.

discharge head The energy per unit weight of fluid on the discharge side of a pump.

discharge lamp Any lamp that produces light by means of phosphors as a result of an electrical discharge through one or more gases or vapors within the lamp’s envelope (e.g., see fluorescent lamp).

discharge opening The opening at the base of a refuse chute through which the refuse drops into a refuse container or refuse compactor.

discharge pipe Any pipe that conveys the discharge from plumbing fixtures, appliances, or the like.

discharge valve A valve which regulates or closes off the flow of a fluid.

discharging arch, relieving arch, safety arch An arch, usually segmental and often a blind arch, built above the lintel of a door or window to discharge the weight of the wall above the lintel to each side.

discharging arch

discoloration Any change in color from the original color or from the desired color.

discomfort glare A low-level glare that causes discomfort and annoyance, but does not necessarily impair vision or visual performance.

disconnecting means A device (usually a circuit breaker, a fused switch, or a fused circuit-breaker-assembly) that disconnects the conductors of an electric circuit from the source of supply.

disconnecting trap Same as interceptor.

discontinuous construction Construction in which there is no solid connection between the rooms of a building and the building structure; or between one section of a building and another; esp. used to prevent the transmission of noise along a solid path.

discontinuous easement An easement requiring for its exercise an action by one party, as a right-of-way.

discontinuous impost A shafted impost, where the arch moldings are different from the moldings of the pier from which the arch springs.

discontinuous impost

disc tumbler lock Same as cylindrical lock.

dished hole A hole whose upper edge has been enlarged.

dishing The grading of the surface of the ground or pavement, usually to promote drainage.

disintegration Of concrete or the like, the deterioration into small fragments or particles.

disk sander A sanding machine or a power sander which has a circular abrasive (usually sandpaper) disk which rotates; used for smoothing or polishing surfaces.

dispersant An admixture which is capable of maintaining finely ground materials in suspension; used as a slurry thinner or grinding aid.

dispersing agent An addition or admixture capable of increasing the fluidity of pastes, mortars, or concrete.

dispersion 1. Any gas, liquid, or solid containing finely dispersed particles in suspension. 2. A paint containing finely dispersed particles of pigment or latex.

displacement pile A solid pile or hollow pile whose lower end is closed so that in being driven, the pile displaces an equivalent soil volume (either by compaction or soil displacement).

displuviatum An atrium, the roof of which was sloped outward from the compluvium instead of toward it.

disposal field Same as absorption field.

disposal unit See waste-disposal unit.

dissolved solids See solutes.

distance block A wood block which separates two components from each other at a fixed distance.

distance piece Same as setting piece.

distance separation For fire-protection requirements, the separation between an exterior wall of a building and an interior property line, or the center line of an adjacent street, or the exterior wall of another building; all measured at right angles to the exterior wall.

distegia Same as episkenion.

distemper A paint containing earth pigments, calcium carbonate, tinting colors, glue size, or casein, mixed with water; tempera.

distemper brush A wide flat paintbrush with long bristles; used in applying distempers, such as calcimine.

distillation A water purification process in which water is converted to a vapor by boiling it, and then reconverted to purified water by cooling the vapor.

the process of distillation

distributed load A load which acts evenly over a structural member or over a surface that supports the load.

distribution The movement of freshly mixed concrete toward the point of placement, either by motorized tools or by hand.

distribution-bar reinforcement, distribution steel In a reinforced concrete slab, small-diameter steel reinforcing bars, usually at right angles to the main reinforcement; intended to spread a concentrated load on the slab and to prevent cracking.

distribution board Same as distribution switchboard.

distribution box 1. In sanitary engineering, a box in which the flow of effluent from a septic tank is distributed equally into the drain tile lines that lead to the absorption field. 2. A junction box.

distribution box

distribution center A point in an electrical system in a building where secondary voltage (usually a low voltage) is distributed to different circuits within the building. Generally includes automatic overload protective devices that provide protection for the electric system in the event that the system is called upon to exceed its safe operating capacity; in that case, the system shuts down automatically.

distribution cutout In a primary circuit, an electrical cutout, 3 which disconnects the circuit as a means of overcurrent protection.

distribution line In sanitary engineering, a line of distribution tile.

distribution panel Same as panelboard.

distribution reinforcement See distribution-bar reinforcement.

distribution steel See distribution-bar reinforcement.

distribution switchboard An electric switchboard used to distribute power within a building; enclosed in a metal box which includes circuit breakers, fuses, and switches.

distribution tile In a sewage-disposal system, clay or concrete tile pipe, laid with open joints, which carries effluent from a distribution box.

distribution transformer A transformer that reduces the primary voltage to a secondary (lower) voltage for distribution within a building.

district surveyor A British term for building inspector.

distyle Having two columns in front; used in describing a classical building.

distyle, temple shown in plan

distyle in antis Having two columns in front between antae.

ditcher, ditching machine See trencher.

ditching machine

ditriglyph An interval between two columns such as to admit two triglyphs in the entablature instead of one, as usual.

ditriglyph

DIV On drawings, abbr. for division.

divan 1. In Muslim countries, a council room or hall for a court of justice. 2. A smoking room.

diversion valve Same as diverter.

diversity The nonsimultaneous occurrence of maximum demands on any given part of a system.

diversity factor 1. In an electric wiring system, the ratio of the sum of the individual maximum demands of the various subsystems to the maximum demand of the whole system. 2. In a gas piping system, the ratio of the maximum probable demand to the maximum possible demand.

diverter A valve (sometimes motorized) at a junction of a pipe tee; used to change the flow from one branch to another.

divided door Same as Dutch door.

divided light Glass in a window or glazed door that is divided into smaller panes by secondary framing members; see muntin.

divided tenon Same as double tenons, 1.

dividers A pair of compasses having both legs terminating in points; used for measuring, transferring, or comparing distances between two points when a precise measurement is required; also used to scribe an arc, radius, or circle, and to compare or transfer measurements directly from a rule.

divider strip A strip of metal embedded in terrazzo; used to serve as a control joint or as a decoration.

division One of the sixteen basic organizational subdivisions used in the AIA uniform system for construction specifications, data filing, and cost accounting. See illustration for contract documents.

division bar See muntin.

division wall See fire wall, 1.

diwan Same as divan, 1.

dkg Abbr. for “decking.”

DL 1. On drawings, abbr. for dead load. 2. On drawings, abbr. for deadlight.

D-line crack See D-crack.

DN On drawings, abbr. for “down.”

DO. On drawings, abbr. for “ditto.”

doat See dote.

dobying Same as mud-capping.

dock 1. A platform, usually the height of the floor or truck vans, which facilitates loading and unloading; a loading dock. 2. Short for scene dock.

dock bumper A resilient bumper attached to a loading dock, 1 to absorb truck impacts against it.

docked gable Same as jerkinhead roof.

document deposit See deposit for bidding documents.

dodecastyle Having twelve columns in the front row; said of buildings of classical type.

DOE Abbr. for the US Department of the Environment.

dog Same as dog iron.

dog anchor See dog iron.

dog bars Vertical rails in the lower portion of a gate.

dog-ear 1. An external corner made by folding a sheet of material without cutting it. 2. The corner of a sheet of material which is folded over. 3. Same as crossette. 4. The projections at the corners of a door or window casing.

dog-eared fold Same as dog-ear.

dogging device A mechanism which fastens the crossbar of a panic exit device in the fully depressed position.

dog iron, dog anchor A short bar of iron with its ends bent at right angles and pointed so as to hold together the two pieces into which they are driven.

dog iron

dogleg Said of a facility having one or more right-angled bends, as in a dogleg stair.

dogleg brick A special brick not having a rectangular shape; instead, the edge along the narrowest side is not a straight line but forms an obtuse angle. These bricks are especially used where the face of a wall forms an obtuse angle; this avoids the use of cut bricks and a mortar joint where the face of the wall changes direction; an angle brick.

dogleg chisel Same as corner chisel.

dog-leg pile A pile which has been bent or curved in driving.

dogleg stair, doglegged stair A half-turn stair which has no wellhole between successive flights; the rail and balusters of the upper and under flights fall in the same vertical plane.

dogleg stair

dog nail 1. A large nail having a head that projects considerably on one side. 2. A wrought nail used for fastening door hinges.

dog-run cabin Same as dogtrot cabin.

dog’s ear, dog ear Same as crossette.

dog shore A horizontal shore that is framed between vertical surfaces (without braces) such as between two buildings.

dog’s tooth Same as dogtooth.

dog’s-tooth course Same as dog-tooth course.

dog-tooth frieze A horizontal course of bricks, laid diagonally on edge in a masonry structure, which provides a decorative band in the form of a frieze.

dogtooth, tooth ornament 1. An ornament in medieval architecture and derivatives, of more or less elaborate motif, usually pyramidal with notched sides, the diagonal portions usually resembling petals or leaves which radiate from the raised point. 2. A brick laid with its corners projecting from the wall face.

dogtooth, 1

dog-tooth course A horizontal band of bricks, or course, that is laid diagonally on edge; each brick is set so that one corner projects from the face of the wall, often at an angle of 45 degrees; also called a dog’s-tooth course.

dog-tooth course on a brick chimney

dogtrot A breezeway.

dogtrot cabin A dwelling, often of log construction, consisting of two single-room cabins separated from each other by a covered open-air passageway (dogtrot); a common wood-shingled pitched roof typically covers both cabins, and each cabin has its own entrance and a chimney at its gable end. The dogtrot or breezeway not only serves to link the cabins, but also provides an outdoor sitting area. Also called a double-pen cabin.

dogtrot plan See possum-trot plan.

dollop A gob of bonding material, such as cement, applied in a specific area.

dolly 1. A block of hardwood placed on the upper end of a pile; acts as an extension piece and as a cushion during pile driving. 2. A tool for holding the head of a rivet and absorbing the impact while the other head is being driven. 3. A low cart or truck used for transporting heavy or bulky equipment.

Dolly Varden siding Beveled wood siding which is rabbeted along the bottom edge.

dolmen, table stone A prehistoric tomb of standing stones, usually capped with a large horizontal slab.

dolomite 1. A mineral form of calcium-magnesium carbonate; a constituent of some building limestones. 2. Limestone consisting principally of the mineral dolomite; dolostone.

dolomitic lime A trade term and misnomer for high-magnesium lime; the product does not contain dolomite.

dolomitic limestone Limestone that contains more than 10% but less than 80% of the mineral dolomite.

dolostone See dolomite, 2.

dome 1. A curved roof structure spanning an area; often spherical in shape. 2. A square prefabricated pan form; used in two-way joist (waffle) concrete floor construction. 3. A vault substantially hemispherical in shape, but sometimes slightly pointed or bulbous; a ceiling of similar form. Also see geodesic dome and saucer dome.

dome light A skylight having the shape of a shallow dome; often fabricated of glass or plastic; may be set into a roof to provide supplementary daylighting below it.

domestic hot-water heater Packaged equipment which heats water for domestic purposes.

