Glossary


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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

TermDefinition
Abrasion ResistanceResistance to being worn away by rubbing or friction.
AbsorptionThe process by which a liquid or mixture of liquid and gases is drawn into the pores of a porous solid material.
AbsporptivityThe relative ability to absorb sound and light.
Abutment JointA surface divider joint designed to allow free movement between new and existing construction or between different materials.
AcceleratorA substance, such as calcium chloride, added to a concrete mix to speed up its setting and strength development.
Access FlooringA raised finish floor surface consisting entirely of small, individually removable panels beneath which wiring, ductwork, and other services may be installed.
Access RightRight of an owner to have ingress and egress to and from a property.
Accessory BuildingA building or structure on the same lot as the main or principal building.
Acoustical CeilingA ceiling of fibrous tiles that are highly absorbent of sound energy.
Acoustical GlassA glazing unit used to reduce the transmission of sound through the glazed opening by bonding a soft interlayer between the layers of glass.
Acoustical PlasterCalcined gypsum mixed with lightweight aggregates.
AcousticsScience dealing with the production, control, transmission, reception and effects of sound, and the process of hearing.
AcrylicA transparent thermoplastic made from esters of acrylic acid.
Active PressureThe pressure exerted by retained earth against a retaining wall.
AdditiveMaterials mixed with a basic plastic resin to alter its properties.
AdhesionThe ability of a coating to stick to another surface.
AdhesiveA substance used to hold materials together by surface attachment.
AdmixtureA prepared substance added to concrete to alter or achieve certain characteristics.
AdsorbantA material that has the ability to cause molecules of gases, liquids, or solids to adhere to its surfaces without changing the adsorbent physically or chemically.
AestheticsThe sudy or theory of beauty.
AgglomerationA process that bonds ground iron-ore particles into pellets to facilitate handling.
AggregateSand, gravel, crushed stone or other material that is a main constituent of Portland Cement, concrete and aggregated gypsum plaster. Also, polystyrene, perlite and vermiculite particles used in texture finishes.
AIA(1) The American Institute of Architects. Founded in 1857 and headquartered in Washington DC, the AIA offers resources for architects and is an advocate for the value of architecture.Architects also use the AIA designation to indicate that they are both members of The American Institute of Architects and licensed to practice the profession.(2) American Insurance Assn., successor to the National Board of Fire Underwriters and a nonprofit organization of insurance companies.
Air EntrainmentThe incorporation of tiny air bubbles into concrete or mortar to improve its workability and resistance to freezing.
Air GapIn plumbing, an unobstructed vertical distance between the lowest opening of any pipe that supplies a plumbing fixture and the level at which the fixture will overflow.
Air-ConditioningThe process of treating air to control simultaneously its humidity, cleanliness, and temperature and to provide distribution within a building.
Air-Dried LumberWood dried by exposing it to air.
Air-Entrained CementA Portland cement with an admixture that causes a controlled quantity of stable, microscopic air bubbles to form in the concrete.
Air-Entrained ConcreteConcrete with an admixture added that produces millions of microscopic air bubbles in the concrete.
Air-Supported StructureA membrane enclosing a pressurized occupied space, which must be held down to its foundation.
Airborne SoundSound traveling through the medium of air.
AlkydSynthetic resin modified with oil for good adhesion, gloss, color retention, and flexibility.
Allowable StressThe maximum unit stress permissible in a structural member. Also referred to as working stress.
AlloyA metallic material composed of two or more chemical elements one of which is a metal.
Aloying ElementAmu substance added to a molten metal to change its mechanical or physical properties.
Alternating CurrentAn electric current that varies periodically in value and direction by flowing first in one direction and then in the opposite direction.
AltitudeThe angle that the sun makes with the horizon.
AluminaA hydrated form of aluminum oxide from which aluminum is made.
Ambient TemperatureThe temperature of the surrounding air.
AmpereA basic SI unit that measures the rate of flow of electric current.
Anaerobic Bonding AgentsBonding agents that set hard when not exposed to oxygen.
AnchorMetal securing device embedded or driven into masonry, concrete, steel or wood.
Anchor BoltHeavy, threaded bolt embedded in the foundation to secure sill to foundation wall or bottom plate of exterior wall to concrete floor slab.
Angle of ReposeThe angle of the sloped surface of the sides of an excavation.
