Glossary

A

AAC

See Autoclaved aerated concrete.

AAMA

American Architectural Manufacturers Association, a trade organization that develops standards for windows, doors, skylights, storefront, and curtain wall systems.

AC

See Articulation class.

Accelerating admixture

An admixture that causes concrete or mortar to cure more rapidly.

Access flooring

A raised finish floor surface consisting of small, individually removable panels beneath which wiring, ductwork, and other building services may be installed.

Access standard

A set of regulations or technical standards ensuring that buildings are accessible and usable by physically handicapped members of the population.

Acoustical ceiling

A ceiling of fibrous tiles that are highly absorbent of sound energy.

ACQ

See Alkaline copper quat.

Acrylic

A transparent plastic material widely used in sheet form for glazing windows and skylights; a modifier added to plasters, paints, and cements to enhance various performance properties of the material.

Active metal

A metal relatively high on a galvanic series, tending to act as an anode in galvanic couples.

Actual dimension

The true dimension of a material, as distinct from its nominal dimension.

ADA

See Airtight drywall approach.

ADA

See Americans with Disabilities Act.

Admixture

In a concrete or mortar, a substance other than cementitious material, water, and aggregates included in the mixture for the purpose of altering one or more properties of the mixed material, either in its plastic working state or after it has hardened.

Advanced framing techniques

A wood light framing system that minimizes redundant framing members, reducing the amount of lumber required and increasing the thermal efficiency of the insulated frame.

Aerogel

A silicon-based foam with relatively high thermal resistance, used in insulating blankets and insulated glazing units.

AESS

See Architecturally exposed structural steel.

Aggregate

Inert particles, such as sand, gravel, crushed stone, or expanded minerals, in a concrete, mortar, or plaster.

Air barrier

A material that reduces air leakage through a building assembly.

Air barrier assembly

An interconnected assemblage of materials that can effectively resist air pressure differentials acting across the boundary of a wall, roof, or floor assembly.

Air barrier system

An interconnected collection of air barrier assemblies responsible for the overall air leakage performance of a completed building.

Air-entraining admixture

An admixture that causes a controlled quantity of stable microscopic air bubbles to form in concrete or mortar during mixing, usually for the purposes of increasing workability and resistance to freeze-thaw conditions.

Air permeance

A measure of a material's permeability to airflow. A low air ­permeance is a desirable characteristic of an air barrier material.

Air-supported structure

A structure, usually long span, with a fabric roof ­supported by a higher air pressure inside the structure relative to outside the structure.

Airtight drywall approach (ADA)

An air barrier system relying on gypsum board interior finish and the sealing of joints between framing members of a light frame building, serving to restrict the flow of air through the exterior walls and roof.

AISC

American Institute of Steel Construction. A trade association that establishes standards for the use of structural steel in buildings and other structures.

Albedo

See Solar reflectance.

Alkaline copper quat (ACQ)

A chemical used to preserve wood against attack by decay and insects.

Alloy

A substance composed of two or more metals or of a metal and a nonmetallic constituent.

Aluminum

A silver-colored, nonferrous metal that naturally forms a self-protecting oxide layer.

Americans with Disabilities Act (ADA)

A federal regulation establishing equal ­access for persons with disabilities to public accommodations, commercial ­facilities, and transportation facilities.

Anchor

Any of a variety of mechanical devices used to fasten or connect one material or member to another.

Anchor bolt

A bolt embedded in ­concrete for the purpose of fastening a building frame to a concrete or masonry foundation.

Angle

A structural section of steel, ­aluminum, or other material whose ­profile resembles the letter L.

Angle of repose

See Maximum allowable slope.

Annealed

Cooled under controlled conditions to minimize internal stresses, ­usually referring to iron or steel members.

Anode

The metal in a galvanic couple that experiences accelerated corrosion.

Anodizing

An electrolytic process that forms a permanent protective oxide coating on aluminum, with or without added color.

ANSI

American National Standards Institute. An organization that fosters the establishment of voluntary industrial standards.

Anticlastic

Saddle-shaped or having curvature in two opposing directions.

APP

See Atactic polypropylene.

Appearance grading

The grading of wood for its appearance, as distinct from its structural properties; not to be confused with visual grading.

Apron

The finish piece that covers the joint between a window stool and the wall finish below.

Arch

A structural device that supports a vertical load by translating it into axial inclined forces at its supports.

Architectural concrete

Concrete intended as a finish surface and produced to a higher-quality standard.

Architecturally exposed structural steel (AESS)

Structural steel intended to be left exposed in the finished building and fabricated and installed to a higher-­quality standard.

Architectural sheet metal roofing

A roof covering made up of sheets of metal in a traditional shop- or site-fabricated pattern such as standing seam, flat seam, or batten seam.

Architectural Woodwork Institute (AWI)

A trade organization that develops standards for custom millwork.

Arc welding

A process of joining two pieces of metal by melting them together at their interface with a continuous electric spark and adding a controlled additional amount of molten metal from a metallic electrode.

Area divider

A curb used to partition a large roof membrane into smaller areas to allow for expansion and contraction in the deck and membrane.

Articulation class (AC)

A measure of a finish ceiling's absorption and reflection of sound, particularly with regard to speech clarity in an open office environment.

Ash dump

A door in the underfire of a fireplace that permits ashes from the fire to be swept into a chamber beneath, from which they may be removed at a later time.

Ashlar

Squared stonework.

Asphalt

A tarry brown or black mixture of hydrocarbons; one type of bitumen.

Asphalt roll roofing

A continuous sheet of the same roofing material used in asphalt shingles.

Asphalt-saturated felt

A water-resistive sheet material, available in several different thicknesses, usually consisting of matted cellulose fibers that have been impregnated with asphalt; used to provide a weather-protective layer in an exterior wall or roof assembly; also called building felt.

Asphalt shingle

A roofing unit composed of a heavy organic or inorganic felt saturated with asphalt and faced with mineral granules.

ASTM

Formerly, American Society for Testing and Materials. An organization that promulgates standards for testing, materials, and methods of building construction.

Atactic polypropylene (APP)

An amorphous form of polypropylene used as a modifier in modified bitumen roof membrane.

Auger

A helical tool for creating cylindrical holes.

Autoclaved aerated concrete (AAC)

Concrete formulated so as to contain a large percentage of gas bubbles as a result of a chemical reaction that takes place in an atmosphere of steam.

AWI

See Architectural Woodwork Institute.

Awning window

A window that pivots on a horizontal axis at the top edge of the sash and projects toward the outdoors.

Axial

In a direction parallel to the long axis of a structural member.

B

Backer board

A moisture-resistant board, used as a base for thin-set tile applications, usually composed of fiber-­reinforced cement or glass-mat-faced gypsum.

Backer rod

A flexible, compressible strip of plastic foam inserted into a joint to limit the depth to which gunnable sealant can penetrate.

Backfill

Earth or earthen material used to fill the excavation around a foundation; the act of filling around a foundation.

Backup bar

A small rectangular strip of steel applied beneath a joint to provide a solid base for beginning a weld between two steel structural members.

Backup wall

A vertical plane of masonry, concrete, or wood framing used to support a thin facing such as a single wythe of brickwork.

Ballast

A heavy material installed over a roof membrane to prevent wind uplift and shield the membrane from sunlight.

Balloon frame

A wooden building frame composed of closely spaced ­members nominally 2 inches (50 mm) thick, in which the wall members are single pieces that run from the top of the foundation to the underside of the roof framing.

Baluster

A vertical member that serves to fill the opening between a handrail and a stair or floor.

Band joist

A wooden joist running ­perpendicular to the primary direction of the joists in a floor and closing off the floor platform at the outside face of the building. Also called a rim joist.

Bar

A small rolled steel shape, usually round or rectangular in cross section; a steel reinforcing bar used for reinforcing concrete.

Barrel shell

A scalloped roof structure of reinforced concrete that spans in one direction as a barrel vault and in the ­other as a folded plate.

Barrel vault

A segment of a cylindrical surface that spans as an arch.

Barrier wall

An exterior wall of a building whose watertightness depends on its freedom from passages through the wall. Also called a face-sealed wall.

Basalt

A dense and durable igneous rock, usually dark gray; classified by ASTM C119 in the Granite group.

Baseboard

A strip of finish material placed at the junction of a floor and a wall to create a neat intersection and to protect the wall against damage from feet, furniture, and floor-cleaning ­equipment.

Base-coat plaster

One or more preparatory plaster coats that provide a flat, solid surface suitable for the application of the final finish coat plaster. See also Scratch coat and Brown coat.

Base flashing

The flashing at the edges of a low-slope roof membrane that turns up against the adjacent face of a parapet or wall; frequently overlapped by a counterflashing.

Base isolator

A device at foundation level that diminishes the transmission of seismic motions to a building.

Baseplate

A steel plate inserted between a column and a foundation to spread the concentrated load of the column across a larger area of the foundation.

Basic oxygen process

A steel-making process in which a stream of pure oxygen is introduced into a batch of molten iron so as to remove excess carbon and other impurities.

Batten

A strip of wood or metal used to cover the gap between two adjoining boards or panels.

Batten-seam

A seam, roughly square in profile, in architectural sheet metal roofing.

Batter board

Boards mounted on stakes outside the excavation area of a building, used to preserve locations for string lines marking the corners of the building foundation.

Bay

A rectangular area of a building defined by four adjacent columns; a portion of a building that projects from a facade.

Bead

A narrow line of weld metal or sealant; a strip of metal or wood used to hold a sheet of glass in place; a narrow, convex molding profile; a metal edge or corner accessory for plaster.

Beam

A linear or curved structural member that acts primarily to resist nonaxial loads.

Beam blank

See Bloom.

Bearing

A point at which one building element rests upon another.

Bearing block

A piece of wood fastened to a column to provide support for a beam or girder.

Bearing pad

A block of plastic or synthetic rubber used to cushion the point at which one precast concrete element rests upon another.

Bearing wall

A wall that carries structural loads from floors, roofs, or walls above.

Bed

See Casting bed.

Bed joint

The horizontal layer of mortar beneath a masonry unit.

Bedrock

A solid stratum of rock.

Bending moment

The combination of tension and compression forces that cause a beam or other structural member to bend. See also Moment.

Bending stress

A compressive or tensile stress resulting from the application of a nonaxial force to a structural member.

Bent

A plane of framing consisting of beams and columns joined together, often with rigid joints.

Bentonite clay

A colloidal clay that swells to several times its dry volume when saturated with water; the primary ingredient in bentonite waterproofing.