Domestic Revival style A style of architecture in England in the 19th century loosely patterned after elements of the Queen Anne style, Domestic Revival, and aspects of the Picturesque Movement as well as the Arts and Crafts Movement; often characterized by timber-framed houses, ornate bargeboards, brickwork in diaper patterns, tall decorative chimney stacks, and leaded windows; a forerunner of the shingle style, in which tiles were used rather than wood shingles. Also called Old English style.

domestic sewage See sanitary sewage.

domical Pertaining to, resembling, or characterized by a dome, as a domical church.

domical vault See coved vault.

dominant estate Where a restriction on use of one piece of real property is imposed in order to confer a benefit upon the owner of another, the former is called the servient estate and the latter the dominant estate. For example, if ownership of one field confers upon its owner the easement or right to walk across the field of a neighbor in order to reach the highway, the field whose owner has that right is the dominant estate and that which may be crossed is the servient estate.

donjon Same as keep.

dook Same as furring strip.

door 1. An entranceway. 2. A barrier (usually solid) which swings, slides, tilts, or folds to close an opening in a wall or cabinet or the like. For additional definitions and illustrations of specific types, see automatic door, balanced door, battened door, blank door, blind door, board-and-battened door, car door, casement door, cellar door, Christian door, class-A door, class-B door, class-C door, class-D door, class-E door, crapaudine door, cross-and-bible door, divided door, double-acting door, double door, double-margin door, Dutch door, dwarf door, Egyptian door, elevator car door, false door, fire door, flap door, flush door, folding door, framed door, French door, half door, Holy door, jib door, landing door, ledged-and-braced door, ledged door, overhung door, Palladian door, paneled door, pocket door, revolving door, roll-up door, sash door, scuttle door, sham door, single-acting door, sliding door, storm door, swinging door, trapdoor, unframed door, vertical plank door, weather door, wicket, witch door, z-braced battened door, zambullo door.

door nomenclature

door band Same as door bar.

door bar A heavy bar across a door to prevent it from being opened, such as a plank dropped between metal holders on each side of the door-frame.

door bar

door bevel The bevel which is provided on the stile edge (lock edge) of a door so that the door may swing free of the doorframe; usually about 3° toward the doorstop, 1.

door bolt A manually operated sliding rod or bar attached to a door for locking it; a spring is not part of the locking mechanism.

door bolt

doorbrand 1. A bar used to fasten a door. 2. A strap hinge which holds in place the planks of a door.

door buck A wood or metal subframe, set in a wall, to which the finished frame is attached; also called a rough buck or sub-buck.

door bumper See doorstop, 2.

doorcap The wall area or decorative element directly above a doorway, often ornamented.

door casing, doorcase The finished frame surrounding a door; the visible frame.

door casing

door catch See catch.

door check Same as door closer, 1.

doorcheek A doorjamb.

door class See class-A door, class-B door, etc.

door clearance 1. The clearance between the bottom of a door and the finished floor. 2. Same as frame clearance. 3. The clearance between the meeting edges of a pair of doors.

door closer 1. A device combining a spring for closing and a compression chamber into which liquid or air escapes slowly, thus providing a means of controlling the speed of the closing action; also called a door check. 2. In elevators, a device or assembly of devices which closes an opened car or hoistway door by the use of gravity or springs.

door closer,1

door closer bracket A device which permits a door closer, 1 to be installed on the doorframe, rather than directly on the door.

door contact, door switch An electric contacting device for opening and closing a circuit, which is attached to a doorframe and operated by opening or closing the door.

doorframe An assembly built into a wall consisting of two upright members (jambs) and a head (lintel) over the doorway; encloses the doorway and provides support on which to hang the door.

doorframe

doorframe anchor An adjustable device, fabricated of metal, used to attach a doorframe to the surrounding structure; also see jamb anchor.

door furniture (Brit.) Any functional or decorative fitting for a door, excluding the lock and hinges. Same as door hardware.

door grille A grille in a prepared door opening which allows air to pass through but restricts vision and acts as a partial barrier.

door guide In a sliding door, a channel, 1 that keeps the door plumb while it moves.

door hand See hand.

door head 1. The uppermost member of a doorframe. 2. A horizontal projection above a door.

door head, England (15th cent.)

door head, doorjamb

door holder A device that holds a door open at selected positions.

doorhood A projecting covering over an external door to provide shelter from rain or snow.

doorhood

door jack A frame for holding a wood door in place while it is off its hinges and being planed.

doorjamb, doorcheek, doorpost The vertical member on each side of a door.

door knob The knob or handle that releases the latch on a door, permitting it to be opened.

door knocker A hinged knob, bar, or ring of metal, attached to the outside of an exterior door, to enable a person to announce his presence.

door knocker, England (15th cent.)

door landing A level floor surface immediately adjacent to a threshold of a doorway.

door latch See latch.

door leaf 1. A separately movable division of a folding or sliding door. 2. One of a pair of doors.

door light The glass area in a door.

door lining The finish of wood, metal, marble, etc., which surrounds the top and sides of a doorway.

door lock A device that prevents a door from being opened except with a key; for example, see box locks or case locks; also see lock.

door louver In a door, an opening with a series of slats, blades, or piercings which permit the passage of air.

door mullion The center vertical member of a double-door opening, set between two single active leaves; usually forms the strike side of each leaf; may be removable. Also see mullion.

doornail 1. A large-headed nail against which the knocker strikes. 2. A large-headed nail used to decorate or strengthen a door.

door opening, opening size The size of the doorframe opening measured from jamb to jamb and from floor line or threshold to head of frame; usually equal to the actual door size plus clearances.

door operator On elevators, a device or assembly of devices which opens and closes a car door and/or hoistway door by power other than by hand, gravity, springs, or the movement of the car.

door pivot See pivot, 2.

doorplate A plate on the exterior side of a door which gives the name of the occupant, apartment number, or the like.

door pocket The boxing or chamber in a wall which receives a sliding door when it is in the open position.

doorpost 1. See doorjamb. 2. A heavy post that frames one side of a doorway; in the past, doors were sometimes hinged directly to such a post instead of to a doorframe.

door rail A horizontal cross member which forms part of the framework of a door; connects the hinge stile to the lock stile, both at the top and bottom of the door and at intermediate locations; may be exposed, as in paneled doors, or concealed, as in flush doors.

door roller A hardware accessory, consisting of wheels on a track, which supports a sliding door.

door saddle Same as threshold, 1.

door schedule A tabulation, usually on a blueprint or in specifications, which lists all doors required on a job, indicating sizes, types, locations, and special requirements.

door screen A wire screen panel fixed in a door to exclude insects but permit the passage of air; may be removable to permit replacement by a glazed panel in cold weather.

door set An assembly of manufactured components of which a door is comprised, e.g., the door, door frame, door lining, etc.

doorsill The horizontal board or metal plate on the floor directly beneath a door; covers the joint where two types of floor materials meet; also called a saddle.

doorstead A doorway, including all components of the door and doorframe.

doorstep A step at a door; often one of several at the exterior of an outer door.

door stile A vertical structural member of the door itself; this is in contrast to a vertical structural member of the doorframe, which is called a jamb. The inner stile (i.e., the stile nearest the axis about which the door swings) is called the hinge stile; the outer stile is called the lock stile.

doorstone The stepstone at the threshold of a door.

doorstop 1. A strip against which a door shuts in its frame. 2. A device placed on a wall behind a door, or mounted on the floor, to prevent opening the door too wide; also called a door bumper.

door strip A strip attached to the bottom edge of a door to cover the gap between the bottom edge and the doorsill.

door surround A decorative element or structure around a doorway; for example, see Gibbs surround.

door sweep See sweep strip.

door swing See hand.

door switch See door contact.

door threshold Same as threshold, 1.

door track A metal track or rail on which a sliding door moves.

door transom A transom, 2.

door tree The jamb or sidepiece of a door.

door trim The casing or moldings used around a doorframe to conceal the crack or joint between the frame and wall or for decorative effects.

door unit 1. A door and frame assembly. 2. As specified in building codes: the clear opening of each door in a required fire exit.

doorway An opening in a wall, with a door, which provides a passageway into a room or building.

door window A French door.

dope 1. A material added to a building material such as mortar or plaster to retard or accelerate the set. 2. A material added to a batch of paint to adjust it to specifications. 3. A solution of cellulose nitrate applied to a porous fabric as a protective coating. 4. A compound used in making a pipe joint, as a lubricant and to ensure a leakproof joint.

Doric capital The topmost member of a column or pilaster of the Doric order.

Doric cyma A cyma recta.

Doric order In Classical architecture and derivatives, the column and entablature developed by the Dorian Greeks. Characterized by sturdy proportions, a simple capital, a frieze usually having regularly spaced triglyphs and metopes, and mutules in the cornice; plainer than the Corinthian order or the Ionic order (although the Tuscan order later introduced by the Romans was even plainer). The Roman Doric column has a base but is usually not fluted (see illustration of base, which follows); in contrast, the Greek Doric column is usually fluted but has no base. Compare with Tuscan order.