AnnealingHeating a metal to a high temperature followed by controlled cooling to relieve internal stresses.
Annular Ring NailA deformed shank nail with improved holding qualities specially designed for use with gypsum board.
AnodizingAm electrolytic process that forms a permanent, protective oxide coating on aluminum.
ANSIAmerican National Standards Institute, a nonprofit, national technical association that publishes standards covering definitions, test methods, recommended practices and specifications of materials. Formerly American Standards Assn. (ASA) and United States of America Standards Institute (USASI).
APA Performance-Rated PanelsPlywood manufactured to the structural specifications and standards of APA – The Engineered Wood Association.
AquiferAn underground permeable material through which water flows.
Arc ResistanceThe total elapsed time in seconds and electric current must arc to cause a part to fail.
ArchA curved structure in which the internal stresses are essentially compression.
Architectural Terra CottaClay masonry units made with a textured or sculptured face.
Area Separation WallResidential fire walls, usually with a 2- to 4-hour rating, designed to prevent spread of fire from an adjoining occupancy; extends from foundationGlossFoundation.1041 to or through the roof. Identified by codes as either “fire wall”, “party wall” or “townhouse separation wall.”
ASAFormerly American Standards Assn., now American National Standards Institute (ANSI).
AsphaltDark brown to black hydro-carbon solids or semisolids having bituminous constituents that gradually liquify when heated.
ASTMFormerly American Society for Testing and Materials, now ASTM, a nonprofit, national technical society that publishes definitions, standards, test methods, recommended installation practices and specifications for materials.
AttenuationReduction in sound level.
AutoclaveA high-pressure steam room that rapidly cures green concrete units.
Awning WindowA window that pivots near the top edge of the sash and projects toward the exterior.
Axial LoadA longitudinal load that acts at the centroid of a member and perpendicular to it’s cross section.
Axminster ConstructionCarpet formed by weaving on a loom that inserts each tuft of pile individually into the backing.
AzimuthA horizontal angle measured clockwise from North or South.
Back BlockingA short piece of gypsum board adhesively laminated behind the joints between each framing member to reinforce the joint.
BackfillEarth filled in around a foundation wall to replace earth removed for construction of the foundation.
Backup StripsPieces of wood nailed at the ceiling-sidewall corner to provide fastening for ends of plaster base or gypsum panels.
BallastAn electrical device to provide the starting voltage and operating current for fluorescent, mercury, and other electric discharge lamps.
Balloon FrameMethod of framing outside walls in which studs extend the full length or height of the wall.
Bank MeasureThe volume of soil in situ in cubic yards.
Bar JoistOpen-web, flat truss structural member used to support floor or roof structure. Web section is made from bar or rod stock, and chords are usually fabricated from “T” or angle sections.
Barrier-FreeThe absense of environmental barriers, permitting free access and circulation by the handicapped.
BatchThe amount of concrete mixed at one time.
BattenNarrow strip of wood, plastic, metal or gypsum board used to conceal an open joint.
BauxiteOre containing high percentages of aluminum oxide.
BCMCBoard for the Coordination of Model Codes; part of the Council of American Building Officials Association (CABO).
BeamA straight horizontal structural loadbearing member spanning a distance between supports.
BearingSupport area upon which something rests, such as the point on bearing walls where the weight of the floor joist or roof rafter bears.
Bearing CapacityThe ability of a soil to support load.
Bearing PileA pile that carries a vertical load.
Bearing PlateA steel plate placed under a beam, column, or truss to distribute the end reaction from the beam to the supporting member.
Bearing WallA wall that supports any vertical load in addition to it’s own weight.
BedTo set firmly and permanently in place.
BedrockThe hard, solid rock formation at or below the surface of the earth.
Bench MarkA relatively permanent point of known location and elevation.
BendingBowing of a member that results when a load or loads are applied laterally between supports.
Bending MomentThe algebraic sum of the moments of all forces that are on one side of a give cross-section of a beam.
Bending StressA compressive or tensile stress developed by applying non-axial force to structural members.
BeneficationA process of grinding and concentration that removes unwanted elements from iron-ore before the ore is used to produce steel.
Bentonite ClayAn absorptive clay that swells several times its dry volume when saturated with water.
BermA convex shapeed bank of earth.