Bessemer process

An early method of steel manufacturing in which air was blown into a vessel of molten iron to burn out impurities.

Bevel

An end or edge that is cut at other than a right angle.

Bevel siding

Wood cladding boards that taper in cross section.

Billet

A large cylinder or rectangular solid of material.

BIM

See Building information modeling.

BIPV

See Building-integrated photovoltaic.

Birdsmouth cut

An angled notch cut into a rafter to allow the rafter to seat securely on the top plate of a wall.

Bite

The depth to which the edge of a piece of glass is held by its frame.

Bitumen

A tarry mixture of hydrocarbons, such as asphalt or coal tar.

Bituminous roof membrane

A low-slope roof membrane made from bituminous materials, either a built-up roof membrane or a modified bitumen roof membrane.

Blast furnace slag

A hydraulic cementitious material formed as a byproduct of iron manufacture, used in mortar and concrete mixtures; also called slag cement.

Blast-resistant glazing

Window, storefront, or curtain wall systems designed for resistance to the force of explosive blasts.

Bleed water

In freshly placed concrete, water that rises to the top surface of the concrete as the solid cement and aggregate particles settle.

Blended hydraulic cement

Hydraulic cement made from a mixture of cementitious materials such as portland cement, other hydraulic cements, and pozzolans for the purpose of altering one or more properties of the cement or reducing the energy required in the cement manufacturing process.

Blind nailing

Attaching boards to a frame, sheathing, or subflooring with toe nails driven through the edge of each piece so as to be completely concealed by the adjoining piece.

Blind-side waterproofing

An impervious layer or coating on the outside of a foundation wall that, for reasons of inaccessibility, was installed before the wall was constructed.

Blocking

Pieces of wood inserted ­tightly between joists, studs, or rafters in a building frame to stabilize the structure, inhibit the passage of fire, provide an ­attachment surface for finish materials, or retain ­insulation.

Bloom

A rectangular solid of steel formed from an ingot as an intermediate step in creating rolled steel structural shapes.

Blooming mill

A set of rollers used to transform an ingot into a bloom.

Bluestone

A sandstone that is gray to blue-gray and splits readily into thin slabs; classified by ASTM C119 in the Quartz-Based Stone group.

Board foot

A unit of lumber volume, nominally 12 square inches in cross-­sectional area and 1 foot long.

Board siding

Wood cladding made up of boards, as differentiated from shingles or manufactured wood panels.

Bolster

A long chair used to support ­reinforcing bars in a concrete slab.

Bolt

A fastener, usually metallic, consisting of a cylindrical body with a head at one end and a helical thread at the other, intended to be inserted through holes in adjoining pieces of material and closed with a threaded nut.

Bond

In masonry, the adhesive force between mortar and masonry units, or the pattern in which masonry units are laid to tie two or more wythes together into a structural unit. In reinforced concrete, the adhesion between the surface of a reinforcing bar and the surrounding ­concrete.

Bond breaker

A strip of material to which gunnable sealant does not adhere.

Bond classification

A system for rating the durability of a structural wood panel under conditions of repeated wetting or long-term weather exposure.

Bonded posttensioning

A system of prestressing in which the tendons are grouted after stressing so as to bond them to the surrounding concrete.

Bonded terrazzo

Terrazzo flooring whose underbed is poured directly upon the structural floor.

Bottom bar

A reinforcing bar that lies close to the bottom of a beam or slab.

Bottom plate

See Sole plate.

Bound water

In wood, the water held within the cellulose of the cell walls. See also Free water.

Box beam

A bending member of metal or plywood whose cross section resembles a closed rectangular box.

Box girder

A major spanning member of concrete or steel whose cross section is a hollow rectangle or trapezoid.

Box nail

A nail with a slenderer shank than a common nail; used for fastening framing members in wood light frame construction.

Braced frame

A structural building frame strengthened against lateral forces with diagonal members.

Bracing

Diagonal members, either temporary or permanent, installed to stabilize a structure against lateral loads.

Brad

A small finish nail.

Brake

A machine used to form lengths of sheet metal into bent shapes.

Brake metal

Sheet metal, formed into final shape using a brake.

Brazing

A process that uses molten, nonferrous metal to join two pieces of metal. The brazing metal is melted at a temperature below that of the metals being joined, so that, unlike in welding, the joined metals remain in a solid state throughout the process.

Breather mat

A wiry plastic matting placed within a roof or wall assembly to create a space for drainage and ventilation.

Bridging

Bracing or blocking installed between steel or wood joists at intermediate points to stabilize the joists against buckling and, in some cases, to permit adjacent joists to share loads.

British thermal unit (BTU)

The quantity of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.

Broom finish

A skid-resistant texture imparted to an uncured concrete surface by dragging a stiff-bristled broom across it.

Brown coat

The second of two base-coat plaster applications in a three-coat plaster.

Brownstone

A brownish or reddish sandstone; classified by ASTM C119 in the Quartz-Based Stone group.

BTU

See British thermal unit.

Buckling

Structure failure by gross lateral deflection of a slender element under compressive stress, such as the sideward buckling of a long, slender column or the upper edge of a long, thin floor joist.

Building brick

Brick used for concealed masonry work where appearance is not a concern.

Building code

A set of regulations intended to ensure a minimum standard of health and safety in buildings.

Building enclosure

The parts of the building, principally its walls, roofs, and fenestration, that separate the interior of the building from the exterior, and that must effectively control the flow of heat, air, and moisture; also called the thermal envelope or the building envelope.

Building envelope

See Building enclosure.

Building felt

See Asphalt-saturated felt.

Building information modeling (BIM)

The digital, three-dimensional modeling of building systems, with the linking of model components to a ­database of properties and relationships.

Building-integrated photovoltaic (BIPV)

Conventional building materials laminated or coated with ­photovoltaic materials and interconnected into a ­power-­generating array.

Building paper

A water-resistive, ­asphalt-saturated paper used similarly to asphalt-saturated felt, to provide a ­protective layer in an exterior wall assembly.

Building separation joint

A plane along which a building is divided into separate structures that may move independently of one another.

Built-up roof (BUR)

A multi-ply roof membrane, made from layers of asphalt-saturated felt or other fabric, bonded together with bitumen.

Bull float

A long-handled tool used for the initial floating of a freshly poured concrete slab. See also Darby.

BUR

See Built-up roof.

Butt

The thicker end, such as the lower edge of a wood shingle or the lower end of a tree trunk; a joint between ­square-edged pieces; a weld between square-edged ­pieces of metal that lie in the same plane; a type of door hinge that attaches to the edge of the door.

Butt-joint glazing

A type of glass installation in which the vertical joints between lites of glass do not meet at a mullion, but are made weathertight with a sealant.

Button head

A smooth, convex bolt head with no provision for engaging a wrench.

Buttress

A structural device, usually of masonry or concrete, that resists the ­diagonal forces from an arch or vault.

Butyl rubber

A synthetic rubber compound.

C

CA

See Copper boron azole.

CAC

See Ceiling Attenuation Class.

CAD

See Computer-aided design.

Caisson

A cylindrical sitecast concrete foundation unit that penetrates through incompetent soil to rest upon an underlying stratum of rock or satisfactory soil; an enclosure that permits excavation work to be carried out underwater. Also called a drilled pier.

Calcined gypsum

Gypsum that has been ground to a fine powder and heated to drive off most of its water of hydration; used in the manufacture of gypsum board and as the principal ingredient in gypsum plasters; a nonhydraulic cementitious ­material; also called plaster of Paris.

Calcining

The driving off of the water of hydration from gypsum by the application of heat.

Camber

A slight, intentional initial ­curvature in a beam or slab.

Cambium

The thin layer beneath the bark of a tree that manufactures cells of wood and bark.

Cantilever

A beam, truss, or slab that extends beyond its last point of support.

Cant strip

A strip of material with a sloping face used to ease the transition from a horizontal to a vertical surface at the edge of a membrane roof.

Capillary action

The pulling of water through a small orifice or fibrous material by the attractive force between the water and the material.

Capillary break

A slot or groove intended to create an opening too large to be bridged by a drop of water and, thereby, to eliminate the passage of water by capillary action; the coarse aggregate layer under a concrete slab on grade which discourages the migration of water from the ground below into the concrete slab above.

Carbide-tipped tools

Drill bits, saws, and other tools with cutting edges made of an extremely hard alloy.

Carbonation

The process by which lime mortar reacts with atmospheric carbon dioxide to cure.

Carbon fiber reinforcing

In precast concrete, an open grid fabric of carbon fibers bonded with epoxy resin, used as a substitute for welded wire reinforcing.

Carbon steel

Low-carbon or mild steel.

Carbon steel bolt

A relatively low-strength bolt most often used for ­fastening minor steel framing elements or temporary connections.

Carpenter

One who makes things of wood.

Casement window

A window that pivots on an axis at or near a vertical edge of the sash.

Casing

The wood finish pieces surrounding the frame of a window or door; a cylindrical steel tube used to line a drilled or driven hole in foundation work.

Castellated beam

A steel wide-flange section whose web has been cut along a zigzag path and reassembled by welding in such a way as to create a deeper section.

Casting

Pouring a liquid material or slurry into a mold whose form it will take as it solidifies.

Casting bed

A permanent, fixed form in which precast concrete elements are produced.

Cast in place concrete

Concrete that is poured in its final location; sitecast concrete.

Cast iron

Iron with too high a carbon content to be classified as steel.

Cathode

The metal in a galvanic couple that experiences a decreased rate of corrosion.

Caulk

A low-range sealant.

Cavity drainage material

A material placed in the airspace of a cavity wall to catch mortar droppings and prevent clogging of weep holes at the bottom of the cavity.

Cavity wall

A masonry wall that includes a continuous airspace between its outermost wythe and the remainder of the wall.

CBA

See Copper boron azole.

CCA

See Chromated copper arsenate.

Cee

A metal framing member whose cross-sectional shape resembles the letter C.

Ceiling Attenuation Class (CAC)

An index of the ability of a ceiling construction to obstruct the passage of sound between rooms through the plenum.

Ceiling joist

See Joist.

Cellular decking

Panels made of steel sheets corrugated and welded together in such a way that hollow longitudinal cells are created within the panels.

Cellular raceway

A rectangular tube cast into a concrete floor slab for the purpose of housing electrical and communications wiring.

Cellulose

A complex polymeric carbohydrate of which the structural fibers in wood are composed.

Celsius

A temperature scale on which the freezing point of water is established as 0 and the boiling point as 100 degrees.