Doric order: a, Greek; b, Roman

dormant, dormant tree In a timber-framed house, a large horizontal beam that supports beams of a lesser size.

dormant window Same as dormer.

dormer, dormer window A structure projecting above a sloping roof, usually housing a vertical window. It is not part of the roof structure but is framed separately, and often provides daylight and ventilation for a room located in a garret or loft space. For definitions and illustrations of specific types, see arched dormer, deck dormer, eyebrow dormer, flat-head dormer, gable dormer, hipped dormer, inset dormer, mission dormer, oval dormer, Palladian dormer, pedimented dormer, pitched-roof dormer, pointed dormer, polygonal dormer, recessed dormer, ridge dormer, round dormer, segmental dormer, shed dormer, through-the-cornice dormer, triangular dormer, wall dormer, watershed dormer.

dormer cheek The vertical side of a dormer.

dormer window, dormer A vertical window which projects from a sloping roof, placed in a small gable.

dormer window

dormitory A place, building, or room to sleep in.

dormitory suburb See satellite community.

dorsal Same as canopy.

dorsel 1. A canopy. 2. Same as reredos.

dorter, dortour A dormitory, esp. in a monastery.

dosing tank In sanitary engineering, a collection tank for sewage which is subsequently discharged for further processing.

dossal Same as reredos.

dossel 1. Same as reredos. 2. A hanging of silk, satin, damask, or cloth of gold at the back of an altar of a church and sometimes also on the sides of the chancel.

dosseret A member or supplementary capital resting on the top of the capital of a column; see impost block; also called a double capital.

dot A small spot of plaster placed on a plastering surface, or a temporary nail; to assist the plasterer in leveling a wall and in obtaining proper plaster thickness.

dote, doat, doze A form of decay in which wood becomes soft and weak and has a dull lifeless appearance.

doty Said of timber which has decayed.

double-acting butt Same as double-acting hinge.

double-acting door A door that swings in both directions; see swinging door.

double-acting frame A doorframe which does not contain doorstops, thereby permitting installation of a double-acting door.

double-acting hinge A hinge which permits motion in either of two directions; used on swinging doors.

double-acting pump A reciprocal pump in which the reciprocating motion of a piston does work in both directions.

double angle Two L-shaped metal structural members which are fastened together, back to back.

double architrave An architrave, 1 having two decorative bands around an opening (such as a door or window in a wall of a building); usually the bands are in different planes, separated by an ornamental molding.

double ax An ax having a two-edged blade.

double back See double up.

double bead Two beads, side by side; there is no other surface or molding between them.

double-bellied Descriptive of a baluster whose profile is the same at both its upper and lower ends.

double-bellied baluster A baluster whose upper half has the same profile as the lower half.

double-bend fitting In plumbing, an S-shaped pipe fitting.

double-beveled edge The edge of a door (along the lock stile) which is beveled from the center of the edge toward each door face.

double-break switch In electric wiring, a switch which opens a conductor at two points.

double bridging Bridging which is placed between adjacent joists at positions which divide the joists into three lengths.

double capital Same as dosseret.

double-center theodolite Same as repeating theodolite.

double chimney 1. A pair of exterior chimneys, of approximately the same size, one on each side of a gable end of a house. 2. The chimneys for two fireplaces that open back to back, serving two different rooms; commonly has two flues.

double church A church constructed in two stories, affording two places of worship, one above the other; a large hole in the floor of the upper church enables the two congregations to hear the same service.

double-cleat ladder Similar to a single-cleat ladder, but wider, with an additional center rail which allows for two-way traffic of workmen ascending and descending.

double cloister An ambulatory that is divided in two by a series of columns or piers.

double-cone molding A molding enriched with carved cones joined base to base and apex to apex.

double corner block, pier block, pilaster block A concrete masonry unit having solid rectangular end faces as well as solid rectangular side faces.

double corner block

double course, doubling course A double layer of shingles or the like, one over the other, providing a minimum coverage of two thicknesses.

double course

double-crib barn See crib barn.

double cross-vault See cross vault.

double-cut file A file having two sets of cutting ridges, each set crossing the other; the ridges are diagonal with respect to the center line of the file.

double-cut saw A saw whose teeth have been cut so that the blade cuts on both the pull and the push strokes.

double decker A two-story house that provides living quarters for two families; it has one apartment on each floor and a separate entrance for each family.

double-decker barn A barn having three levels (including a loft) that is built into a hillside having a steep slope.

double-decker porch See two-tiered porch.

double dome A pair of domes, one set within the other, both of which have the same center of curvature.

double door Two single doors (leaves) hung in the same doorframe.

double-door bolt Same as cremone bolt.

double-dovetail key, hammerhead key A key made of hardwood which is used to join two timbers; has a dovetail on each end which is driven into a corresponding recess in each timber.

double eaves course Same as double course.

double egress frame A doorframe which is prepared to receive two single-acting doors swinging in opposite directions, both doors being of the same hand.

double door with fanlight above

double-ended substation A electric substation consisting of two switchboards in one common assembly, separated physically and electrically by a “tie circuit breaker.”

double ender A medieval church having an apse at both the east end and the west end.

double-end-trimmed Descriptive of lumber which is sawn reasonably square on both ends.

double-entry stair Same as double stair.

double-extra-strong pipe A standard designation for steel pipe in which the thickness of the pipe wall has been increased beyond that of standard-weight pipe to provide double strength.

double-faced 1. Descriptive of any joinery, as a molding, which is formed of two parts having faces in different planes. 2. Any material which is finished on both sides.

double-faced hammer A hammer with a striking face at each end of the head.

double-faced ware, porcelain enamel ware Ware that has a finish coat on both surfaces.

double feathering The subdivision of large cusps into smaller ones.

double Flemish bond A brickwork pattern showing a Flemish bond on both faces of a wall.

double floor, double-joisted floor, framed floor A floor in which the binding joists support the common joists above and the ceiling below.

double format pavior A brick or tile made esp. for paving and having double the bed face, or double the longer face perpendicular to the bed face.

double-framed floor A double floor in which the binding joists are framed by girders.

double-framed roof A roof in which longitudinal members (such as a ridge beam and purlins) are used.

double framing Using twice the usual number of framing members to provide additional strength.

double-fronted lot A lot bounded by a street on the front and back.

double-gable roof An M-roof.

double glazing Two panes of glass, usually parallel, with an air space between; used to provide increased thermal and/or sound insulation.

double glue-down See glue down.

doublehanded saw A saw operated by two men, one at each end.

double-headed nail, scaffold nail, form nail A nail having two heads, one above the other; the upper head is driven with a hammer, and it is used to withdraw the nail; the lower head bears on the surface into which the nail is driven; used on temporary structures such as scaffolds, formwork, etc.

double-headed nail

double header A header joist made of two pieces of lumber, fixed together by bolts or nails, to provide greater strength than a single piece.

double header

double-hipped roof A hipped roof having a double slope; also see bonnet roof.

double house 1. A pair of semi-detached houses having a plan that is symmetric on both sides of the common wall; each of the two units has its own entry. 2. See Cape Cod house. 3. See Charleston house.

double-hung window, double-hung sash window A window having two vertically sliding sashes, each closing a different part of the window; the weight of each sash is counterbalanced for ease of opening and closing.

double-hung window: terminology

double-intersection truss A truss, each panel of which has two intersecting diagonals.

double jack rafter A short rafter that joins a hip to a valley.

double-joisted floor See double floor.

double junction A fitting for a water pipe or a drainage pipe which has a branch on each side.

double lancet window A window having a mullion which is so shaped as to form two lancets.

double lath Wood lath, twice the normal thickness.

double lean-to roof A V-shaped roof formed by two lean-to roofs meeting at their low edge with a gutter at their intersection.

double-lock seam A type of seam between the edges of adjacent metal sheets; formed by making a double fold, then dressing down to form a seam.

double-lock seam

double-lock welt Same as double-lock seam.

double L stair A platform stair with two intermediate landings, one near the top and one near the bottom, with a 90° change of direction at each landing.

double-margin door A door having the appearance of a double door.

double measure In joinery, work which has molding on both sides.

double meeting rail A horizontal fixed meeting rail where two adjacent pivoted sashes (ventilators, 2) meet.

double meeting stile The vertical equivalent of a double meeting rail.

double-molded Said of doors that are molded on both sides of the framing.

double monastery A monastery and a nunnery adjacent to each other, sharing the same church and under the rule of the same superior.

double offset In plumbing, two changes of direction which are in succession in a continuous pipe.

double partition A partition built with separated framing members for each face so as to form a cavity space in the center for purposes of sound insulation or to conceal sliding doors.

double-pen cabin A log cabin having two adjacent rooms under a common roof; usually has a chimney at each end of the cabin; often a porch across the full width of the cabin. Also see center-hall cabin, dogtrot cabin, saddlebag cabin.

double piled Said of a house that has two parallel rows of rooms which are separated by a corridor

double-pile house A house that is two rooms deep. Also see pile, 2 and single-pile house.

double-pitched Having a pitch in two directions, as a gambrel roof.

double-pitched roof A roof having two flat slopes on each side of a central ridge; for example, see gambrel roof.

double-pitched skylight A skylight which has two slopes and straddles the ridge of a roof.

double-pole scaffold A scaffold supported from the base by a double row of uprights, independent of support from the walls and constructed of uprights, ledgers, horizontal platform bearers, and diagonal bracing.

double-pole switch In electric wiring, a switch which has two blades (and associated contacts) for opening or closing both sides of a circuit simultaneously.

double porch A two-tiered porch in which the porches on the first and second stories appear to be virtually identical in design.

double pour In built-up roofing, two separate applications of a top coating of bitumen and surfacing; esp. used on level roofs designed to hold water.

double-quirked bead See quirk bead, 2.

double-rabbeted frame A doorframe having recesses along both sides so that a door can be hung on either side of the frame.

double raised panel See raised panel.

double-rebated frame Same as double-rabbeted frame.

double return stair, side flights A stair having one flight from the main floor to an intermediate landing and two side flights from that landing to the floor above.

double return stair

double Roman tile A Roman tile having an additional roll up the center of the tile that matches (and is parallel to) the roll at its edges.

double roof A timber framing system in which the common rafters rest on purlins which provide intermediate support.

double-run stairs Two separate flights that start and finish at the same levels, and cross each other about the center point of each stair.

double-saddle notch At a corner of a log cabin, one of a pair of rounded notches cut on opposite sides of a horizontal log near one end; it forms a joint at the corner with a round unnotched log set at a right angle between such a pair of notched logs. Sometimes simply called a saddle notch; also see notch.

double shear The shear to which a member is subject when the shearing stress is along two section planes.

double-shell tile Ceramic tile with double faces separated by short webs.

double-shouldered chimney Same as stepped-back chimney.

double sliding door A pair of sliding doors which can pass each other, each in its own track.

double skirting A baseboard that is much higher than usual.

double square See adjustable square.

double stair An open stair having a pair of staircases leading down from a landing; usually designed to be impressive; compare with double-return stair.

double step A double notch cut into a tie beam which supports a rafter in a timber framing system.

double-strength glass Sheet glass having a thickness of between 0.118 in. (3.00 mm) and 0.113 in. (3.38 mm).

double-suction pump A pump having a spiral-shaped casing in which the water enters the impeller from both sides of the impeller so that hydraulic unbalance is practically eliminated.

double-sunk Recessed or lowered in two steps, as when a panel is sunk below the surface of a larger panel.