BinderFilm-forming ingredient in paint that binds the suspended pigment particles together.
BitumenA generic term describing a material that is a mixture of predominantly hydrocarbons in solid or viscous form. It is derived from coal and petroleum.
Bitumenous CoatingCoating formulated by dissolving natural bitumens in an organic solvent.
BleedingExcess water that rises to the surface of concrete shortly after it has been poured.
BlockingWood pieces inserted between joists, studs, rafters, and other structural members to stabilize the frame, provide a nailing surface for finish materials, and block the passage of fire between the members.
Board Foot (Bd. Ft.)Volume of a piece of wood, nominal 19 x 129 x 18. All lumber is sold by the board-foot measure.
BoardsLumber less than 2 inches (50.8 mm) thick and 1 inch (25.4 mm) or greater in width.
BoilerA closed vessel used to produce hot water or steam.
Bond BeamA continuous reinforced beam formed from horizontal masonry members bonded with reinforced concrete.
Bond BreakerA material used to prevent adjoining materials from adhering.
Bonding AgentA compound that will hold materials together by bonding to the surfaces to be joined.
BoundaryThe legal recorded property line between two parcels of land.
Box BeamA structural member of metal or plywood whose cross-section is a closed rectangular box shape.
Box SillA type of sill used in frame construction in which the floor joists butt and are nailed to a header joist and rest on the sill.
Braced FrameA vertical truss used to resist lateral forces.
BranchA pipe in a plumbing system into which no other branch pipes discharge and that discharges into a main or submain.
Branch CircuitThe electrical wiring between the overcurrent protection device and the connected outlets.
Branch IntervalA length of soil or waste stack 8 feet or more in height (equal to one story) within which the horizontal branches from one floor or story of a building are connected to a stack.
Branch VentA vent connecting one or more individual vents into a vent stack or stack vent.
Branch, PlumbingA horizontal run of waste piping that carries waste material to a vertical riser.
Breaking StrengthThe point at which a material actually begins to break.
Brick VeneerNon-loadbearing brick facing applied to a wall to give appearance of solid-brick construction; bricks are fastened to backup structure with metal ties embedded in mortar joints.
BridgingMembers attached between floor joists to distribute concentrated loads over more than one joist and to prevent rotation of the joist. Solid bridging consists of joist-depth lumber installed perpendicular to and between the joists. Cross-bridging consists of pairs of braces set in an “X” form between joists.
Brinell HardnessA measure of the resistance of a material to indentation.
Brinnel Hardness NumberA measure of Brinell hardness that is obtained by dividing the load in kilograms by the area of the indentation given in square millimeters.
British Thermal Unit (BTU)The amount of heat required to raise the temperature of 1 pound (lb) of water by 1 degree Fahrenheit (F).
BrittlenessThe characteristic of a material that tends to crack or break without appreciable plastic deformation.
Brown CoatThe second coat of plaster in a three-coat plaster finish.
Buffer ZoneAn area separating two different elements or functions.
Buffer, ElevatorEnergy-absorbing units placed in the elevator pit.
Buildable AreaThe net ground area of a lot that can be covered by a building after required setbacks and other zoning limitations have been accounted for.
Building CodeA set of legal regulations that ensure a minimum standard of health and safety in buildings.
Building DrainThe lowest horizontal piping of a plumbing drainage system that receives the discharge from soil, waste, and other drainage pipes within the building and carries the wasted to the building sewer.
Building EnvelopeThe enclosure that contains a building’s maximum volume.
Building LineA defined limit within a property line beyond which a structure may not protrude.
Building SewerHorizontal piping that carries the waste discharge from the building drain to the public sewer or septic tank.
Built-Up Roof MembraneA continuous, semi-flexible roof membrane built up fo plies of saturated felts, coated felts, fabrics, or mats that have surface coats of bitumens. The last ply is covered with mineral aggregates, bituminous materials, or a granular-surface roofing sheet.
BurningCuring bricks by placing them in a kiln and subjecting them to a high temperature.
BusA rigid electric conductor enclosed in a protective busway.
BuswayA rigid conduit used to protect a bus running through it.
BX CableA cable sheathed with spirally wrapped metal strip identified as Type AC.
Cable TrayA ladderlike metal frame, open on the top, used to support insulated electrical cables.
CABOCouncil of American Building Officials Association, made up of representatives from three model codes. Issues National Research Board (NRB) research reports.