Cement

Generally, any substance used to adhere material together. In concrete, masonry, and plastering work, any of a number of inorganic materials that have cementing properties when combined with water. See also Cementitious ­materials.

Cementitious materials

In concrete, masonry, and plastering, inorganic materials that, when mixed with water, produce hardened products with adhesive and cohesive (cementing) properties; frequently used to refer exclusively to hydraulic cements (such as portland cement), to the exclusion of nonhydraulic (lime and gypsum) cements.

Cement–lime mortar

Mortar made from portland cement, hydrated lime, aggregate, and water, the most traditional formulation of modern masonry mortars. See also Masonry cement, Mortar cement.

Centering

Temporary formwork for an arch, dome, or vault.

Centering shims

Small blocks of synthetic rubber or plastic used to hold a sheet of glass in the center of its frame.

Ceramic tile

Small, flat, thin, fired clay tiles intended for use as wall and floor ­facings.

Chair

A device used to support reinforcing bars.

Chamfer

A flattening of a longitudinal edge of a solid member on a plane that lies at an angle of 45 degrees to the ­adjoining planes.

Channel

A steel or aluminum section shaped like a rectangular box with one side missing.

Chemically strengthened glass

Glass strengthened by immersion in a molten salt bath, causing an ion exchange at the surfaces of the glass that creates a prestress in a manner similar to heat-treated glass.

Chlorinated polyethylene (CPE)

A plastic material used in roof membranes.

Chlorosulfonated polyethylene (CSPE)

A plastic material used in roof membranes.

Chord

A top or bottom member of a truss.

Chromated copper arsenate (CCA)

A chemical used to protect wood against attack by decay and insects. Due to toxicity concerns, this chemical has been phased out of most treated wood used in residential and commercial building construction.

Chromogenic glass

Glass that can change its optical properties, such as thermochromic, photochromic, or electrochromic glass.

C-H stud

A steel wall framing member whose profile resembles a combination of the letters C and H; used to support gypsum panels in shaft walls.

Chuck

A device for holding a steel wire, rod, or cable securely in place by means of steel wedges in a tapering cylinder.

Churn drill

A steel tool used with an up-and-down motion to cut through rock at the bottom of a steel pipe caisson.

Cladding

A material used to cover the exterior of a building.

Clamp

A tool for holding two pieces of material together temporarily; unfired bricks piled in such a way that they can be fired without using a kiln.

Class A, B, C roofing

Roof covering materials classified according to their resistance to fire when tested in accordance with ASTM E108. Class A is the most resistant, and Class C is the least.

Clay

A fine-grained soil with plate-shaped particles, typically less than 0.0002 inch (0.005 mm) in size, whose properties are significantly influenced by the structural arrangements of the particles and the electrostatic forces acting between them.

Cleanout hole

An opening at the base of a masonry wall through which mortar droppings and other debris can be removed before the interior cavity of the wall is grouted.

Clear dimension, clear opening

The dimension between opposing inside faces of an opening.

Cleavage membrane

A resilient sheet placed underneath a finish tile assembly to prevent movement stresses in the underlying substrate from telegraphing into the finish assembly.

Climbing crane

A heavy-duty lifting machine that raises itself as the building rises.

Clinker

A fused, pebblelike mass that is an intermediate product of cement manufacture; a brick that is overburned.

Closer

The last masonry unit laid in a course; a partial masonry unit used at the corner of a header course to adjust the joint spacing; a mechanical device for regulating the closing action of a door.

CLSM

See Controlled low-strength ­material.

CLT

See Cross-laminated timber.

CMU

See Concrete masonry unit.

Coarse aggregate

Gravel or crushed stone in a concrete mix.

Coarse-grained soil

Soil with particles ranging in size from roughly 0.003 to 3 inches (0.075–75 mm); sands and gravels.

Code

See Building code.

Coefficient of Friction

A unitless measure of the resistance to slippage between two surfaces, either at rest (static coefficient of friction) or in motion (dynamic coefficient of friction) relative to each other. A higher value represents greater slip resistance. Used to describe the slip resistance of some finish flooring materials.

Cohesionless soil

See Frictional soil.

Cohesive soil

A soil such as clay whose particles are able to adhere to one another by means of cohesive and adhesive forces.

Cold-formed steel

Steel formed at a temperature at which it is no longer plastic, as by rolling or forging at room temperature.

Cold-rolled steel

Steel rolled to its final form at a temperature at which it is no longer plastic.

Cold-worked steel

See Cold-formed steel.

Collar joint

The vertical mortar joint between wythes of masonry.

Collar tie

A piece of wood nailed across two opposing rafters near the ridge to resist wind uplift.

Collated nails

Nails glued together in a strip for insertion into a nail gun.

Collector

A framing component that transfers lateral forces into parts of the structure designed to resist those forces.

Column

An upright structural member acting primarily in compression.

Column bar

See Vertical bar.

Column cage

An assembly of vertical reinforcing bars and ties for a concrete ­column.

Column-cover-and-spandrel system

A system of cladding in which panels of material cover the columns and spandrels, with horizontal strips of windows filling the remaining portion of the wall.

Column spiral

A continuous coil of steel reinforcing used to tie a concrete column.

Column tie

A single loop of steel bar, usually bent into a rectangular configuration, used to tie a concrete column.

Combination door

A door with interchangeable inserts of glass and insect screening, usually used as a second, exterior door and mounted in the same opening with a conventional door.

Commercial wrap

A synthetic sheet material, heavier than housewrap, with water-resistive and air-resistive properties used to provide a protective layer in an exterior wall assembly.

Common bolt

See Carbon steel bolt.

Common bond

Brickwork laid with five courses of stretchers followed by one course of headers.

Common nail

A standard-sized nail used for the fastening of rough framing members in wood light frame construction.

Common rafter

A roof rafter that runs parallel to the main slope of the roof. See also Hip rafter.

Composite

A material or assembly made up of two or more materials bonded together to act as a single unit.

Composite column

An upright structural member, acting primarily in compression, that is composed of concrete and a steel structural shape, usually a wide flange or a tube.

Composite construction

An assembly of differing materials, such as concrete and steel or concrete and wood, that once assembled is capable of performing as a unified structural unit.

Composite metal decking

Corrugated steel decking manufactured in such a way that it bonds securely to the concrete fill to form a reinforced concrete deck.

Composite wall

A masonry wall that incorporates two or more different types of masonry units, such as clay bricks and concrete blocks.

Composition shingle

See Asphalt shingle.

Compression

A squeezing force.

Compression gasket

A synthetic rubber strip that seals around a sheet of glass or a wall panel by being squeezed tightly against it.

Compressive strength

The ability of a material to withstand squeezing forces.

Computer-aided design (CAD)

The digital two-dimensional representation of building systems.

Concave joint

A mortar joint tooled into a curved, indented profile.

Concealed flashing

See Internal flashing.

Concealed grid

A suspended ceiling framework that is completely hidden by the tiles or panels it supports.

Concrete

A structural material produced by mixing predetermined amounts of cement, aggregates, and water and allowing this mixture to cure under controlled conditions.

Concrete block

A concrete masonry unit, usually hollow, that is larger than a brick.

Concrete masonry unit (CMU)

A block of hardened concrete, with or without hollow cores, designed to be laid in the same manner as a brick or stone; a ­concrete block.

Condensate

Water formed as a result of condensation.

Condensation

The process of changing from a gaseous to a liquid state, especially as applied to water.

Conduit

A steel or plastic tube through which electrical wiring is run.

Consolidate

In freshly poured concrete, to eliminate trapped air and cause the concrete to fill completely around the reinforcing bars and into all the corners of the formwork; usually done by vibrating the concrete.

Construction documents

The graphic construction drawings and written specifications to which a building is constructed.

Construction drawings

The graphic portion of the construction documents, usually produced by an architect or engineer, concerning the construction of a building.

Construction manager

An entity that assists the owner in the procurement of construction services.

Construction Type

In the International Building Code, any of five major systems of building construction that are differentiated by their relative resistance to fire.

Continuous ridge vent

See Ridge vent.

Contraction joint

See Control joint.

Contractor

A person or organization that undertakes a legal obligation to do construction work.

Control joint

An intentional, linear discontinuity in a structure or component designed to form a plane of weakness where cracking can occur in response to various forces so as to minimize or eliminate cracking elsewhere. Also called a contraction joint.

Controlled low-strength material (CLSM)

A concrete that is purposely formulated to have a very low but known strength, used primarily as a backfill material.

Convector

A heat exchange device that uses the heat in steam, hot water, or an electric resistance element to warm the air in a room; often called, inaccurately, a radiator.

Cool color

A coating applied to a roofing material that is nonwhite, yet reflects a relatively high percentage of the sun's thermal energy.

Cool roof

A roof covering that reflects a substantial portion of the sun's thermal energy.

Cope

The removal of a flange at the end of a steel beam in order to facilitate connection to another member; cutting of the end of a wood trim to match the profile of the piece with which it intersects.

Coped connection

A joint in which the end of one member is cut to match the profile of the other member.

Coping

A protective cap on the top of a masonry wall.

Coping saw

A handsaw with a thin, narrow blade, used for cutting detailed shapes in the ends of wood moldings and trim.

Copolymer

A large molecule composed of repeating patterns of two or more chemical units.

Copper

A soft, nonferrous metal, orange-red in original color, that oxidizes to a color ranging from blue-green to black.

Copper boron azole (CBA, CA)

A chemical used to preserve wood against attack by decay and insects.

Corbel

A spanning device in which masonry units in successive courses are cantilevered slightly over one another; a projecting bracket of masonry or concrete.

Coreboard

A thick gypsum panel used primarily in shaft walls.

Corner bead

A metal or plastic strip used to form a neat, durable edge at an outside corner of two walls of plaster or gypsum board.

Cornice

The exterior detail at the meeting of a wall and a roof overhang; a decorative molding at the intersection of a wall and a ceiling.

Corrosion

Oxidation, such as rust.

Corrosion inhibitor

A concrete, mortar, or plaster admixture intended to prevent oxidation of steel reinforcing bars.

Corrugated

Formed into a fluted or ribbed profile.

Counterflashing

A flashing turned down from above to overlap another flashing turned up from below so as to shed water.

Course

A horizontal layer of masonry units one unit high; a horizontal line of shingles or siding.

Coursed

In masonry, laid in courses with straight bed joints.

Cove base

A flexible strip of plastic or synthetic rubber used to finish the junction between resilient flooring and a wall.

Cover

In concrete, a specified thickness of concrete surrounding reinforcing bars to provide full embedment for the bars and protect them against fire and corrosion.