double surface treatment Two successive treatments applied to a surface, such as asphaltic material followed by a mineral aggregate.

double-swing door Same as double-acting door.

double-swing frame A doorframe which is prepared to receive a pair of single-acting doors, both of which swing in the same direction.

double T-beam A precast concrete member composed of two beams with a common slab across the top.

double tenons 1. Two tenons, side by side, at one end of a member; also called a divided tenon. 2. Two tenons, one at each end of a member, which are coaxial.

double tenons, 1: a, b

double-throw bolt A door bolt that can be projected beyond its first position, into a second (or fully extended) position to provide additional security.

double-throw switch In electric wiring, a switch which can charge the circuit connections by moving the switch blade from one of two sets of contact clips into the other.

double-tiered porch Same as two-tiered porch.

double-tier partition A partition which extends two stories in height.

double up, double back A method of applying plaster; first the plaster base coat is applied; then this is covered with plaster from the same mix before the base coat has set. A form of two-coat work.

double vault A vault, usually domical, consisting of an inner shell separated from a higher outer shell.

double vault

double wall A masonry wall composed of two walls with a space between them; the space may be filled with a material such as fiberglass to provide additional thermal insulation and sound insulation.

double-wall cofferdam A cofferdam formed by a double wall of sheeting (such as interlocking steel sections) and backfilled with soil or crushed stone.

double waste and vent Same as dual vent.

double-welded joint In arc welding and in gas welding, any joint welded on both sides.

double welt Same as double-lock seam.

double window 1. Two windows, one outside the other, as a storm window, used to provide improved thermal and noise insulation. 2. A window which is double glazed, with an air space between. 3. Two windows, side by side, which form a single architectural unit.

double wrench A wrench having a set of jaws at each end.

double-wythe wall See double wall.

doubling course See double course.

doubling piece 1. A cant strip. 2. A tilting fillet. 3. See arris fillet.

doubly prestressed concrete Concrete which is prestressed in two directions that are mutually perpendicular.

doubly reinforced concrete Concrete having both compression reinforcement and tension reinforcement.

doucine A cyma molding.

doughnut See concrete collar.

Douglas fir, Oregon pine, red fir, yellow fir A strong, medium-density, medium- to coarse-textured softwood; widely used for plywood and as lumber and timber in construction work.

dovecote A structure that houses doves or pigeons; often square, hexagonal, octagonal, or round in plan and one-and-a-half or two stories high; typically topped with a finial; once popular because the birds provided a tasty source of fresh meat. The interior is honeycombed with niches in which the birds may rest. Also called a pigeon house or pigeonnier.

dovetail 1. A splayed tenon, shaped like a dove’s tail, broader at its end than at its base. 2. A joint formed by such a tenon which is fitted into the recess of a corresponding mortise.

dovecote

dovetail,1

dovetail,2

dovetail anchor slot A slot which is nailed to a concrete form (the open end is against the wood); the ends of the slot are temporarily closed with a piece of wood or cellular foam. After the concrete is poured and the forms removed, the slot is used for anchoring masonry to the concrete.

dovetail baluster A baluster having a dovetail base for attachment to the stair tread.

dovetail brick A brick which has one end formed like a wedge; the other end has a recess to receive the wedge-like end of another brick.

dovetail cramp A dovetail-shaped cramp for lifting masonry.

dovetail cutter A rotary cutting tool, used to shape dovetails.

dovetail feather joint A double-dovetail key.

dovetail half-lap joint, dovetail halved joint, dovetail halving joint A joint formed by two members of equal thickness in which a dovetail, 1 at the end of one member is fitted into a corresponding mortise in the second member; half the thickness of each is removed.

dovetail half-lap joint

dovetail hinge Same as butterfly hinge.

dovetail joint Same as dovetail, 2.

dovetail lath, dovetail sheeting A type of metal lath, now called rib lath.

dovetail margin Any band or strip which is dovetailed.

dovetail miter Same as secret dovetail.

dovetail molding, triangular fret molding A molding decorated with fretwork in the form of dovetails.

dovetail notch At a corner of a log house, a notch in the shape of a dovetail at the end of a rectangular exterior timber; forms a strong, interlocking rigid joint when mated with an appropriately notched hewn timber at right angles to it. Compare with half-dovetail notch.

dovetail plane A plane used for cutting tongues and grooves for dovetail joints.

dovetail saw A small tenon saw having a very thin blade and fine teeth.

dovetail saw

dovetail sheeting See dovetail lath.

dowel A cylindrical wood or metal rod; used to secure two pieces of wood, stone, concrete, etc., by inserting it in a hole through the two members.

dowel-bar reinforcement Short reinforcing bars of steel which extend approximately equally into two abutting pieces of concrete, to increase the strength of the joint.

dowel bit, spoon bit A boring tool, the barrel of which is a half cylinder terminating in a conoidal cutting edge or radial point; used with a brace.

dowel joint Any carpentry joint making use of dowels.

dowel joint

dowel lubricant A lubricant applied to steel reinforcing bars in expansion joints to reduce bond with the concrete, so as to promote unrestrained longitudinal movement.

dowel pin 1. A dowel. 2. A metal pin having a sharpened or deformed end used to fasten mortise-and-tenon joints.

dowel plate A hardened steel plate containing holes of various diameters; used to cut dowels by driving pegs through the holes to remove excess wood.

dowel screw A dowel having threads on both ends.

downbrace A timber member between a corner post and a doorsill.

downcomer 1. A downspout. 2. Any pipe in which the flow is substantially vertical.

down conductor The vertical portion of an electric conductor used in a lightning protection system to provide a lightning current path from the air terminals to ground.

downdraft, Brit. downdraught 1. A downward current of air in a chimney or flue, often carrying smoke with it. 2. A downward current of air resulting from the passage of air across a window surface, which cools it and increases its density so that it moves downward.

down-feed system 1. A piping arrangement for a heating (or air-conditioning or refrigeration) system, in which the heating (or cooling) fluid is circulated through supply mains that are above the levels of the heating (or cooling) units they serve. 2. A water distribution system in which the water distribution main is located at the top of the pressure zone; the distribution-main supplies the risers that distributes water downward to the lowest point of the zone.

down lead Same as down conductor.

downlight A small direct luminaire (recessed, surface-mounted, or suspended) whose light is directed vertically downward.

downlight

downpipe See downspout.

downpipe shoe The fitting at the base of a downspout that changes the direction of the flow of water, discharging it horizontally, clear of the wall.

downspout, conductor, downcomer, downpipe, leader, rain leader, rainwater pipe A vertical pipe, often of sheet metal, used to conduct water from a roof drain or gutter to the ground or cistern.

downspout

downstage The front part of a stage, nearest the audience.

downstairs The lower floor or floors of a dwelling.

downzoning The change in the zoning classification of a property from a zoning classification of higher use to one that is lower; for example, from commercial use to residential use.

DOZ On drawings, abbr. for “dozen.”

doze See dote.

dozer Same as bulldozer.

dozer shovel A bulldozer having a front-mounted bucket used for digging, loading, or pushing.

dozy See doty.

DP On drawings, abbr. for dew point.

dpc Abbr. for dampproof course.

d.p.c. brick A brick having an average water absorption not greater than 4.5% by weight.

dpm Abbr. for “dampproof membrane.”

DR 1. On drawings, abbr. for drain. 2. Abbr. for dressing room. 3. Abbr. for dining room.

draft, Brit. draught 1. A current of air or gases, as an air current which flows through a flue, chimney, or heater; or a localized air current which results in more heat being withdrawn from a person’s skin than is normally dissipated. 2. A narrow, dressed border around the face of a stone, usually about the width of a chisel edge; also called a drafted margin or margin draft.

draft bead, deep bead, sill bead, ventilating bead, window bead A small fillet or strip which is fixed to the sill of a double-hung window; permits ventilation at the meeting rail while avoiding a draft at the sill; also called a draft stop.

draft chisel Same as drafting chisel.

draft curtain See curtain board.

drafted margin See draft. 2.

drafted masonry Masonry having a draft, 2 around the face of the stone.

draft fillet In glazing where putty is not used, a fillet on which the glass rests.

draft hood 1. A device fitted into or on top of a flue to prevent downdrafts. 2. An open enclosure over a gas-fired furnace. Serves to create a stack effect which more readily mixes the exhaust gases with air and directs the mixture to the chimney; prevents back drafts from getting into the furnace.

drafting chisel A chisel esp. used for cutting a border or line at the edge of a stone.

drafting machine A device, used in drafting, that provides the combined functions of a T-square, scale, triangle, and protractor; it is attached to a drawing board or drawing table.

drafting machine

drafting pen A pen especially designed for use in mechanical drawing. See drawing pen.

drafting pen

draft regulator A device that maintains a desired draft in a gas appliance by automatically reducing the draft to the selected value.

draft stop A building material installed to prevent the movement of air, smoke, gases, and flame to other areas of the building through a large concealed passage, such as a suspended ceiling.

drag 1. A piece of sheet steel with a toothed edge along the long dimension; used to level and scratch plaster to produce a key for the next coat; a comb. 2. A tool consisting of a steel plate having a finely serrated edge; used to dress stone by dragging it back and forth across the surface.

dragged Said of an exposed surface over which a drag or comb has been pulled or worked to produce a textured surface.

dragging beam Same as dragon beam.

dragging piece Same as dragon beam.

dragline A bucket attachment for a crane; used for removing earth by pulling the bucket toward the crane.

dragline

dragon beam, dragon piece A short, horizontal piece of timber which bisects the angle formed by the wall plate at the corner of a wood-frame building; one end serves to receive and support the foot of a hip rafter; the other end is supported by a dragon tie.

dragon’s blood A naturally occurring deep red resin; used as a tinting material, principally in varnishes.

dragon piece See dragon beam.

dragon post A post at the corner of a house that has a jetty at the front as well as a jetty on a side of the house.