CaissonA watertight structure within which work can be carried out below the surface of water.
Calcareous ClaysClays containing at least 15 percent calcium carbonate.
Calcined GypsumGround gypsum that has been heated to drive off the water content.
CamberCurvature built into a beam or truss to compensate for loads that will be encountered when in place and load is applied. The crown is placed upward. Insufficient camber results in unwanted deflection when the member is loaded.
CandelaA metric unit of luminous intensity that closely approximates candlepower.
CandlepowerA term used to express the luminous intensity of a light source. It is the same magnitude as a candela.
Cant BeamBeam with edges chamfered or beveled.
Cant StripTriangular section laid at the intersection of two surfaces to ease or eliminate effect of a sharp angle or projection.
Capillary ActionThe movement of a liquid through small openings of fibrous material by the adhesive force between the liquid and the material.
Capillary BreakA groove in a member used to create an opening that is too wide to be bridged by a drop of water, thus eliminating the passage of water by capillary action.
Car Safeties, ElevatorDevices used to stop a car and hold it in position should it travel at an excessive speed or go into a free fall.
Car, ElevatorThe load-carrying unit of an elevator, consisting of a platform, walls, ceiling, door, and a structural frame.
Carbon SteelAny steel for which no minimum content for alloying agents is specified, but for which the carbon content is the element used to determine its properties.
Carrying ChannelMain supporting member of a suspended ceiling system to which furring members or channels attach.
CasementGlazed sash or frame hung to open like a door.
CasingThe trim around windows, doors, columns or piers.
Cast IronA hard, brittle metal made of iron that contains a high percentage of carbon.
Cast-In-Place ConcreteConcrete members formed and poured on the building site in the locations where they are needed.
Cast-In-Place PilesConcrete piles cast in a hollow metal shell driven into the earth or an uncased hole.
CastingA metal part produced by pouring a molten metal into a mold.
Catch BasinA drainage device used to collect water, with a deep pit to catch sediment.
CaulkingA resilient material used to seal cracks and prevent leakage of water.
Cavity WallA masonry wall made up of two wythes of masonry units separated by an air space.
CementA material that is able to unite nonadhesive materials into a solid mass.
Cement BoardA factory-manufactured panel, 1/4″ to 3/4″ thick, 32″ to 48″ wide, and 3′ to 10′ long, made from aggregated and reinforced portland cement.
Cement-Lime MortarMortar made with the addition of slaked lime to the cement.
Cementitious MaterialsMaterials that have cementing properties.
Central Service CoreA fire-resistant vertical shaft through a multistory building used to route electrical, mechanical, and transportation systems.
CentroidThe point in a cross-section where all of the area may be considered concentrated without affecting the moment of the area about any axis.
CeramicA class of products made of clay fired at high temperatures.
Ceramic GlazeA compound of metallic oxides, chemicals, and clays fused to a material at high temperature, providing a hard, smooth surface.
Chalk LineStraight working line made by snapping a chalked cord stretched between two points, transferring chalk to work surface.
ChaseA recessed area in a wall for holding pipes and conduit that passes vertically between floors.
Chemical StrengtheningA process for strengthening glass that involves immersing the glass in a molten salt bath.
ChillerA refrigerating machine composed of a compressor, a condenser, and an evaporator, used to transfer heat from one fluid to another.
Chord, BottomA horizontal or inclined structural member forming the lower edge of a truss.
Chord, TopA horizontal or inclined structural member forming the top edge of a truss.
Circuit BreakerAn electrical device used to open and close a circuit by nonautomatic means or to open a circuit by automatic means at a predetermined overcurrent without damage to itself.
CirculationThe flow or movement of people, goods, vehicles, etc., from place to place.
CladdingA nonload-bearing exterior wall enclosing a building. It may be brick, aluminum, steel, bronze, plastic, glass, stone, or other acceptable material.
Class A,B,C RoofingClassification of roofing materials by their resistance to fire when tested in accordance with ASTM E108.
ClayA very cohesive material made up of microscopic particles (less than 0.00008 inches or 0.002 mm).
Clay TileA unit made from fired and sometimes glazed clay and used as a finish surface on floors and walls.
CleanoutsOpenings in the waste piping system that permit cleaning obstructions from the pipe.