Coverboard

A material installed over low-slope roof insulation, to protect the insulation, provide a more stable substrate for the roof membrane, or increase the fire resistance of the roof assembly.

CPE

See Chlorinated polyethylene.

Cradle-to-gate analysis

A life-cycle analysis extending from original resource extraction only so far as when the material or product leaves its place of manufacture.

Cradle-to-grave analysis

See Life-cycle analysis.

Crawlspace

A space that is not tall enough to stand in, located beneath the bottom floor of a building.

Creep

A permanent inelastic deformation in a material due to changes in the material caused by the prolonged application of a structural stress; common in wood, concrete, and plastics.

Cripple stud

A wood wall framing member that is shorter than full-length studs because it is interrupted by a header or sill.

Critical path

The sequence of tasks that determines the least amount of time in which a construction project can be completed.

Cross-grain wood

Wood incorporated into a structure in such a way that the direction of its grain is perpendicular to the direction of the principal loads on the structure.

Cross-laminated timber (CLT)

Structural panels fabricated from solid lumber pieces, with members in each layer alternating in orientation from those above and below; used as structural floor, wall, and roof elements.

Crosslot bracing

Horizontal compression members running from one side of an excavation to the other, used to support sheeting.

Crown glass

Glass sheet formed by spinning an opened hollow globe of heated glass.

Cruck

A framing member cut from a bent tree so as to form one-half of a rigid frame.

CSPE

See Chlorosulfonated polyethylene.

Cup

A curl in the cross section of a board or timber caused by unequal shrinkage or expansion between one side of the board and the other.

Curing

The hardening of concrete, plaster, gunnable sealant, or other wet materials. Curing can occur through evaporation of water or a solvent, hydration, polymerization, or chemical reactions of various types, depending on the formulation of the material.

Curing compound

A liquid that, when sprayed on the surface of newly placed concrete, forms a water-resistant layer to prevent premature dehydration of the concrete.

Curtain wall

An exterior building wall that is supported by the frame of the building, rather than being self-­supporting or loadbearing.

Cylinder glass

Glass sheet produced by blowing a large, elongated glass cylinder, cutting off its ends, slitting it lengthwise, and opening it into a flat rectangle.

D

d

See Penny.

Damage weighted transmittance (Tdw)

The ratio of solar radiation that passes through a glazing unit to the amount of light striking the unit, weighted to account for the relative fading damage potential of the various wavelengths. The lower the damage weighted transmittance, the better the protection against fading afforded to interior fabrics and materials.

Damper

A flap to control or obstruct the flow of gases; specifically, a metal control flap in the throat of a fireplace or in an air duct.

Damping

The addition of energy-absorbing components into a structural building frame, to reduce lateral deflections and lessen the stresses imparted into the frame when subjected to high wind or seismic forces.

Dampproofing

A coating intended to resist the passage of water, commonly applied to the outside face of basement walls or to the inner face of a cavity in a masonry cavity wall.

Dap

A notch at the end of a piece of material.

Darby

A stiff straightedge of wood or metal used to level the surface of wet plaster or concrete.

Daylighting

Illuminating the interior of a building by natural means.

DCOF

See Dynamic coefficient of ­friction.

Dead load

Permanent loads on a ­building, including the weight of the building itself and any permanently ­attached equipment.

Decking

A material used to span across beams or joists to create a floor or roof surface.

Deep foundation

A building foundation that extends through upper strata of incompetent soil to reach deeper strata with greater bearing capacity.

Deformation

A change in the shape of a structure or structural element caused by a load or force acting on the structure.

Deformed reinforcing bar

Steel reinforcing bars with surface ribs for better bonding to concrete.

Demand-critical weld

A structural steel connection weld, essential to the stability of the structure during a seismic event and subject to special quality control and inspection procedures during construction.

Depressed strand

A pretensioning tendon that is pulled to the bottom of the beam at the center of the span to follow more closely the path of tensile forces in the member.

Derrick

Any of a number of devices for hoisting building materials on the end of a rope or cable.

Design/bid/build project delivery

A method of providing design and construction services in which the design and construction phases of the project are provided by different entities, usually used in combination with sequential construction.

Design/build project delivery

A method of providing design and construction services in which the design and construction phases of the project are provided by a single entity; frequently used in combination with fast track construction.

Dewatering

The extraction of water from an excavation or its surrounding soil.

Dew point

The temperature at which water will begin to condense from a mass of air with a given moisture content.

Diagonal bracing

See Bracing.

Diamond saw

A tool with a moving chain, belt, wire, straight blade, or circular blade whose cutting action is carried out by diamonds.

Diaphragm action

A bracing action that derives from the stiffness of a thin plane of material when it is loaded in a direction parallel to the plane. Diaphragms in buildings are typically floor, wall, or roof surfaces of plywood, reinforced masonry, steel decking, or reinforced concrete.

Die

An industrial tool for giving identical form to repeatedly produced or continuously generated units, such as a shaped orifice for giving form to a column of clay, a steel wire, or an aluminum extrusion; a shaped punch for making cutouts of sheet metal or paper; or a mold for casting plastic or metal.

Die-cut

Manufactured by punching from a sheet material.

Differential settlement

Subsidence of the various foundation elements of a building at differing rates.

Diffuser

A louver shaped so as to distribute air about a room.

Dimension lumber

Lengths of wood, rectangular in cross section, sawed directly from the log.

Dimension stone

Building stone cut to a rectangular shape.

Direct tension indicator washer

See Load indicator washer.

Distribution rib

A transverse beam at the midspan of a one-way concrete joist structure, used to allow the joists to share concentrated loads.

Divider strip

A strip of metal or plastic embedded in terrazzo to form control joints and decorative patterns.

Dome

An arch rotated about its vertical axis to produce a structure shaped like an inverted bowl; a form used to make one of the cavities in a concrete waffle slab.

Dormer

A structure protruding through the plane of a sloping roof, usually containing a window and having its own smaller roof.

Double glazing

Two parallel sheets of glass with an airspace between.

Double-hung window

A window with two overlapping sashes that slide vertically in tracks.

Double shear

Acting to resist shear forces at two locations, such as a bolt that passes through a steel supporting angle, a beam web, and another supporting angle.

Double-skin facade

An exterior wall system consisting of two separate glass skins separated by an interstitial space.

Double-strength glass

Glass that is approximately 1/8 inch (3 mm) thick.

Double tee

A precast concrete slab element that resembles the letters TT in cross section.

Dovetail slot anchor

A system for fastening to a concrete structure that uses metal tabs inserted into a slot that is small at the face of the concrete and larger behind.

Dowel

A short cylindrical rod of wood or steel; a steel reinforcing bar that projects from a foundation to tie it to a column or wall, or from one section of a concrete slab or wall to another.

Downspout

A vertical pipe for conducting water from a roof to a lower level; also called a leader.

Drag strut

A framing member or component acting as a collector to transfer lateral forces within the building frame; also called a drag tie.

Drainage

Removal of water.

Drainage fill

Crushed stone or gravel backfill materials with good drainage characteristics, placed around a foundation to facilitate drainage.

Draped tendon

A posttensioning strand placed along a curving profile that approximates the path of the tensile forces in a beam.

Drawing

Shaping a material by pulling it through an orifice, as in the drawing of steel wire or the drawing of a sheet of glass.

Drawings

See Construction drawings.

Drawn glass

Glass sheet pulled directly from a container of molten glass.

Drift

Lateral deflection of a building caused by wind or earthquake loads.

Drift pin

A tapered steel rod used to align bolt holes in steel connections during erection.

Drilled pier

See Caisson.

Drip

A discontinuity formed into the underside of a window sill or wall component to force adhering drops of water to fall free of the face of the building rather than to move farther toward the interior.

Dropchute

A flexible hoselike tube for placing concrete; used to break the fall of the concrete and prevent segregation.

Drop panel

A thickening of a two-way concrete structure at the head of a ­column.

Drying shrinkage

Shrinkage of concrete, mortar, or plaster that occurs as excess water evaporates from the material.

Dry-pack grout

A low-slump cementitious mixture tamped into the space in a connection between precast concrete members.

Dry-press process

A method of molding slightly damp clays and shales into bricks by forcing them into molds under high pressure.

Dry-set mortar

A tile-setting mortar formulated with portland cement, sand, and water retention compounds; used in thin-set tile applications.

“Dry” systems

Systems of construction that use little or no water during construction, as differentiated from systems such as masonry, plastering, and ceramic tile work.

Drywall

See Gypsum board.

Dry well

An underground pit filled with broken stone or other porous material from which rainwater from a roof drainage system can seep into the surrounding soil.

Duct

A hollow conduit, commonly of sheet metal, through which air can be circulated; a tube used to establish the position of a posttensioning tendon in a concrete structure.

DWV pipe

Drain–waste–vent pipe; the part of the plumbing system of a building that removes liquid wastes and conducts them to the sewer or sewage disposal ­system.

Dynamic coefficient of friction (DCOF)

The coefficient of friction, measured between two surfaces in motion relative to each other; used in some finish flooring slip resistance measurements. See also static coefficient of friction.

E

Earlywood

See Springwood.

Earth material

Rock or soil.

Eave

The horizontal edge at the low side of a sloping roof.

Edge bead

A strip of metal or plastic used to make a neat, durable edge where plaster or gypsum board abuts another material.

Edge spacer

The material used to separate lites of glass in an insulating glass unit; also called a spline.

Efflorescence

A light-colored, powdery deposit on the face of masonry or concrete, caused by the leaching of chemical salts from water migrating from within the structure to the surface.

EIFS

See Exterior insulation and finish system.

Elastic

Able to return to its original size and shape after removal of stress.

Elastomer

A rubber or synthetic rubber.

Elastomeric

Rubberlike. In low-slope roofing, a thermosetting membrane ­material.

Electrochromic glass

Glass that changes its optical properties in response to the application of electric current.

Electrode

A consumable steel wire or rod used to maintain an arc and furnish additional weld metal in electric arc ­welding.

Electrogalvanizing

A method of galvanizing, in which an electric current is used to deposit zinc from a liquid bath onto steel.

Elevation

A drawing that views a building from any of its sides; a vertical height above a reference point such as sea level.

Elongation

Stretching under load; growing longer because of temperature expansion.

Embodied carbon

The total carbon emissions associated with a material or product throughout its life cycle.

Embodied energy

The total energy consumption associated with a material or product throughout its life cycle.

Embodied water

The total freshwater consumption associated with a material or product throughout its life cycle.

EMC

See Equilibrium moisture content.

Enamel

A glossy or semigloss paint.