Dragon style A mode of architecture, popular in 19th-century Scandinavia, that exhibited seagoing motifs, such as dragon figureheads; based on traditional log construction and said to be reflective of pride in the Viking Age.

dragon summer A dragon beam of unusually large size.

dragon tie An angle brace which supports one end of a dragon beam.

drag shovel Same as backhoe.

drag strut A structural member used to transfer a lateral load across a building to some part of the vertical structural system.

drain 1. Any pipe in a building-drainage system which carries waste water or water-borne waste. 2. Any pipe or channel for carrying waste water or storm water.

drainage 1. A drainage system, either artificial or natural. 2. The water that is drained off. 3. The removal, by natural or artificial means, of surface water or groundwater.

drainage area An area having a drainage channel beneath the surface.

drainage basin The area within which all surface water flows toward the lowest point of its elevation.

drainage channel A channel for conveying storm-water runoff; usually lined with concrete, grass, riprap, or the like, to reduce erosion of the channel.

drainage classification A system of drainage classification devised by the Soil Conservation Service of the US Department of Agriculture. The most porous soil in this classification system is said to be excessively drained, in which water is removed from the soil very rapidly. In contrast, is the least porous soil, classified as very poorly drained, in which water is removed from the soil so slowly that the water table remains at or near the surface most of the time.

drainage envelope The materials which completely surround a pipe, providing support and/or protection.

drainage fill 1. Lightweight concrete which is placed on roofs or floors to promote drainage. 2. A base course of granular material placed between a sub-grade and floor slab to retard the capillary rise of moisture.

drainage fitting, Durham fitting A cast-iron, threaded fitting, used on drainage pipes; has a shoulder such as to present a smooth, continuous interior surface.

drainage fixture unit Same as fixture unit.

drainage fitting

drainage hole An opening in a construction which permits unwanted water to drain away, e.g., from behind a retaining wall.

drainage piping All or any part of the drainpipe of a plumbing system.

drainage system The piping network within a structure which conveys sewage, rainwater, or other wastes from their point of origin to a point of disposal, such as a public sewer or a private treatment facility.

drainage tile Same as drain tile.

drainboard, Brit. draining board A work surface, adjacent to a sink, having a built-in pitch so that it drains into the sink.

drain cock A small cock or faucet, at the lowest point in a tank, for draining off the liquid.

drain field Same as absorption field.

drainpipe 1. Any pipe that serves as a drain. 2. Same as downspout.

drain spout Same as downspout.

drain test A water test or an air test of a drainage or vent system for leakage.

drain tile A hollow tile, usually laid end to end as piping (with open joints) in soil in order to drain water-saturated soil, or used to permit fluid in the hollow-tile pipe to disperse into the ground (as in an absorption field).

drain trap Same as trap, 1.

draped tenon Same as deflected tenon.

drapery panel 1. See linenfold. 2. One unit of drapery.

drapery track Same as curtain track.

draught Same as draft.

draught excluder A British term for door strip.

draught stop Same as fire stop.

draw bar A bar that can be slid through a socket attached to the face of a door into another socket attached to the door jamb, thus securing the door in a closed position.

drawbolt Same as barrel bolt.

drawbore A hole in the tenon of a mortise-and-tenon joint which is not in line with the holes of the mortise; when a pin is driven through, the joint becomes tighter.

drawbridge At the entrance of fortifications, a bridge over the moat or ditch, hinged and provided with a raising and lowering mechanism so as to hinder or permit passage.

drawbridge

draw cock See pet cock.

draw curtain A theater curtain that moves horizontally, usually divided in the middle so that each half can be pulled to one side of the stage.

drawdown The distance by which the ground-water level is lowered as a result of pumping.

drawer dovetail See lapped dovetail.

drawer kicker A wood piece which prevents a drawer from tilting downward when it is pulled out.

drawer roller A device used to ease the sliding of a drawer open or shut, usually by means of a metal or fiber wheel rotating on a metal frame.

drawer runner, drawer slip In drawer framing, one of a pair of strips on which the drawer slides.

drawer slide A mechanism employing guides and rollers that support a drawer and permit its easy operation.

drawer stop A block which stops the inward movement of a drawer when it has reached its proper position.

drawing room A formal reception room, usually in a prominent location of a large home, mansion, or manor house.

drawings The portion of the contract documents showing in graphic or pictorial form the design, location, and dimensions of the elements of a project; usually include plans, elevations, details, and schedules, as well as graphical and pictorial portions of the contract documents.

draw-in box Same as pull box.

draw-in system In electric wiring, a system using conductors installed in conduits, ducts, raceways, and boxes, thereby permitting removal and replacement of any conductor without disturbing any part of the building structure or finish.

draw-off tap See bibcock.

drawknife, drawshave A woodworking tool consisting of a blade with a handle at each end; the tool is drawn over the surface toward the user.

drawknife

drawn finish A smooth, bright finish on metal tubing, wire, rod, bar, and strip; obtained by drawing the metal through a die.

drawn glass, flat-drawn glass, flat-drawn sheet glass Sheet glass fabricated by the continuous drawing of the molten glass from a furnace; has fire-finished surfaces, not perfectly flat and parallel, resulting in some distortion.

drawn product A product formed by pulling material through one or more dies.

drawn wire Wire brought to final dimensions by being drawn through one or more dies.

drawshave A drawknife.

dredge 1. A floating excavator for removing earth or rock from under water. Usually accomplished by clamshell, power shovel, or cutterhead combined with a suction line. 2. To remove soil from an area under water.

drencher system A fire-protection sprinkler system which provides a water spray to protect the exterior of a building against fire; see deluge sprinkler system.

dress circle In an opera house, theater, or the like, a tier of seats above the main seating area—usually the first or lowest.

dressed Descriptive of brick, lumber, or stone which has been prepared, shaped, or finished by cutting, planing, rubbing, or sanding one or more of its faces.

dressed all around Said of a timber that has been planed smooth on all four sides.

dressed and matched boards, D and M boards, dressed and matched lumber, planed matchboards, tongue-and-groove boards Boards or lumber that has been planed smooth; cut so that a tongue along one edge fits into a groove cut along the edge of the adjacent piece.

dressed and matched boards

dressed dimension See dressed size.

dressed lumber, dressed stuff, surfaced lumber Lumber having one or more of its faces planed smooth.

dressed size The dimensions of a timber after sawing and planing; usually about in. (0.95 cm) in thickness or ½ in. (1.27 cm) in width less than the nominal size.

dressed stone Stone that has been worked to desired shape; the faces to be exposed are smooth; usually ready for installation.

dressed stuff See dressed lumber.

dressed timber See dressed lumber.

dresser A plumber’s tool used to flatten sheet lead and straighten lead pipe.

dresser coupling A clamp-style coupling for unthreaded pipe.

dresser joint A type of Normandy joint.

dressing, dressings 1. Projecting ornamental moldings and carved decorations of all kinds. 2. Masonry or molding of better quality than the facing brick; used around openings or at corners of buildings; often made of gauged brick. 3. Smoothing a stone surface. 4. Bossing.

dressing compound, bonding compound A hot- or cold-applied bituminous liquid used to coat exposed surfaces of roofing felt.

dressing room A room used for changing costumes and applying makeup in a theater, opera house, and the like.

dress plate Same as cover plate.

DRG On drawings, abbr. for “drawing.”

drier 1. An additive which is mixed with paints and varnishes to speed their drying by absorbing oxygen from the air. 2. See soluble drier. 3. A device containing a desiccant, placed in a refrigerant circuit; used to collect and hold within the desiccant all water in the system in excess of the amount which can be tolerated in the circulating refrigerant.

drier scum See scum.

drier white Superficial discoloration of clay-ware during drying; usually caused by adherence of soluble salts to the surface of the ware.

drift 1. The lateral deflection of a building, due to wind or other loads. 2. In a water spray device, the entrained unevaporated water carried from the device by air movement through it. 3. See driftpin, 2. 4. A deposit of loose materials such as gravel, rock fragments, clay and other soils which have been driven together by water, wind, or ice.

driftbolt 1. A short rod or square bar driven into holes bored in timber, for attaching adjacent sticks to each other or to piles; varies from 1 to 2 ft (0.3 to 0.6 m) in length; often provided with a head or with a sharpened end; also called a drift, or driftpin. 2. A steel bolt used to drive out other bolts.

drifter A type of pneumatic, percussive rock drill.

drift index 1. The ratio of the lateral deflection of a building to its height. 2. The ratio of the lateral deflection of a story of a building to the height per story.

drift limitation See drift index.

driftpin 1. A square or round metal rod with no threads, driven into an undersized, pre-bored hole as a substitute for a bolt, screw, or other fastener. 2. A short, tapered rod for enlarging rivet holes or bringing them into line; also called a drift. 3. A driftbolt. 4. A tapered round rod used to align holes in two or more pieces of metal.

driftpin

drift plug 1. A hardwood cylindrical plug which is driven through a soft-metal pipe to straighten it. 2. A conical plug driven into one end of a soft-metal pipe to produce a flare.

drift punch A punch with long taper and blunt end for aligning holes.

drift punch

drill 1. A hand- or motor-driven rotary tool used with a bit for boring holes in a material. 2. A hand-held tool used to bore a hole in a material by striking one end with a series of blows. 3. A machine for boring holes in the ground or in rock, e.g., in obtaining rock-core samples.

drill bit Same as bit, 1.

drilled-in caisson A composite foundation column; consists of a heavy wall pipe which is concrete-filled; the upper end is locked into the structure, and the lower end is secured in a socket in rock.

drilled pier, drilled pile A concrete pier or pile that is cast in place in a hole that has been bored in soil or rock.

drilled pile Same as augered pile.

drill press A drilling machine mounted in a stand; a handle is used to lower the drill (which rotates about a vertical axis) into the work.

drinking fountain A fixture consisting of a shallow basin, together with a water jet, designed to provide potable water for human consumption.

drinking-water cooler A factory-made assembly containing a small refrigeration system and having the primary functions of cooling potable water and dispensing such water.

drip, headmold, hoodmold, label, throating, weather molding 1. The outermost projecting molding around the top of a door or window, to discharge rainwater. 2. A throat, 2. 3. A pipe, or a steam trap and a pipe considered as a unit, which conducts condensation from the steam side of a piping system to the water or return side of the system. 4. A container that is typically installed at a low point in a gas piping system to collect condensate (i.e., liquids that may form within the gas system).

drip,4

drip bar Same as water bar.

drip cap A horizontal molding, fixed to a door or window frame to divert the water from the top rail, causing it to drip beyond the outside of the frame.

drip cap

drip channel A throat, 2.

drip course Same as dripstone course.

drip edge A strip which extends beyond other parts of a roof and which directs rainwater off the roof.

drip line An imaginary line described on the ground by the outer branch tips of a plant.

drip mold, drip molding Same as drip, 1.

drippage 1. An accumulation of liquid by dripping. 2. A dripping of water from the gutters or eaves of a house.

dripping eaves Sloping eaves which project beyond a wall and are not provided with a gutter so that water on the roof falls directly to the ground.