Clear CoatingA transparent protective and/or decorative film.
Clear SpanThe horizontal distance between the interior edges of supporting members.
Coal TarTar produced through the destructive distillation of coal during the conversion of coal to coke.
Coal Tar PitchA dark brown to almost black hydrocarbon material derived by distilling coke-oven tar.
CoatingA paint, varnish, lacquer, or other finish used to create a protective and/or decorative layer.
Coefficient of Heat Transmission (U)Total amount of heat that passes through an assembly of materials, including air spaces and surface air films. Expressed in Btu per hr., per sq. ft., per °F temperature difference between inside and outside air (beyond the surface air films). “U” values are often used to represent wall and ceiling assemblies, floors and windows. Note: “k” and “C” values cannot simply be added to obtain “U” values. “U” can only be obtained by adding the thermal resistance (reciprocal of “C”) of individual items and dividing the total into 1.
Coefficient of Hygrometric ExpansionSee Hygrometric Expansion.
Coefficient of RunoffA fixed ratio of total rainfall that runs off a surface.
Coefficient of Thermal Conductance (C)Amount of heat (in Btu) that passes through a specific thickness of a material (either homogeneous or heterogeneous) per hr., per sq. ft., per °F. Measured as temperature difference between surfaces. The “C” value of a homogeneous material equals the “k” value divided by the material thickness: C = k/t (where t = thickness of material in inches)It is impractical to determine a “k” value for some materials such as building paper or those only used or formed as a thin membrane, so only “C” values are given for them.
Coefficient of Thermal Conductivity (k)Convenient factor represents the amount of heat (in Btu) that passes by conduction through a one inch thickness of homogeneous material, per hr., per sq. ft., per °F. Measured as temperature difference between the two surfaces of the material.
Coefficient of Thermal ExpansionSee Thermal Expansion.
CofferdamA temporary watertight enclosure around an area of water-bearing soil or an area of water from which water is pumped allowing construction to take place in the water-free area.
Cogeneration SystemsSystems using fossil fuel, geothermal energy, wind, or solar energy to produce electricity and heat.
CohesionThe molecular forces between particles within a body which acts to unite them.
Cohesionless SoilA soil that when unconfined has little or no cohesion when submerged and no significant strength when air dried.
Cohesive SoilA soil that when unconfined has considerable cohesion when submerged and considerable strength when air dried.
Cold-Rolled SteelSteel rolled to the final desired shape at a temperature at which it is no longer plastic.
Collector StreetA street into which minor streets empty and which leads to a major arterial.
ColumnVertical loadbearing member.
Combined SewerSewer that carries both storm water and sanitary or industrial wastes.
Comfort ZoneAny combination of temperature and himidity in which the average person feels comfortable.
CompactionCompressing soil to increase its density.
CompartmentA small area within a larger area enclosed by partitions.
Composite MaterialsMaterials made by combining several layers of different materials.
Composite PanelsPanels having a reconstituted wood core bonded between layers of solid veneer.
CompressionThe conditions of being shortened (compressed) by force.
Compression TestA test used to determine the behavior of materials under compression.
Compressive StrengthMeasures maximum unit resistance of a material to crushing load. Expressed as force per unit cross-sectional area, e.g., pounds per square inch (psi).
Compressive StressesStresses created when forces push on a member and tend to shorten it.
CompressorA mechanical device for increasing the pressure of a gas.
Concentrated LoadAny load that acts on a very small area of a structure.
ConcreteA mixture of fine and course aggregates, portland cement, and water.
Concrete FootingGenerally, the wide, lower part of a foundation wall that spreads the weight of the building over a larger area. Its width and thickness vary according to weight of building and type of soil on which building is erected.
Concrete MasonryFactory manufactured concrete units, such as concrete brick or block.
Concrete PumpA pump that moves concrete through hoses to the area where it is to be placed.
CondemnationTaking private property for public use, with compensation to the owner, under the right of eminent domain.
CondensateA liquid formed by the condensation of vapor.
CondensationThe process of changing from a gaseous to a liquid state.
Condensation PointThe temperature at which a vapor liquefies if the latent heat is removed at standard ora stated pressure.
CondenserA heat-exchanger unit in which a vapor has some heat removed, causing it to form a liquid.
ConductionThe transfer of heat by direct molecular action.