End dam

The turned-up end of a flashing that prevents water from running out of the end; a block inserted into the space within a horizontal aluminum mullion for the same purpose.

End nail

A nail driven through the side of one piece of lumber and into the end of another.

Energy recovery ventilator

A mechanical device that exhausts air from a building while recovering much of the sensible and latent heat from the exhausted air and transferring it to the incoming air.

Engineered fill

Earth compacted into place in such a way that it has predictable physical properties, based on laboratory tests and specified, supervised installation procedures.

Engineered lumber

See Structural composite lumber.

English bond

Brickwork laid with alternating courses, each consisting entirely of headers or stretchers.

Environmental label

Information or certifications used to describe the composition, environmental performance, or life-cycle impacts of a construction ­material or product.

EPDM

Ethylene propylene diene monomer, a synthetic rubber thermosetting material used in low-slope roofing membranes.

Equilibrium moisture content (EMC)

The moisture content at which wood stabilizes after a period of time in its destination environment.

Erector

The subcontractor who raises, connects, and plumbs up a building frame from fabricated steel or precast concrete components.

Ethylene propylene diene monomer

See EPDM.

Expanded metal lath

A thin sheet of metal that has been slit and stretched to transform it into a mesh; used as a base for the installation of plaster.

Expanded shale aggregate

A structural lightweight aggregate made from ground shale particles that have been heated to the point that moisture within the particles vaporizes, causing the particles to expand.

Expansion joint

A seam within a material or between materials that provides for material expansion and contraction.

Expansive soil

A clay soil that expands significantly with increased moisture ­content.

Exposed aggregate finish

A concrete surface in which the coarse aggregate is revealed.

Exposed grid

A framework for an acoustical ceiling that is visible from below after the ceiling is completed.

Extended-life admixture

A substance that retards the onset of the curing reaction in mortar so that the mortar may be used over a protracted period of time after mixing.

Extended set-control admixture

A substance that retards the onset of the curing reaction in concrete so that the material may be used over a protracted period of time after mixing.

Extensive green roof

A green roof with a relatively shallow soil, planted with low-maintenance, drought-tolerant plant ­materials.

Exterior insulation and finish system (EIFS)

A cladding system that consists of a thin layer of reinforced stucco applied directly to the surface of an insulating plastic foam board.

External flashing

In masonry, a flashing that is not concealed within the wall, usually at the roof level or top of the wall.

External gutter

A gutter hung off the edge of a roof, external to the roof construction itself.

Extrados

The convex surface of an arch.

Extrusion

The process of squeezing a material through a shaped orifice to produce a linear element with the desired cross section; an element produced by this process.

F

Fabricator

The company that prepares structural steel members for erection; any entity that assembles building components prior to arrival of the components on the construction site.

Facade

An exterior face of a building.

Face brick

A brick selected on the basis of appearance and durability for use in the exposed surface of a wall.

Face nail

A nail driven through the side of one wood member into the side of ­another.

Face-sealed wall

See Barrier wall.

Face shell

The portion of a hollow ­concrete masonry unit that forms the face of the wall.

Fahrenheit

A temperature scale on which the boiling point of water is fixed at 212 degrees and the freezing point at 32 degrees.

Fanlight

A semicircular or semielliptical window above an entrance door; often includes radiating muntins that resemble a fan.

Fascia

The exposed vertical face of an eave.

Fast track construction

A method of providing design and construction services in which design and construction overlap in time; also called phased construction.

Faying surface

The contacting surfaces of steel members joined with a slip-critical connection.

Felt

A thin, flexible sheet material made of fibers of paper, glass, or plastic pressed and bonded together.

Ferrous metal

Any iron-based metal.

Ferrous steel

In common usage, steel unprotected from corrosion by either galvanizing or alloying.

Fibrous reinforcing

Short fibers of glass, steel, or polypropylene mixed into concrete to act as either microfiber reinforcing or macrofiber reinforcing.

Fieldstone

Rough building stone gathered from river beds and fields.

Figure

The surface pattern of the grain of a piece of smoothly finished wood or stone.

Filigree precast concrete

A hybrid concrete system in which precast concrete sections are used as permanent formwork for cast-in-place concrete.

Fillet

A rounded inside intersection between two surfaces that meet at an angle.

Fillet weld

A weld at the inside intersection of two metal surfaces that meet at right angles.

Fine aggregate

Sand used in concrete, mortar, or plaster mixes.

Fine-grained soil

Soil with particles 0.003 inch (0.075 mm) or less in size; silts and clays.

Finger joint

A glued end connection between two pieces of wood, using an interlocking pattern of deeply cut “fingers.” A finger joint creates a large surface for the glue bond, to allow it to develop the full tensile strength of the wood it ­connects.

Finial

A slender ornament at the top of a roof or spire.

Finish

Exposed to view; material that is exposed to view.

Finish carpenter

One who does finish carpentry.

Finish carpentry

The wood components exposed to view on the building and usually assembled on site, such as window and door casings, baseboards, bookshelves, and the like; may also refer to exterior finish carpentry, such as exterior trim, deck railings, and similar items.

Finish coat

The final coat of a paint, plaster, or other finishing system.

Finish-coat plaster

The final coat of plaster, applied over gypsum base or one or more applications of base-coat plaster.

Finish floor

The floor material exposed to view, as differentiated from the subfloor, which is the loadbearing floor surface ­beneath.

Finish lime

A fine grade of quicklime used in finish-coat gypsum plasters and in ornamental plaster work; also called lime putty.

Finish nail

A relatively thin nail with a very small head; used for fastening trim and other finish woodwork items.

Fire area

In the International Building Code, an area within a building bounded by fire-resistant construction. Fire area size, occupant load, and location within the building are used to determine automatic sprinkler requirements.

Fire barrier

In the International Building Code, a fire-resistant wall intended to deter the spread of fire; used to separate exit stair enclosures, differing occupancies, and fire areas.

Fireblocking

Wood or other material used to partition concealed spaces within combustible framing; intended to restrict the spread of fire within such spaces.

Firebox

The part of a fireplace, stove, or furnace in which fuel is combusted.

Firebrick

A brick made to withstand very high temperatures, as in a fireplace, furnace, or industrial chimney.

Firecut

A sloping end cut on a wood beam or joist where it enters a masonry wall. The purpose of the firecut is to allow the wood member to rotate out of the wall without prying the wall apart if the floor or roof structure burns through in a fire.

Fire door

A fire-resistant door, used in fire resistance rated partitions and walls.

Fire partition

In the International Building Code, a fire-resistant wall intended to deter the spread of fire; used to separate tenant spaces, dwelling units, and corridors from surrounding areas of a building.

Fireproofing

Material used around steel or concrete structural elements to insulate them against excessive temperatures in case of fire.

Fire-protection rated glazing

Fire-rated glass for use in fire doors, fire windows, and other protected openings. See also Fire-resistance-rated glazing.

Fire-rated glass

Glass that is capable of retaining its integrity after being exposed to fire, either fire-protection rated glazing or fire-resistance-rated glazing.

Fire-resistance-rated glazing

Fire-rated glass capable of substituting in full for solid, fire-resistance-rated wall assemblies. Unlike fire-protection rated glazing, fire-resistance-rated glazing is not limited to use in doors, windows, and other openings.

Fire resistance rating

The time, in minutes or hours, that a material or assembly will resist fire exposure as determined by ASTM E119.

Firestopping

A component or mastic installed in an opening through a floor or around the edge of a floor to retard the passage of fire; frequently used interchangeably with fireblocking.

Fire wall

A wall extending from foundation to roof, required under a building code to separate buildings, or parts of buildings, as a deterrent to the spread of fire.

Fire zone

A legally designated area of a city in which construction must meet established standards of fire resistance and/or combustibility.

Firing

The process of converting dry clay into a ceramic material through the application of intense heat.

First cost

The cost of construction, not including operational costs.

Fixed window

Glass that is immovably mounted in a wall.

Flagstone

Flat stones used for paving or flooring.

Flame-spread rating

A measure of the rapidity with which fire will spread across the surface of a finish material as determined by ASTM standard E84.

Flange

A projecting crosspiece of a wide-flange or channel profile; a projecting fin.

Flash cove

A detail in which a sheet of resilient flooring is turned up at the edge and finished against the wall to create an integral baseboard.

Flashing

A thin, continuous sheet of metal, plastic, rubber, or waterproof paper used to prevent the passage of water through a joint in a wall, roof, or chimney.

Flat-grain lumber

See Plainsawn lumber.

Flat seam

A sheet metal roofing seam that is formed flat against the surface of the roof.

Flemish bond

Brickwork laid with each course consisting of alternating headers and stretchers.

Flitch

A collection of solid wood ­members or veneers, all cut from a single log.

Float

A small platform suspended on ropes from a steel building frame to permit ironworkers to work on a connection; a trowel with a slightly rough surface used in an intermediate stage of finishing a concrete slab; as a verb, to use a float for finishing concrete.

Float glass

Glass sheet manufactured by cooling a layer of molten glass on a bath of molten tin.

Floating floor

Wood or laminate flooring that is not fastened or adhered to the subfloor.

Floating foundation

A foundation placed at depth such that the weight of the soil removed is approximately equal to the weight of the building being supported.

Flood test

The submersion of a horizontal waterproofing system, usually for an extended period of time, to check for leaks.

Floor joist

See Joist.

Flue

A passage for smoke and combustion products from a furnace, stove, water heater, or fireplace.

Fluid-applied roof membrane

A roof membrane applied in one or more coats of a liquid that cure to form an impervious sheet.

Fluoropolymer

A highly stable organic compound used as a finish coating for building cladding.

Flush

Smooth, lying in a single plane.

Flush door

A door with smooth planar faces.

Flush glazing

See Structural glazing.

Flux

A material added to react chemically with impurities and remove them from molten metal. Fluxes are used both in steelmaking and in welding. Welding fluxes serve the additional purpose of shielding the molten weld metal from the air to reduce oxidation and other undesirable effects.

Fly ash

Dust collected in the stacks of coal-fired power plants, used as a supplementary cementitious material in concrete and mortar.

Flying formwork

Large sections of slab formwork that are moved by crane.

Fly rafter

A rafter in a rake overhang.

F-number

An index number expressing the statistical flatness or levelness of a concrete slab.

Foil-backed gypsum board

Gypsum board with aluminum foil laminated to its back surface to act as a vapor retarder and thermal insulator.

Folded plate

A roof structure whose strength and stiffness derive from a ­pleated or folded geometry.

Footing

The part of a foundation that spreads a load from the building across a broader area of soil.