drip sink, lead safe A shallow sink set near floor level to receive the drip from a faucet or the like.

dripstone A drip cap made of stone.

dripstone

dripstone course A continuous horizontal drip molding on a masonry wall.

driptight Said of an enclosure constructed so that drops of liquid striking the enclosure (from a specified range of angles) cannot enter it.

drive band In pile driving, a steel band which encircles the head of a timber pile to prevent it from splitting when being driven.

drive cap A steel attachment placed over the top end of a pile to prevent damage while it is driven in the ground.

drive nail See drivescrew.

drive band

drive-in A retail business, bank, or motion-picture theater, designed to permit its patrons to receive services while they remain in their automobiles.

driven pile Any pile, such as a precast pile, which is driven into position at its final position at the site.

driven well A well constructed by driving a pipe into the ground; usually fitted with a well point and screen.

drivepipe A pipe, one end of which is sharpened for driving it into the ground; used to obtain a sample in situ, to reach water, etc.

drive point Same as well point.

drivescrew, screw nail A type of metal fastener; a helically threaded nail, driven with a hammer; has a higher withdrawal resistance than a nail with a plain shank; some types may be removed with a screwdriver.

drive shoe A reinforcement placed at the bottom of a pile to prevent damage to the pile during driving.

driveway A private way or road, which is primarily for use by automobiles.

driving band See drive band.

driving machine The power unit which applies the necessary energy to raise and lower an elevator or dumbwaiter car or to drive an escalator, moving walk, or the like.

driving resistance The number of blows of a pile-driving hammer which are required to advance the point of a pile a specified distance into the subsoil.

drn Abbr. for drain or drainage.

dromos The long, deep entrance passageway to an ancient Egyptian tomb or a Mycenaean beehive tomb.

dromos

droop The deviation from a preset value of a controlled liquid level, temperature, variable pressure, or differential pressure (at minimum controllable flow) when the flow through a regulator is gradually increased from its minimum controllable flow to its rated capacity.

drop 1. Any one of the guttae under the mutules or triglyphs of a Doric entablature. 2. In a cabinet lock, the vertical dimension from the finished edge of the lock to the center of the cylinder or tube. 3. In air conditioning, the vertical distance that a horizontally projected airstream falls from its original elevation when leaving an outlet, measured at the end of the throw. 4. Same as drop curtain. 5. Same as drop panel. 6. Of a stair, a fitting used to close the bottom end of a tubular newel. 7. Same as pendant, 2; also see corner drop. 8. Same as turned drop.

drop apron A strip of metal which is fixed vertically downward at eaves and gutters of a flexible-metal roof; acts as a drip.

drop arch A pointed arch which is struck from two centers that are nearer together than the width of the arch, so that the radii are less than the span; a depressed arch.

drop black See animal black.

drop bottom-seal See automatic door bottom.

drop box An electric outlet box hung from above, as in a theater stagehouse where it is fed by a cable from the overhead gridiron.

drop ceiling See dropped ceiling.

drop chute A device used to confine or to direct the flow of a falling stream of concrete; may be articulated or may be fabricated of heavy rubberized canvas.

drop cloth A large sheet of cloth, paper, or plastic which is spread over a floor, furniture, etc., as a protection against paint drippings and splatter.

drop cord An electric-light cord suspended and energized from a ceiling outlet.

drop curtain On the theater stage, any curtain that moves up and down, rather than from side to side.

drop elbow A pipe elbow, 1 having lugs on the sides for attaching it to a support.

drop ell Same as drop elbow.

drop escutcheon An escutcheon having a pivoted plate which covers a keyhole.

drop hammer A heavy weight for driving a pile into the ground; dropped by gravity along a set of guide rails onto the head of the pile.

drop handle A door handle that hangs vertically when not in use; often fabricated of brass or wrought iron.

drop handle

drop-head window A double-hung window whose lower sash can drop through the window sill into a pocket below the sill.

drop-in beam A simple beam, usually supported by cantilever arms, with joints so placed that it can be installed by lowering it into position.

drop key plate A key plate having a cover which swings over the key hole to protect it.

droplight 1. An electric lamp suspended from the ceiling on a flexible cord. 2. An electric lamp, sometimes protected by a wire guard, etc., on the end of a flexible cord; used as a portable work light.

drop molding A panel molding recessed below the surface of the surrounding styles and rails.

drop ornament A tear-shaped pendant, or a representation thereof.

drop-out ceiling A suspended ceiling system having listed translucent or opaque, heat-sensitive panels; when subject to heat, these panels drop from the suspension system, thereby exposing the sprinkler system installed above it.

drop panel On the lower side of a flat concrete slab, the thickened portion which surrounds a column, column capital, or bracket.

drop panel form A concrete form which is so erected as to provide the necessary support, shape, and finish for a drop panel.

dropped ceiling, drop ceiling 1. A suspended ceiling. 2. See soffit.

dropped escutcheon Same as key drop.

dropped girder A girder which is dropped below the floor joists and supports them.

dropped girder

dropped girt, dropped girth A girt which is dropped below the floor joists and supports them.

dropped roof The roof of an addition to a house, usually a flat surface of single pitch with its upper edge somewhat below the eaves of the house.

drop-point slating See diagonal slating.

drop ring A ring which is used as a handle to operate a lock or latch; the ring remains in a dropped position when not in use, but it may be raised and pivoted about the spindle to operate the lock.

drop siding, novelty siding, rustic siding An exterior wall cladding of wooden boards (or strips of other material such as aluminum or vinyl), which are tongued and grooved or rabbeted and overlapped so that the lower edge of each board interlocks with a groove in the board immediately below it.

drop siding

drop spreader In landscape architecture, a spreader, 1 for metering and distributing grass seed and/or fertilizer over a given area.

drop tee A pipe tee having lugs in the sides by which it can be attached to a support.

drop tracery Tracery hanging from the soffit of an arch.

drop vent In plumbing, a special individual vent which connects to a drain or vent pipe at a point below the fixture served.

drop window A vertically sliding window in which the sash can descend into an opening below the sill so that the entire window is open for ventilation.

drop wire The electric conductor extending from an outdoor pole to a building.

drove A mason’s chisel having a blade from 2 to 4 in. (5 to 10 cm) broad; a boaster.

drove chisel Same as boaster.

drove work Stone which has been dressed with a drove; same as boasted work.

drum 1. One of the cylinders of stone which form a column. 2. A round or polygonal wall below a dome, often pierced with windows. 3. The bell of Composite or Corinthian capitals.

drum hoist Same as hoist, 2.

drum paneling A form of door construction in which the panels are flush on both sides and covered with cloth or leather.

drum,1

drum tower A round tower whose diameter is greater than its height.

drum trap In plumbing, a cylindrical trap, with its axis in a vertical direction, having a cover plate which may be unscrewed for access; commonly used on the drainpipe from a bathtub or under a bathroom floor.

drum trap

drunken saw, wobble saw A circular saw having a blade which is set so that it does not rotate in one plane; used to cut a groove or kerf.

druxy A piece of wood that has lost its strength and become brittle.

drwl Abbr. for dry wall.

dry area A covered area, below grade, be-tween a basement wall and a retaining wall beyond it; its function is to keep the basement wall dry.

dry-batch weight The weight of the materials, excluding water, used to make a batch of concrete.

dry-bond adhesive See contact adhesive.

dry-bulb temperature The air temperature indicated by a dry-bulb thermometer after correction for the effects of radiation.

dry-bulb thermometer 1. An ordinary thermometer. 2. The one of two thermometers in a psychrometer which has an unmoistened bulb.

dry-butt joint A joint in stone masonry that is laid without mortar.

dry chemical extinguishing system A fire extinguishing system which is used to distribute an approved fire-extinguishing chemical by means of a gas under pressure. Fixed piping and nozzles aid in ensuring proper distribution of the chemical.

dry concrete Concrete having a low proportion of water so that the plastic mixture is relatively stiff; suitable for use in dry locations; esp. advantageous where large masses are poured and compacted and on sloping surfaces.

dry construction The use of dry materials such as gypsum board, plywood, or wallboard in construction, without the application of plaster or mortar.

dry course The first ply of built-up roofing laid directly over insulation or on a structural deck without the application of bitumen.

dry-dash finish The finish produced on an exterior stucco wall by throwing small pebbles on the stucco when it is partially dry.

dry density The density of soil, or the like, after it has been heated at a temperature of 221°F (105°C) to a dry condition.

dryer See drier.

dry film thickness The thickness of a dried coating of paint.

dry filter A filter for cleaning air which removes dirt by straining or filtering the air through various types of screens, fiberglass, or the like.

dry gas Gas having a moisture and hydrocarbon dew point below any normal temperature to which the gas piping will be exposed.

dry glazing 1. Any method of securing glass in a frame by use of a dry, preformed resilient gasket, without the use of a glazing compound. 2. Patent glazing.

dry hide The hiding power of a coating of paint after it has completely dried.

dry hydrate A finely ground hydrated lime, made from calcium or from dolomitic limestone.

drying The physical change of a liquid paint or varnish film which results in a hard surface, as a result of the loss of solvent, or a chemical reaction, or a combination of both. Also see air drying, forced drying.

drying agent See soluble drier.

drying creep Creep that results from drying.

drying inhibitor A substance added to paints and varnishes to prevent too rapid drying or skin drying; used to promote a high gloss and to avoid a wrinkled film.

drying oil, paint oil A vegetable oil which oxidizes easily on exposure to air and forms a hard, dry film; esp. useful in paints.

drying shrinkage The contraction of plaster, cement paste, mortar, or concrete caused by loss of moisture.

dry joint A joint without mortar.

dry kiln An oven for drying and seasoning cut lumber.

dry laid Said of masonry that has been laid without the use of mortar.

dry lining 1. The surfacing a wall with gypsum lath, without the application of wet plaster. 2. (Brit.) Same as Dry Wall.

dry masonry Masonry laid without mortar.

dry mix A mixture of mortar or of concrete which contains little water in relation to its other components.

dry mixing Blending of solid materials for mortar or concrete prior to adding the mixing water.

dry-mix shotcrete Shotcrete which is conveyed pneumatically; most of the mixing water is added at the nozzle.

dry moat Around a medieval fortification, a deep, broad trench not filled with water.

dry mortar A mortar whose constituents are so proportioned that it is markedly stiffer than usual, yet with sufficient water for hydration.

dryout A condition in gypsum plaster caused by water evaporating out of the plaster before it sets. Such plaster is soft, powdery, and usually light in color.