Conduction, ThermalTransfer of heat from one part of a body to another part of that body, or to another body in contact, without any movement of bodies involved. The hot handle of a skillet is an example. The heat travels from the bottom of the skillet to the handle by conduction.
Conductivity, ElectricA measure of the ability of a material to conduct electric current.
Conductor, ElectricWire through which electric current flows.
ConduitA steel or plastic tube through which electrical wires are run.
Conforming UseLawful use of a building or lot that complies with the provisions of the applicable zoning ordinance.
ConiferousDescribing a cone-bearing tree or shrub.
ConsolidationThe process of compacting freshly placed concrete in a form.
ContourA line on a plan that connects all points of equal elevation.
Contour IntervalThe vertical distance between adjacent contour lines.
Control JointA groove formed in concrete or masonry structures to allow a place where cracking can occur, thus reducing the development of high stresses.
ControllerAn electric device or a group of devices used to govern the electric power delivered to the equipment to which it is connected.
ConvectionProcess of heat carried from one point to another by movement of a liquid or a gas (i.e., air). Natural convection is caused by expansion of the liquid or gas when heated. Expansion reduces the density of the medium, causing it to rise above the cooler, more dense portions of the medium. Gravity heating systems are examples of the profitable use of natural convection. The air, heated by the furnace, becomes less dense (consequently lighter) and rises, distributing heat to the various areas of the house without any type of blower. When a blower is used, the heat transfer method is called “forced convection.”
ConvectionThe process of carrying heat from one spot to another by movement of a liquid or gas. The heated liquid or gas expands and becomes lighter, causing it to rise while the cooler, heavier dense liquid or air settles.
ConvectorA unit designed to transfer heat from hot water or steam to the air by convection.
Cooling TowerA heat-transfer device in which the atmospheric air cools warm water flowing through the tower, usually by evaporation.
Corner BraceStructural framing member used to resist diagonal loads that cause racking of walls and panels due to wind and seismic forces. May consist of a panel or diaphragm, or diagonal flat strap or rod. Bracing must function in both tension and compression. If brace only performs in tension, two diagonal tension members must be employed in opposing directions as “X” bracing.
Corner LotA land parcel that fronts on two contiguous streets. The short side is generally considered to be the front of the lot.
Corner PostTimber or other member forming the corner of a frame. May be solid or built-up as a multi-piece member.
CorrosionThe deterioration of a metal or of concrete by chemical or electrochemical reaction caused by exposure to the weather.
Covalent BondingA process in which small numbers of atoms are bonded into molecules.
CovenantA restriction of the deed which regluates land use, aesthetic qualities, etc., of an area.
CreepPermanent dimensional deformation occurring over a period of time in a material subjected to constant stress at elevated temperatures.
Creep TestA test to determine the creep behavior of materials subjected to constant stress at a constant temperature.
CricketA small false roof used to divert water from behind a projection above the roof, such as a chimney.
CrippleShort stud such as that used between a door or window header and the top plate.
CrownThe central area of a conve surface, such as a road.
Cul-De-SacA short road with an outlet on one end and a turnaround on the other.
CulvertA length of pipe under a road or other barrier used to convey water.
CupolaA small roofed structure built on top of a roof, usually to vent the area below the roof.
CurbA low wall of wood or masonry extending above the level of the roof and surrounding an opening in the roof.
Curb CutA depression in a curb that provides vehicular access from a street to a driveway.
CureTo chemically cross-link polymer chains by heating and/or adding a chemical agent.
CuringProtecting concrete after placing so that proper hydration occurs.
Curing AgentPart of a two-part compound that, when added to the second part, sets up the curing action Also referred to as the catalyst.
Current, ElectricThe flow of electrons along a conductor.
Curtain WallExterior wall of a building that is supported by the structure and carries no part of the vertical load except its own. Curtain walls must be designed to withstand wind loads and transfer them to the structure.
Cut and FillIn grading, earth that is removed (cut) or added (fill).
Cycle (Acoustic)One full repetition of a motion sequence during periodic vibration. Movement from zero to +1 back to zero to -1 back to zero. Frequency of vibration is expressed in Hertz (cycles per second — see Frequency).
DamperA movable vane used to vary the volume of air passing through a duct, inlet, or outlet.
Damping CapacityThe ability of a material to absorb vibrational energy.