Forced-air system

A furnace and/or cooling coil and ductwork that heat and/or cool air and deliver it, driven by a fan, to the rooms of a building.

Formaldehyde

An organic compound known to cause a range of adverse human health effects, traditionally used in the manufacture of wood product adhesives and binders. See also Phenol-­formaldehyde and Urea-formaldehyde.

Form deck

Thin, corrugated steel sheets that serve as permanent formwork for a reinforced concrete deck.

Form release compound

A substance applied to concrete formwork to prevent concrete from adhering.

Form tie

A steel or plastic rod with fasteners on either end, used to hold together the two surfaces of formwork for a concrete wall.

Form tie hole

A depression, ­typically conical in shape, in a cast-in-place ­concrete wall that remains after the protruding portions of a form tie are ­removed.

Formwork

Structures, usually temporary, that give shape to poured concrete and support it and keep it moist as it cures.

Foundation

The portion of a building that transmits structural loads from the building into the earth.

Framed connection

A shear connection between steel members made by means of steel angles or plates connecting to the web of the beam or girder.

Framing plan

A diagram showing the arrangement and sizes of the structural members in a floor or roof.

Framing square

An L-shaped measuring tool used by carpenters to lay out right-angle cuts as well as more complicated cuts, such as those required for stairs and sloping roof rafters.

Freestone

Fine-grained sedimentary rock that has no planes of cleavage or sedimentation along which it is likely to split.

Free water

In wood, water held within the cavities of the cells. See also Bound ­water.

Freeze protection admixture

A concrete or mortar additive, used to allow curing under conditions of low ambient temperature.

French door

A symmetrical pair of glazed doors hinged to the jambs of a single frame and meeting at the center of the opening.

Frictional soil

A soil, such as sand or gravel, that relies primarily on friction rather than attractive or repulsive forces between particles for its strength; also called a cohesionless soil.

Friction type connection

See Slip-critical connection.

Frit

Ground-up colored glass that is heat-fused to lites of glass to form functional or decorative patterns.

Frost line

The depth in the earth to which the soil can be expected to freeze during a severe winter.

Fully restrained moment connection

A steel frame moment connection sufficiently rigid such that the geometric angles between connected pieces remain unchanged during normal loading.

Furring channel

A sheet metal furring strip in the form of a cee-channel.

Furring strip

A length of wood or metal attached to a masonry or concrete wall to permit the attachment of finish materials using screws or nails; any linear material used to create a spatial separation between a finish material and an underlying substrate.

G

Gable

The triangular wall beneath the end of a gable roof.

Gable roof

A roof consisting of two oppositely sloping planes that intersect at a level ridge.

Gable vent

A screened, louvered opening in a gable, used for exhausting excess heat and humidity from an attic.

Gage

See Gauge.

Galling

Chafing or tearing of one ­material against another under extreme pressure.

Galvanic couple

A pair of metals with differing electrochemical potential, ­between which electrical current will flow if the metals are placed in a conducting medium.

Galvanic series

A list of metals in order of their relative electrochemical potential when immersed in a given conducting medium.

Galvanized steel

Steel with a zinc coating for the purpose of providing protection from corrosion.

Galvanizing

The application of a zinc coating to steel.

Gambrel

A roof shape consisting of two superimposed levels of gable roofs with the lower level at a steeper pitch than the upper.

Gantt chart

A graphic representation of a construction schedule, using a series of horizontal bars representing the duration of various tasks or groups of tasks that make up the project.

Gap graded soil

A soil graded so as to contain a broad range of particle sizes, but with certain sizes omitted.

Gasket

A dry, resilient material used to seal a joint between two rigid assemblies by being compressed between them.

Gauge

A measure of the thickness of sheet material. Lower gauge numbers signify thicker sheets; also spelled “gage.”

Gauged brick

A brick that has been rubbed on an abrasive stone to reduce it to a trapezoidal shape for use in an arch.

Gauging plaster

A gypsum plaster formulated for use in combination with finishing lime in finish coat plaster.

General contractor

A construction entity with responsibility for the overall conduct of a construction project.

Geotextile

A synthetic cloth used beneath the surface of the ground to stabilize soil or promote drainage.

GFRC

See Glass-fiber-reinforced concrete.

GFRP

See Glass-fiber-reinforced plastic.

Girder

A horizontal beam that supports other beams; a very large beam, especially one that is built up from smaller elements.

Girt

A horizontal beam that supports wall cladding between columns.

Glass block

A hollow masonry unit made of glass.

Glass fiber batt

A thick, fluffy, nonwoven insulating blanket of filaments spun from glass.

Glass-fiber-reinforced concrete (GFRC)

Concrete with a strengthening admixture of short, alkali-resistant glass fibers.

Glass-fiber-reinforced plastic (GFRP)

Plastic resin strengthened with embedded glass fibers, commonly referred to as “fiberglass.”

Glass mullion system

A method of constructing a large glazed area by stiffening the sheets of glass with perpendicular glass ribs.

Glaze

A glassy finish on a brick or tile; as a verb, to install glass.

Glazed structural clay tile

A hollow clay block with glazed faces, usually used for constructing interior partitions.

Glazier

One who installs glass.

Glazier's points

Small pieces of metal driven into a wood sash to hold glass in place.

Glazing

The act of installing glass; the transparent material (most often glass or plastic) in a glazed opening; as an adjective, referring to materials used in installing glass (for example, “glazing tape”).

Glazing compound

Any of several types of mastic used to bed small lites of glass in a frame.

Global warming potential

A material or product's life-cycle contribution to global warming, caused by greenhouse gas emissions.

Glue-laminated wood

A wood member made up of a large number of small strips of wood glued together.

Glulam

A shorthand expression for glue-laminated wood.

Grade

A classification of size or quality for an intended purpose; to classify as to size or quality.

Grade

The surface of the ground; to move earth for the purpose of bringing the surface of the ground to an intended level or profile.

Grade beam

A reinforced concrete foundation element that transmits the load from a bearing wall into spaced foundations such as pile caps or caissons.

Grain

In wood, the direction of the longitudinal axes of the wood fibers or the figure formed by the fibers. In stone, see Quarry bed.

Granite

Igneous rock with visible crystals of quartz and feldspar.

Green building

See Sustainability.

Green roof

A roof covered with soil and plant materials; also called a vegetated roof.

Groove weld

A weld made in a groove, created by beveling or milling the edges of the mating pieces of metal.

Ground

A strip attached to a wall or ceiling to establish the level to which plaster should be applied.

Grout

A high-slump mixture of portland cement, aggregates, and water, which can be poured or pumped into cavities in concrete or masonry for the purpose of embedding reinforcing bars and/or increasing the amount of loadbearing material in a wall; a specially formulated mortar-like material for filling under steel baseplates and around connections in precast concrete framing; a mortar used to fill joints between ceramic tiles or quarry tiles.

Gunnable sealant

A sealant material that is extruded in liquid or mastic form from a sealant gun.

Gusset plate

A flat steel plate used to connect the members of a truss; a stiffener plate.

Gutter

A horizontal or slightly sloped channel for the collection of rainwater and snowmelt at the eave of a roof.

GWB

Gypsum wallboard; see Gypsum board.

Gypsum

An abundant mineral; chemically, hydrous calcium sulfate.

Gypsum backing board

A lower-cost gypsum panel intended for use as an interior layer in multilayer constructions of gypsum board.

Gypsum board

An interior facing panel consisting of a gypsum core sandwiched between paper faces. Also called drywall, plasterboard.

Gypsum lath

Sheets of gypsum board manufactured specifically for use as a plaster base.

Gypsum plaster

Plaster whose cementing substance is calcined gypsum; used almost exclusively for interior finish plaster work.

Gypsum sheathing panel

A water-­resistant, gypsum-based sheet material used for exterior sheathing.

Gypsum wallboard (GWB)

See Gypsum board.

H

Hammerhead boom crane

A heavy-duty lifting device that uses a tower-mounted horizontal boom that may rotate only in a horizontal plane.

Hardboard

A very dense panel product, usually with at least one smooth face, made of highly compressed wood fibers.

Hardwood

Wood from deciduous (broadleaf) trees.

Hawk

A square piece of sheet metal with a perpendicular handle beneath, used by a plasterer to hold a small quantity of wet plaster and transfer it to a trowel for application to a wall or ceiling.

HDO

See High-density overlay.

Head

The horizontal top portion of a window or door.

Header

In framed construction, a member that carries other perpendicular framing members, such as a beam above an opening in a wall or a joist supporting other joists where they are interrupted by a floor opening. In steel construction, a beam that spans between girders. In masonry construction, a brick or other masonry unit that is laid across two wythes with its end exposed in the face of the wall.

Head jamb

See Head.

Head joint

The vertical layer of mortar between ends of masonry units.

Hearth

The noncombustible floor area outside a fireplace opening.

Heartwood

The dead wood cells in the center region of a tree trunk.

Heat-fuse

To join by softening or melting the edges with heat and pressing them together.

Heat of hydration

The thermal energy given off by concrete or gypsum as it cures.

Heat recovery ventilator

A mechanical device that exhausts air from a building while recovering much of the sensible heat from the exhausted air and transferring it to the incoming air. Also called an air-to-air heat exchanger. See also Energy recovery ventilator.

Heat-strengthened glass

Heat-treated glass that is not as strong as tempered glass, and that may not be used as safety glazing.

Heat-treated glass

Glass that is strengthened by a heat treatment process; either heat-strengthened glass or tempered glass.

Heaving

The forcing upward of ground or buildings by the action of frost or pile driving.

Heavy Timber construction

A type of wood construction made from large wood members and solid timber decking in a post-and-beam configuration; in the International Building Code, buildings of Type IV HT construction, consisting of heavy timber interior construction and noncombustible exterior walls, which are considered to have moderate fire-resistive properties.

High-density overlay (HDO)

A resin-treated overlay applied to plywood panels to achieve a smoother, more durable face.

High-lift grouting

A method of constructing a reinforced masonry wall in which the reinforcing bars are embedded in grout in story-high increments.

High-range sealant

A sealant that is capable of a high degree of elongation without rupture.

High-range water-reducing admixture

See Superplasticizer.

High-reactivity metakaolin

A white-colored natural pozzolan that enhances appearance, workability, and hardened properties of concrete.

High-strength bolt

A bolt designed to connect steel members by clamping them together with sufficient force that the load is transferred between them by ­friction.

High-volume fly ash concrete (HVFA concrete)

A concrete in which a high percentage of cementing substance is fly ash rather than portland cement.