dry-pack To ram forcibly a slightly moist portland cement-aggregate mixture into a confined area, as into the space between the top of concrete pier underpinning and the bottom of the building being underpinned. Here the dry-pack serves as a low-shrinkage filler material that transmits the load of the building to the underpinning.

dry-packed concrete A concrete mixture sufficiently dry to be consolidated only by heavy ramming.

dry partition A partition erected and finished without the application of wet plaster.

dry-pipe sprinkler system 1. A complete fire-protection sprinkler system with sprinkler heads in which there is no water unless the system is actuated (either automatically or manually) in case of fire; esp. used in areas subject to freezing temperatures, or to avoid the hazards of leaking or bursting pipes. 2. A fire sprinkler system containing a network of pipes filled with air or nitrogen under pressure and equipped with an automatic sprinklers; when the sprinklers open, the air or nitrogen is released, thereby opening a valve (called a “dry-pipe valve”) which permits water to enter the pipes and to flow out the opened sprinklers.

dry-pipe valve The control valve for a dry-pipe sprinkler system which activates the system; must be in a location where it is protected against mechanical injury and freezing.

dry-powder fire extinguisher One that discharges a fine, dry powder (usually sodium bicarbonate, potassium bicarbonate, or ammonium phosphate) by the pressure of a gas stored in the same container as the powder; generally suitable for class-B and class-C fires.

dry press A mechanical press for forming brick, cast stone, or other ceramic articles from slightly moistened granular mixtures; pressure is applied to both top and bottom of the die box.

dry-press brick Brick formed in molds under high pressures from relatively dry clay (5 to 7% moisture content).

dry-process enameling A porcelain enameling process in which the metal article is heated to a temperature above the maturing temperature of the coating; then the coating materials are applied to the hot metal, in the form of a dry powder, and fired.

dry return In a steam heating system, a return pipe which carries both water of condensation and air.

dry riser inlet Same as fire department connection.

dry riser system Same as dry standpipe system.

dry rising main British term for dry standpipe.

dry-rodded volume The volume which an aggregate occupies when compacted dry under the standardized conditions used in measuring unit weight of aggregate.

dry-rodded weight The weight per unit volume of an aggregate when compacted dry under standardized conditions.

dry rodding In measuring the weight per unit volume of coarse aggregates, the process of compacting dry material in a calibrated container by rodding under standardized conditions.

dry rot The decay of seasoned wood caused by fungi of a type capable of carrying water into the wood they infest.

dry rubble construction Masonry of rubble which is laid without mortar.

dry saturated steam, dry steam Steam containing no water in suspension.

dry shake See monolithic surface treatment.

dry sheet A nonbituminous felt or a light roofing paper applied between the roof-deck and the roofing material to prevent adherence of the roofing to the roof-deck and to isolate the roofing from movements of the roof-deck.

dry shotcrete Concrete or mortar which is pumped through two separate hoses and mixed; one hose contains the dry materials and the other contains water. The mixture is projected through a nozzle at high velocity onto a surface.

dry sprinkler Same as dry-pipe sprinkler system.

dry sprinkler system See dry-pipe sprinkler system.

dry-stacked surface-bonded wall A wall built of a combination of two or more masonry units of different material bonded together, one forming the backup and the other the facing of the combination.

dry standpipe A standpipe that is not normally filled with water but to which water can be supplied (through a fire department connection) in the event of fire.

dry standpipe system A standpipe system that is normally dry.

dry steam See dry saturated steam.

dry stock See dry wood.

dry stone wall A wall composed of stones not cemented with mortar.

dry strength The strength of an adhesive joint determined immediately after drying under specified conditions, or after a period of conditioning in the standard laboratory atmosphere.

dry system See dry-pipe sprinkler system.

dry-tamp process The placing of concrete or mortar by hammering or ramming a relatively dry mix into place.

dry timber Timber from which all moisture has been removed.

dry topping See monolithic surface treatment.

dry-type transformer A transformer whose core and coils are not immersed in an insulating oil.

dry vent A vent which carries neither water nor waterborne wastes.

dry-volume measurement Measurement of the ingredients of grout, mortar, or concrete by their bulk volume.

dry wall 1. An interior wall, constructed with a dry-wall finish material such as gypsum board or plywood; also see dry construction. 2. In masonry construction, a self-supporting rubble or ashlar wall built without mortar.

dry-wall construction Same as dry construction.

dry-wall finish An interior covering material such as gypsum board or plywood, which is usually applied in large sheets or panels; does not require a water additive to apply.

dry-wall frame A type of knocked-down door-frame; designed for installation in a wall which is constructed with studs and a dry sheet facing material (such as gypsum board) after the wall is erected.

dry wall partition A partition constructed without the application of wet plaster.

dry weight The dry density of a material multiplied by its volume.

dry well 1. A covered pit either with open-jointed lining or filled with coarse aggregate through which drainage from roofs, basement floors, foundation drain tiles, or areaways may seep or leach into the surrounding soil. 2. Same as cesspool. 3. An absorbing well.

dry wood 1. (US) Wood dried to a moisture content of from 15 to 19%. 2. (Brit.) Wood dried to a moisture content of from 15 to 23%.

DS On drawings, abbr. for downspout.

D.S., D/S, D/Sdg Abbr. for drop siding.

DSGN On drawings, abbr. for “design.”

DT On drawings, abbr. for drum trap.

DT&G Abbr. for “double tongue and groove.”

DU On drawings, abbr. for disposal unit.

dual duct A duct, having a continuous internal divider, to provide two individual raceways for installation of two separate electric wiring systems (such as one for electric power and one for a sound system).

dual-duct system An air-conditioning system in which two supply ducts run to each space being conditioned, one for cold air, the other for warm air; at each individually controlled space, air from the two ducts is blended in a sheet-metal box (called a “mixing box”) and then supplied to the conditioned space.

dual-duct terminal unit Same as “mixing box”; see dual-duct system.

dual-element fuse A fuse which has current-responsive elements of two different fusing characteristics in series.

dual-fiber cable Optical fiber cable composed of two single-fiber cables enclosed in an extruded plastic overjacket; may have a rip cord for peeling back the overjacket to access the fibers.

dual-flush water closet A water closet providing a choice of two flushing mechanisms. One button makes a full flush available; the other uses only about half the amount of water.

dual-fuel system A heating system in which the boiler can burn either of two fuels, usually oil and gas in the US; usually one is the primary fuel and the other is used for standby purposes.

dual glazing Same as double glazing.

dual-head nail Same as double-headed nail.

dual-pitched roof A roof having a double slope on both sides of a central ridge; for example, a gambrel roof.

dual-temperature system A hot water system that supplies hot water at two different temperatures.

dual vent, common vent, unit vent In plumbing, a single vent, 1 connected at the junction of two fixture drains, which serves as a vent for both.

dual vent

dub To strike, cut, rub, or dress so as to smooth a surface.

dubbing out, dubbing 1. Filling in hollow and irregular surfaces and leveling walls with plaster before regular plasterwork. 2. Forming, very roughly, a plaster cornice, before the final plaster coat is applied.

duck See mouse.

duckboard 1. A cat ladder. 2. A wooden walk-way across muddy ground, a wet floor, etc.

duckfoot bend Same as rest bend.

duck tape A tape of heavy cotton or synthetic fabric which is impregnated with a sealing compound, such as asphalt or an elastomer.

duct 1. See air duct. 2. In electric systems, a metallic or nonmetallic tube, (usually circular, oval, rectangular, or octagonal) for housing wires or cables; may be underground or embedded in concrete floor slabs.

duct fan See tubeaxial fan.

duct furnace A unit heater having a burner and heat exchanger, but not a fan; located in a duct system which is provided with a fan for moving the air.

ductile Capable of being stretched or deformed without fracturing.

ductile-iron pipe A pipe that is fabricated of a cast-iron alloy in which graphite replaces the carbon that is present in cast-iron; provides the same advantages as cast-iron pipe along with the added advantage of a higher external load-bearing capacity; not as brittle as cast-iron pipe (thus permitting rougher handling) but higher in cost.

ductility index The ratio of the total deformation at maximum load to the elastic limit deformation.

duct lining A fiberglass blanket material used as a lining inside a sheet-metal duct of an air-conditioning system; reduces noise which is transmitted along the duct and provides thermal insulation.

duct sealing compound A resilient substance used to seal the ends of a cable duct or conduit.

duct sheet A coiled or flat sheet of a gauge width and thickness suitable for use in duct-work.

duct silencer Same as sound attenuator.

duct system A series of ducts and associated elbows, connectors, dampers, and air outlets used to convey air from a fan to the spaces served.

ductwork The ducts in a heating, ventilating, or air-conditioning system.

due care The standard of reasonable care, skill, ability, and judgment which, if not met, constitutes negligence; such a standard may be imposed by contract or by operation of law in the absence of a contract. This term implies the performance of duties and services by a professional which is consistent with the level of performance provided by reputable professionals in the same geographical area at the same period of time.

dugout A primitive shelter, often consisting of an excavation in a bank of sloping terrain that is roofed with bark laid over a pole framework, then covered with sod; also see half-dugout.

dug well A well for water, constructed by excavating a large-diameter shaft and installing a casing.

dumbbell tenement A multiple-dwelling substandard apartment building; commonly three to five stories high, containing relatively long narrow apartments within it; has windows only at the front and rear of each apartment. Shafts located on one or both sides of the apartment provide air and a little light in the rooms that do not face the front or rear of the building. The floor plan of each floor resembles the outline of a dumbbell. Also called a railroad flat.

dumbwaiter A hoisting and lowering mechanism within a building equipped with a relatively small car which moves in a vertical direction (in guides); used exclusively for carrying materials.

dummy cylinder For a door lock, a mock cylinder which has no operating mechanism.

dummy joint Same as groove joint.

dumped fill Excavated material, usually end-dumped from trucks, with no special effort made to spread or compact it.

dumpling A large unexcavated mass, usually at the center of an excavated area, which is left undisturbed; may be removed when the work nears completion.

dump truck Any type of truck whose body can be tilted to discharge its load.

dumpy level A surveying instrument used in the direct measurement of differences of elevation; consists of a telescope and a spirit level (which is parallel to the telescope and mounted below it); the telescope is permanently attached to leveling base.

dumpy level

dungeon 1. The principal and strongest tower of a castle; the keep. 2. A dim chamber in a medieval castle, usually at the base of the keep.

dungeon,1

dunnage 1. Pieces of timber which are used to provide structural support for a large item of equipment on a rooftop. 2. Members that form a structural support for a cooling tower or the like, but are not part of the building structure itself.

dunter machine See surfacer, 3.

duomo A cathedral; properly, an Italian cathedral.

duomo at Brescia, shown in section

DUP On drawings, abbr. for “duplicate.”

duplex 1. A duplex apartment. 2. A duplex house.

duplex apartment A separate dwelling in an apartment building, having rooms on two levels, with self-contained vertical circulation.

duplex burner In a heating system, a gas burner having two sections which can either burn together at full load or be used singly for reduced heating.

duplex cable An electric cable consisting of two individually insulated conductors which are twisted together.

duplex-head nail Same as double-headed nail.

duplex house, two-family house A house having quarters, with separate entrances, for two families; usually a two-story house with a separate apartment on each floor.

duplex outlet See duplex receptacle.

duplex receptacle In electric wiring, two receptacles, combined as a single unit, for installation in an outlet box.

duplex receptacle

durability 1. The ability of a material, component, assembly, or building to resist weathering action, chemical attack, abrasion, and other conditions of service. 2. The resistance of a particular species of wood to decay.

durability factor A measure of the change (with time) in the property of a material as a result of exposure to an influence which has the potential of causing deterioration; usually expressed as a percentage of the property before exposure.

duraluminum An alloy containing principally aluminum, approximately 4% copper, 0.2 to 0.75% magnesium, and 0.4 to 1% manganese; individual manufacturers may include small amounts of silicon and iron.

duramen See heartwood.

durbar In India, an audience hall in the palace of a prince.

Durham fitting See drainage fitting.

Durham system A soil or waste system where all piping is of threaded pipe, tube, or other such rigid construction, using recessed drainage fittings.

durn A vertical member on each side of a door, usually formed of a solid timber.

durometer An instrument for measuring the degree of hardness of a material; also see shore hardness.

dust board 1. A panel placed above a built-up cornice to prevent the entry of dust. 2. A paneled division between wooden drawers.

dust collector An accessory device used to prevent dust, which a tool or machine produces, from escaping into the surrounding air; suction forces the dust-laden air into a bag or chamber, where it is collected.

dust cover box Same as plaster guard.

dust dry Same as dustfree.

dustfree Descriptive of the stage in the drying of a paint or varnish film at which dust will no longer stick to the surface.

dust-free time The time required for a freshly applied paint or compound to form a skin on its surface so that dust will not adhere to it.

dusting The development of a powdered material at the surface of hardened concrete.

dust-laying oil Oil of sufficiently low viscosity to be applied without preheating; may be a slow-curing asphaltic product or a nonvolatile petroleum distillate containing no asphalt; applied over unpaved surfaces.

dustproof So constructed or protected that the accumulation of dust will not interfere with successful operation.

dustproof strike A strike plate equipped with a spring plunger that completely fills the bolt hole when the bolt of the lock is not projected into it.

dust-tight Descriptive of an enclosure which is so constructed (with gaskets, etc.) as to prevent the entry of dust.

Dutch arch, French arch A flat arch in brick; most of the bricks slope outward from the middle of the arch (at the same angle on both sides of the centerline) and do not have radial joints. Properly not an arch. Same as flat arch.

Dutch barn 1. A distinctive type of front-gabled barn of curtain wall, 1 construction, erected by early Dutch settlers in America; approximately square in plan; built on stone piers with a steeply pitched roof. Often sheathed with overlapping planks to shed water readily; the outer planks temporarily removable for maintenance; typically had a small pent roof directly over the entryway for wagons; owl holes near the peaks of the gables for ventilation and for access to the barn for mice-eating birds. 2. Same as bank barn. 3. Same as hay barrack.

Dutch bond 1. Same as English cross bond. 2. Same as Flemish bond.

Dutch brick A hard yellow brick often used in the interior of Dutch Colonial houses; commonly laid in the floor of the fireplace hearth that extended into the room. Occasionally, this term refers to a brick having a thickness of only about 1½ inches (3.8 cm). Also see klinkart.

Dutch Colonial architecture A broad term describing the architecture prevalent in the Dutch-settled parts of America during the early part of the 17th century. The earliest houses were simple one-story, single-room permanent dwellings.

In rural areas, the design of houses depended primarily on available building materials. Where stone was abundant, houses were built with thick stone walls; where suitable clay was available, houses were built of brick, usually laid in a Flemish bond pattern; where timber was plentiful, the houses were of wood construction with siding of wide weatherboarding. Common characteristics included: a roof covering of wood shingles or tiles; steeply pitched gables with parapets; Dutch gambrel roofs with flared eaves having a considerable overhang; straight-line gables; a chimney located in a thick exterior wall at a gable end or gambrel end of the house; casement windows with small panes and battened shutters; a Dutch door; heavy plank floors, bake ovens.

In urban areas such as New Amsterdam, houses were typically two and a half or three and a half stories high, although those in which the owners also conducted a business on the ground floor and lived in the floors above were four or five stories high. Common characteristics included: thick exterior walls usually having a rough timber structure, faced with a brick veneer laid in a Flemish bond pattern with the facing secured to the timber framing by decorative wrought-iron anchors; where wood was plentiful, wide weatherboarding used as siding instead of brick facing; stone walls in regions where stone was commonly available; a parapeted gable-end wall often facing the street; typically, corbie gables or steeply pitched straight-line gables; often, a gambrel roof with flared eaves; usually, a brick chimney within the exterior walls, topped with a chimney cap; casement windows with small glass panes in cames; battened shutters (later replaced by double-hung windows); a Dutch door or paneled double door, often with a transom light above; usually an exterior stoop in front of the door.

Dutch Colonial Revival Revival architecture from the late 19th century onward, loosely based on the Dutch Colonial prototypes described previously, including a gambrel roof, flared eaves, Dutch doors, and multipaned double-hung windows. Revival houses often retain many of the characteristics of their prototypes, but differ significantly as a result of modern additions such as a gambrel roof with dormers, wood shutters having decorative designs cut through the shutters, and cross gambrels.

Dutch diaper bond Same as English cross bond.

Dutch door A door consisting of two separate leaves, one above the other; the leaves may operate independently or together.

Dutch door: exterior elevation; interior elevation

Dutch door bolt A device which fastens together the upper and lower leaves of a Dutch door so that they open and close as a single unit.

Dutch dormer See shed dormer.

Dutch gable 1. Same as Flemish gable. 2. A corbie gable.

Dutch gambrel roof A type of gambrel roof that has two flat surfaces on each side of the ridge of the roof. The initial downward slope from the roof ridge is an angle of about 22 degrees, then steepens to an angle of about 45 degrees. Near the lower end, the pitch is much less and the roof has flared eaves. Compare with English gambrel roof, New England gambrel roof, Swedish gambrel roof.

Dutch kick A roof having flared eaves, as in a Dutch gambrel roof.

Dutch lap A method of applying shingles, slates, etc.; each shingle overlaps one below and one to the side.

Dutch lap

Dutch light A removable glazed sash, used in greenhouses.

dutchman 1. A small piece or wedge inserted as filler to stop an opening. 2. A small piece of material used to cover a defect, to hide a badly made joint, etc. 3. A short lead nipple used to join two pipes which are otherwise not long enough to be joined.

Dutch method of application A method of applying rectangular roofing shingles which provides a lap at the top and one side, thereby forming a square or rectangular pattern.

Dutch oven Same as bake oven.

Dutch roof Occasionally, a synonym for a Dutch gambrel roof.

Dutch shutter A shutter, 2 whose upper and lower sections can be opened and closed independently of each other.

Dutch slice-hip roof A Dutch gambrel roof in which each end has been clipped off, as in a jerkinhead roof.

Dutch slice-hip roof

Dutch stoop A small wooden porch having a wood bench along each side of the entry door; may be covered by a cantilevered hood.

Dutch tile A flat, square, decorative tile from Holland often used on the faces of fireplaces; different colors were once available, but Delft blue tiles were probably the most popular.

DVTL On drawings, abbr. for dovetail.

dwang 1. A crowbar or similar tool. 2. A strut inserted between timbers to stiffen them.

dwarf door A door whose height is somewhat less than normal.

dwarf gallery A passage on the external surface of a wall screened by a small-scale arcade.

dwarf partition A partition which does not extend to full ceiling height.

dwarf rafter Same as jack rafter.

dwarf wainscoting Wainscot that is restricted to the lower part of a wall.

dwarf wall 1. A wall of less height than a story of a building. 2. A wall which supports the sleeper joists under the lowest floor of a building.

dwelling A building designed or used as the living quarters for one or more families.

dwelling unit One or more rooms in a building designed as living accommodations for one or more families.

dwg, DWG Abbr. for “drawing.”

D-window 1. Same as semicircular fanlight. 2. A semicircular window, 2.

DWV Abbr. for “drainage, waste, and vent.”

DWV tubing See type-DWV tubing.

dye A coloring material or compound that imparts color throughout a material by penetration.

dyke See dike.

Dymaxion House An unconventional lightweight house developed and patented in 1928 by R. Buckminster Fuller (1895-1983); originally called the 4-D house, and intended as a prefabricated unit. Octagonal or circular in plan, this experimental house was supported by a massive central shaft that housed all building services, such as electrical and plumbing systems.

dynamic Said of a structure whose physical behavior characteristics are time-related, i.e., are nonstatic.

dynamic analysis The analysis of a structural system as a function of displacement under transient loading conditions.

dynamic balancing See balancing.

dynamic load Any load which is nonstatic, such as a wind load or a moving live load.

dynamic loading Loading by a piece of machinery or equipment which imposes a load in addition to its static load, as a result of its vibration or movement.

dynamic modulus of elasticity The modulus of elasticity of a test specimen which is computed from physical characteristics of the specimen (size, weight, and shape) and from its fundamental frequency of vibration.

dynamic penetration test A penetration test in which penetration into the soil results from the application of a series of blows on a testing device.

dynamic pile formula Any of several formulas by which the bearing capacity of a driven pile can be calculated from the energy of the pile hammer and the penetration of the pile under each blow.

dynamic pressure The pressure on the inner surface of a pipe when water flows through it; this pressure is in excess of that when the water is at rest.

dynamic resistance The resistance of a pile (or the like) to blows from a pile hammer, expressed in blows per unit depth of penetration.

dynamics That part of the science of mechanics which treats the motion of bodies and the action of forces in producing or changing their motion.

dyostyle Same as distyle.