Hip

The diagonal intersection of planes in a hip roof.

Hip rafter

A roof rafter at the intersection of two sloping roof planes. See also Common rafter.

Hip roof

A roof consisting of four sloping planes that intersect to form a pyramidal or elongated pyramid shape.

Hollow brick

Clay brick with up to 60 percent void area.

Hollow concrete masonry

Concrete masonry units that are manufactured with open cores, such as ordinary concrete blocks.

Hollow-core door

A door consisting of two face veneers separated by an airspace, with solid wood spacers around the four edges. The face veneers are usually connected by a grid of thin spacers within the airspace.

Hollow-core slab

A precast concrete slab element that has internal longitudinal cavities to reduce its self-weight.

Hollow structural section (HSS)

Hollow steel cylindrical or rectangular shapes used as structural members; also called structural tubing.

Hook

A semicircular bend in the end of a reinforcing bar, made for the purpose of anchoring the end of the bar securely into the surrounding concrete.

Hopper window

A window whose sash pivots on an axis along or near the sill and that opens by tilting toward the interior of the building.

Horizontal reinforcing

Steel reinforcing that runs horizontally in a masonry wall in the form of either welded grids of small-diameter metal rods or larger conventional reinforcing bars.

Hose stream test

A standard laboratory test to determine the relative ability of a building assembly to stand up to water from a fire hose after a specified period of fire testing.

Hot-dip galvanizing

A method of galvanizing in which a steel member or assembly is dipped into a bath of molten zinc.

Hot-rolled steel

Steel formed into its final shape by passing it between rollers while it is very hot and still in a plastic state.

Housewrap

A synthetic sheet material with water-resistive and air-resistive properties used as a substitute for asphalt-saturated felt or building paper to provide a protective layer in an exterior wall ­assembly.

HSS

See Hollow structural section.

HVFA concrete

See High-volume fly ash concrete.

Hydrated lime

Quicklime mixed with water, either in the factory or on the job site; an ingredient in masonry mortars, portland cement plaster, and gypsum plasters, to which materials it imparts properties such as workability, bulk, and smoothness; chemically, calcium hydroxide; also called slaked lime.

Hydration

The process by which cements combine chemically with water to harden.

Hydraulic cements

Cementitious materials, such as portland cement or blast furnace slag, that harden by reacting with water and whose hardened products are not water soluble. Nonhydraulic cements, such as lime, can also be mixed with pozzolans to create cements with hydraulic properties.

Hydronic heating system

A system that circulates warm water through convectors to heat a building.

Hydrostatic pressure

Pressure exerted by standing water.

Hygroscopic

Readily absorbing and retaining moisture.

Hyperbolic paraboloid shell

A concrete roof structure with a saddle shape.

I

IBC

See International Building Code and International Residential Code.

I-beam

Obsolete term; an American Standard section of hot-rolled steel, an archaic structural steel shape. (This term should not be applied to modern wide flange steel sections.)

Ice and water shield

See Rubberized underlayment.

Ice barrier

A sheet material, usually rubberized underlayment or sheet metal, applied to the lower portions of sloped roofs in cold climates to protect against ice dams.

Ice dam

An obstruction along the eave of a roof, caused by the refreezing of water emanating from melting snow on the roof surface above.

ICF

See Insulating concrete form.

Igneous rock

Rock formed by the solidification of magma.

IIC

See Impact Isolation Class.

I-joist

A manufactured wood framing member whose cross-sectional shape resembles the letter I.

Impact Isolation Class (IIC)

An index of the extent to which a floor assembly transmits impact noise from a room above to the room below.

Impact noise

Noise generated by footsteps or other impacts on a floor.

Impact wrench

A device for tightening bolts and nuts by means of rapidly repeated torque impulses produced by electrical or pneumatic energy.

Incising

Short, repetitive cuts made in the surface of a wood member to increase its absorption of treatment chemicals.

Ingot

A large block of cast metal.

Insulating concrete form (ICF)

A system of lightweight components, most commonly made of rigid polystyrene insulating foam, used as permanent formwork for the casting of concrete walls.

Insulating glass

A glazing unit made up of two or more sheets of glass with an airspace in between.

Insulating glass unit (IGU)

See Insulating glass.

Intensive green roof

A green roof with relatively deep soil capable of supporting a broad variety of plants and shrubs.

Internal drainage

Providing a curtain wall with hidden channels and weep holes to remove any water that may penetrate the exterior layers of the wall.

Internal flashing

In masonry, a flashing concealed with the masonry; also called a concealed or through-wall flashing.

Internal gutter

A gutter built into a roof assembly.

International Building Code (IBC) and International Residential Code (IRC)

The predominant U.S. model building codes.

Interstitial ceiling

A suspended ceiling with sufficient structural strength to support workers safely as they install and maintain mechanical and electrical installations above the ceiling.

Intrados

The concave surface of an arch.

Intumescent coating

A paint or mastic that expands to form a stable, insulating char when exposed to fire.

Inverted roof

A membrane roof assembly in which the thermal insulation lies above the membrane.

IRC

See International Building Code and International Residential Code.

Iron

In pure form, a metallic element. In common usage, ferrous alloys other than steels, including cast iron and wrought iron.

Iron dog

A heavy U-shaped staple used to tie the ends of heavy timbers together.

Ironworker

A skilled laborer who erects steel building frames or places reinforcing bars in concrete construction.

Isocyanurate foam

See Polyisocyanurate foam.

Isolation joint

A type of joint used to separate abutting materials or assemblies that should remain structurally independent, such as where new construction meets old, or where a nonstructural slab on grade abuts structural columns or walls.

J

Jack

A device for exerting a large force over a short distance, usually by means of screw action or hydraulic pressure.

Jack rafter

A shortened rafter that joins a hip or valley rafter.

Jack stud

A shortened stud that carries a header above a wall opening; also called a trimmer stud.

Jamb

The vertical side of a door or ­window.

Jet burner

A torch that burns fuel oil and compressed air, used in quarrying granite.

Joist

One of a parallel array of light, closely spaced beams used to support a floor deck (floor joist) or low-slope roof (ceiling joist).

Joist band

A broad, shallow concrete beam that supports one-way concrete joists whose depths are identical to its own.

Joist girder

A light steel truss used to support open-web steel joists.

Joist hanger

A sheet metal device used to create a structural connection where a joist is framed into a header or a ledger.

K

Keenes cement

A proprietary, dense, crack-resistant gypsum plaster formulation.

Key

A slot formed into a concrete surface for the purpose of interlocking with a subsequent pour of concrete; a slot at the edge of a precast member into which grout will be poured to lock it to an adjacent member; a mechanical interlocking of plaster with lath.

Kiln

A furnace for firing clay or glass products; a heated chamber for seasoning wood; a furnace for manufacturing quicklime, gypsum hemihydrate, or portland cement.

King stud

A full-length stud nailed alongside a jack stud.

Knee wall

A short wall under the slope of a roof.

Knot

A growth characteristic in wood, occurring where a branch joined the trunk of the tree from which the wood was sawed.

kPa

Kilopascal; a metric unit of pressure equal to 1 kilonewton per square meter.

L

Labyrinth

A cladding joint design in which a series of interlocking baffles prevents drops of water from penetrating the joint by momentum.

Lacquer

A coating that dries extremely quickly through evaporation of a volatile solvent.

Lagging

Planks placed between soldier beams to retain earth around an ­excavation.

Lag screw

A large-diameter wood screw with a square or hexagonal head.

Laminate

As a verb, to bond together in layers; as a noun, a material produced by bonding together layers of material.

Laminated glass

A glazing material consisting of outer layers of glass laminated to an inner layer of transparent plastic.

Laminated strand lumber (LSL)

Wood members made up of long shreds of wood fiber joined with a binder.

Laminated veneer lumber (LVL)

Structural composite lumber made up of thin wood veneers joined with glue.

Laminated wood

See Glue-laminated wood.

Landing

A platform in or at either end of a stair.

Lap joint

A connection in which one piece of material is placed partially over another piece before the two are fastened together.

Lateral force

A force acting generally in a horizontal direction, such as wind, earthquake, or soil pressure against a foundation wall.

Lateral thrust

The horizontal component of the force produced by an arch, dome, vault, or rigid frame.

Latewood

See Summerwood.

Latex caulk

A low-range sealant based on a synthetic latex.

Latex/polymer modified portland cement mortar

A tile-setting mortar similar to dry-set mortar, but with additives that improve the cured mortar's freeze-thaw resistance, flexibility, and adhesion; used for thin-set tile applications.

Lath

(rhymes with “math”) A base material to which plaster is applied.

Lathe

(rhymes with “bathe”) A machine in which a piece of material is rotated against a sharp cutting tool to produce a shape, all of whose cross sections are circles; a machine in which a log is rotated against a long knife to peel a continuous sheet of veneer.

Lather

(rhymes with “rather”) One who applies lath.

Lay-in panel

A finish ceiling panel that is installed merely by lowering it onto the top of the metal grid components of the ceiling.

Lead

(rhymes with “bed”) A soft, dull gray, easily formed nonferrous metal.

Lead

(rhymes with “bead”) In masonry work, a corner or wall end accurately constructed with the aid of a spirit level to serve as a guide for placing the bricks in the remainder of the wall.

Leader

(rhymes with “feeder”) See Downspout.

Leaf

The moving portion of a door.

Lean construction

Methods of construction and its management that emphasize efficiency, elimination of waste, and continuous improvement in quality.

Ledger

A horizontal wood member fastened to a wall or beam to which the ends of joists may be connected.

Lehr

A chamber in which glass is annealed.

Let-in bracing

Diagonal bracing that is nailed into notches cut in the face of the studs so as not to increase the thickness of the wall.

Level cut

A saw cut that produces a level surface in a sloping rafter when the rafter is in its final position. See also Plumb cut.

Leveling plate

A steel plate placed in grout on top of a concrete foundation to create a level bearing surface for the lower end of a steel column.

Lewis

A device for lifting a block of stone by means of friction exerted against the sides of a hole drilled in the top of the block.

Life-cycle analysis (LCA)

A comprehensive method of describing the environmental impacts of a material or product, accounting for all phases of its life from original resource extraction through final disposal or recycling; also called cradle-to-grave analysis.

Life-cycle cost

A cost that takes into account both the first cost and the costs of maintenance, replacement, fuel consumed, monetary inflation, and interest over the life of the object being evaluated.

Lift-slab construction

A method of building multistory sitecast concrete buildings by casting all the slabs in a stack on the ground, then lifting them up the columns with jacks and welding them in place.

Light

A sheet of glass, also spelled “lite.”

Light gauge steel stud

A length of thin sheet metal formed into a stiff shape and used as a wall framing member.

Light to solar gain (LSG) ratio

The visible light transmittance of a glazing unit divided by the solar heat gain coefficient, a measure of the energy-conserving potential of the unit.

Lightweight aggregate

Low-density aggregate used to make lightweight concrete, mortar, and plaster; in concrete, aggregate with a density of less than 70 lb/ft3 (1120 kg/m3).

Lignin

The natural cementing substance that binds together the cellulose in wood.

Lime

A nonhydraulic cementitious material, used as an ingredient in mortars and plasters. See also Hydrated lime, Quicklime.

Lime mortar

Masonry mortar made from a mix of lime, sand, and water; used principally in the restoration of historic structures.

Lime putty

See Finish lime.

Limestone

A sedimentary rock consisting of calcium carbonate, magnesium carbonate, or both.

Linear metal ceiling

A finish ceiling whose exposed face is made up of long, parallel elements of sheet metal.

Liner

A piece of marble doweled and cemented to the back of another sheet of marble.

Line wire

Wire stretched across wall studs as a base for the application of metal mesh and stucco.

Linoleum

A resilient floor covering material composed primarily of ground cork and linseed oil on a burlap or canvas backing.

Lintel

A beam that carries the load of a wall across a window or door opening.

Liquid limit

The moisture content at which a soil arrives at a flowable consistency; a relative indication of soil cohesiveness.

Liquid sealant

Gunnable sealant.

Lite

A sheet of glass, also spelled “light.”

Live load

Nonpermanent loads on a building caused by the weights of people, furnishings, machines, vehicles, and goods in or on the building.

Load

A weight or force acting on a structure.

Loadbearing

Supporting a superimposed weight or force.

Loadbearing wall

See Bearing wall.

Load indicator washer

A disk placed under the head or nut of a high-strength bolt to indicate sufficient tensioning of the bolt by means of the deformation of ridges on the surface of the disk; also called a direct tension indicator washer.

Lockpin and collar fastener

A boltlike device that is passed through holes in structural steel components, held in very high tension, and closed with a steel ring that is squeezed onto its protruding shank.

Lockstrip gasket

A synthetic rubber strip compressed around the edge of a piece of glass or a wall panel by inserting a spline (lockstrip) into a groove in the strip.

Longitudinal shrinkage

In wood, shrinkage along the length of the log.

Lookout

A short rafter, running perpendicular to the other rafters in the roof, which supports a rake overhang.

Louver

A construction of numerous sloping, closely spaced slats used to diffuse air or to prevent the entry of rainwater into a ventilating opening.

Low-e coating

See Low-emissivity ­coating.

Low-emissivity coating

A surface coating for glass that selectively reflects solar radiation of different wavelengths so as to allow high visible light transmittance while reflecting some or all types of infrared (heat) radiation. See also Low-e coating.

Low-lift grouting

A method of constructing a reinforced masonry wall in which the reinforcing bars are embedded in grout in increments not higher than 4 feet (1200 mm).

Low-range sealant

A sealant that is capable of a relatively slight degree of elongation prior to rupture; a caulk.

Low-slope roof

A roof that is pitched so near to horizontal that it must be made waterproof with a continuous membrane rather than shingles; commonly and inaccurately referred to as a “flat roof.” In the International Building Code, a roof with a slope of less than 2:12 (17 percent).

LSG

See Light to solar gain ratio.

LSL

See Laminated strand lumber.

Luffing-boom crane

A heavy-duty lifting device that uses a tower-mounted boom that may rotate in any vertical plane as well as in a horizontal plane.

LVL

See Laminated veneer lumber.

M

Machine grading

The grading of wood for its structural properties, performed by automated machinery, as distinct from visual grading.

Macrofiber reinforcing

In concrete, fibrous reinforcement capable of providing resistance to drying shrinkage and thermal stresses, and in some specialized concretes, also capable of acting as primary reinforcing. See also Microfiber reinforcing.

Mandrel

A stiff steel core placed inside the thin steel shell of a sitecast concrete pile to prevent it from collapsing during driving.

Mansard

A roof shape consisting of two superimposed levels of hip roofs with the lower level at a steeper pitch than the ­upper.

Manufactured home

A transportable house that is entirely factory built on a steel underframe supported by wheels; euphemistically referred to as a mobile home.

Marble

A metamorphic rock formed from limestone by heat and pressure.

Mason

One who builds with bricks, stones, or concrete masonry units; one who works with concrete.

Masonry

Brickwork, concrete blockwork, and stonework.

Masonry cement

A hydraulic cement made from a blend of portland cement, lime, and other dry admixtures designed to increase the workability of the mortar. See also Cement-lime mortar.

Masonry opening

The clear dimension required in a masonry wall for the installation of a specific window or door unit.

Masonry unit

A brick, stone, concrete block, glass block, or hollow clay tile intended to be laid in mortar.

Masonry veneer

A single wythe of masonry used as a facing over a frame of wood or metal.

MasterFormat

The trademarked title of a uniform indexing system for construction specifications, created by the Construction Specifications Institute and Construction Specifications Canada.

Mastic

A viscous, doughlike, adhesive substance; can be any of a large number of formulations for different purposes such as sealants, adhesives, glazing compounds, or roofing cements.

Mat foundation

A single concrete footing that is essentially equal in area to the area of ground covered by the building.

Maximum allowable slope

The steepest angle at which an excavation may be sloped so that the soil will not slide back into the hole. Also called angle of repose.

Medium-density fiberboard (MDF)

A fine-grained wood fiber and resin panel product.

Medium-density overlay (MDO)

A ­medium-weight, resin-treated overlay applied to plywood panels to achieve a smoother, more durable face.

Medium-range sealant

A sealant material that is capable of a moderate degree of elongation before rupture.

Meeting rail

The wood or metal bar along which one sash of a double-hung, single-hung, or sliding window seals against the other.

Member

An element of a structure such as a beam, girder, column, joist, piece of decking, stud, or component of a truss.

Membrane

A sheet material that may be used to control the passage of liquid water, water vapor, and/or air.

Membrane fire protection

A ceiling used to provide fire protection to the structural members above.

Metal decking

Corrugated metal sheets used as the structural base for floors (“floor decking”) and roofs (“roof decking”) in steel frame construction. See also Cellular decking and Composite metal decking.

Metal lath

A steel mesh used primarily as a base for the application of plaster.

Metallic-coated steel

Steel sheet coated with zinc or zinc-aluminum for improved corrosion resistance.

Metamorphic rock

A rock created by the action of heat or pressure on a sedimentary rock or soil.

Microfiber reinforcing

In concrete, fibrous reinforcement against plastic shrinkage cracking. See also Macrofiber reinforcing.

Microsilica

See Silica fume.

Middle strip

The half-span-wide zone of a two-way concrete slab that lies midway between columns.

Mild steel

Ordinary structural steel, containing less than three-tenths of 1 percent carbon.

Mill construction

The traditional name for a construction type consisting of exterior masonry bearing walls and an interior framework of heavy timbers and solid timber decking; also called slow-burn construction. See also Heavy Timber construction.

Milling

Shaping or planing by using a rotating cutting tool.

Millwork

Wood interior finish components of a building, including moldings, windows, doors, cabinets, stairs, mantels, and the like.

Minimum critical radiant flux exposure

A measure of a material's resistance to ignition by the radiant heat of fire and hot gasses in adjacent spaces, usually applied to flooring materials.

Miter

A diagonal cut at the end of a piece; the joint produced by joining two diagonally cut pieces at right angles.

Mobile home

See Manufactured home.

Model building code

A code that is offered by a recognized national organization as worthy of adoption by state or local governments.

Modified bitumen

A natural bitumen with admixtures of synthetic compounds to enhance such properties as flexibility, plasticity, and durability.

Modified bitumen roof membrane

A multi-ply bituminous roof membrane made from plies of factory-manufactured modified bitumen sheets.

Modular

Conforming to a multiple of a fixed dimension.

Modular green roof

A green roof system in which all components are provided in self-contained, easily transported and installed trays or modules.

Modular home

A house assembled on the site from boxlike factory-built sections.

Modulus of elasticity

An index of the stiffness of a material, derived by measuring the elastic deformation of the material as it is placed under stress and then dividing the stress by the deformation.

Moisture barrier

A membrane used to resist the migration of liquid water through a floor, wall, or roof.

Molding

A strip of wood, plastic, or plaster with an ornamental profile.

Molding plaster

A fast-setting gypsum plaster used for the manufacture of cast ornament.

Moment

A force acting at a distance from a point in a structure so as to cause a tendency of the structure to rotate about that point. See also Bending moment, Moment connection.

Moment connection

A connection between two structural members that is resistant to rotation between the members and therefore capable of transmitting bending moments between the connected members, as differentiated from a shear connection, which allows (slight) rotation. See also Fully restrained moment connection, Partially restrained moment connection, and Simple connection.

Moment-resisting frame

A structural building frame that is strengthened to resist lateral forces with moment connections between beams and columns.

Momentum

The tendency of a moving body to continue to move in the same direction unless acted on by an outside force.

Monolithic

Of a single massive piece.

Monolithic terrazzo

A thin terrazzo topping applied to a concrete slab without an underbed.

Mortar

A substance used to join masonry units, consisting of cementitious materials, fine aggregate, and water. See also Cement-lime mortar, Lime mortar.

Mortar bed tile

See Thickset tile.

Mortar cement

In masonry, a blend of portland cement, lime, and other ­additives, that produces mortar comparable in its bond strength properties to ­cement-lime mortar. See also Cement-lime mortar.

Mortise and tenon

A joint in which a tonguelike protrusion (tenon) on the end of one piece is tightly fitted into a rectangular slot (mortise) in the side of the other piece.

Movement joint

A line or plane along which movement is allowed to take place in a building or a surface of a building in response to such forces as moisture ­expansion and contraction, thermal ­expansion and contraction, foundation settling, and seismic forces.

MPa

Megapascal; a unit of pressure equal to 1 meganewton per square meter.

Mud set tile

See Thickset tile.

Mud slab

A slab of weak concrete placed directly on the ground to provide a (usually temporary) working surface that is hard, level, and dry.

Mullion

A vertical or horizontal bar between adjacent window or door units; a framing member in a metal-and-glass curtain wall.

Muntin

A small vertical or horizontal bar between small lites of glass in a sash.

Muriatic acid

Hydrochloric acid.

Mushroom capital

A flaring conical head on a concrete column.