DarbyA tool used to level concrete in a form after it has been screeded.
Dead LoadLoad on a building element contributed by the weight of the building materials.
Decibel (dB)A unit for measuring sound energy or power. Adopted for convenience in representing vastly different sound pressures.
DeciduousDescribing trees that shed their leaves annually, as opposed to evergreen.
DecouplingSeparation of elements to reduce or eliminate the transfer of sound, heat or physical loads from one element to the other.
DeedA written instrument that is used to transfer real property from one party to another.
DeflectionDisplacement that occurs when a load is applied to a member or assembly. The dead load of the member or assembly itself causes some deflection as may occur in roofs or floors at mid-span. Under applied wind loads maximum deflection occurs at mid-height in partitions and walls.
Deflection LimitationMaximum allowable deflection is dictated by the bending limit of the finish material under the required design load (e.g., usually 5 psf for interior partitions).
DeformationChange in shape of a body brought about by the application of a force internal or external. Internal forces may result from temperature, humidity or chemical changes. External forces from applied loads can also cause deformation.
Degree DaysThe number of degrees that the mean temperature for any day at a particular locatoin is below 65 degrees Fahrenheit.
DehumidificationThe removal of water vapor from the air.
DehumidifierA cooling, absorption, or adsorption device used for removing moisture from the air.
DehydrationThe removal of water vapor from any substance.
DelaminationThe separation of the plies in a laminate or plies from a base material.
Density(1) With regards to materials, a measurement that compares the amount of matter an object has relative to its volume.(2) In city or site planning, a measure of the number of people, families, etc. that occupy a specified area.
DesiccantAny absorbent, adsorbent, liquid, or solid that removes water or water vapor from a material.
DesiccationThe process of evaporating or removing water vapor from a material.
Design LoadCombination of weight (dead load) and other applied forces (live loads) for which a building or part of a building is designed. Based on the worst possible combination of loads.
Dew PointThe temperature at which air becomes saturated (100 percent relative humidity) with moisture and below which condensation occurs. 
DewateringPumping subsurface water from an excavation to maintain dry and stable working conditions.
DiaphragmA horizontal roof or floor structural element designed to resist lateral loads and transmit them to shear walls (vertical resisting elements).
Dielectric StrengthThe maximum voltage a dielectric (nonconductor) can withstand without fracture.
DiffuserA circular, square, or rectangular air distributing outlet, usually in the ceiling, that has members to discharge supply air in several directions, mixing the supply air with the secondary air in the room.
Dimensional LumberLumber from 2 inches (50.8 mm) up to, but not including, 5 inches (127 mm) thick and 2 inches (50.8 mm) or greater in width.
Direct Current (DC)Electricity that flows in one direction.
Door BuckStructural element of a door opening. May be the same element as the frame if frame is structural, as in the case of heavy steel frames.
Double GlazingTwo parallel sheets of glass with an air space in between.
Double TeesT-shaped precast floor and roof units that span long distances unsupported.
Double-Hung WindowWindow sash that slides vertically and is offset in a double track.
Drainage(1) In buildings and infrastructure, the system by which excess water is collected, comducted, and dispersed.(2) In landscaping, the capacity of soil to receive and transmit water.
Dressed LumberLumber having one or more sides planed smooth.
DripInterruption or offset in an exterior horizontal surface, such as a soffit, immediately adjacent to the fascia. Designed to prevent the migration of water back along the surface.
Drip LineAn imaginary line on the ground described by the outermost branches of a tree.
DrivewayA vehicular path generally leading from a public street to a structure on private property.
Dry-Press ProcessThe process used to make bricks when the clay contains 10 percent or less moisture.
DrypackA stiff granular grout.
DrywallGeneric term for interior surfacing material, such as gypsum panels, applied to framing using dry construction methods, e.g., mechanical fasteners or adhesive. See SHEETROCK brand Gypsum Panels.
DuctA hollow tube through which air is circulated.
DuctileCapable of being stretched or deformed without fracturing (plastic deformation).
DuctilityA measure of the capability of a material to be stretched or deformed without breaking.
Dwelling UnitAn independent living area which includes its own private cooking and bathing facilities.
Dynamic LoadAny load that is nonstatic.
E ValueThe ratio of stress to strain.
EasementA limited right, whether temporary or permanent, to use the property of another in a certain way. This may include the right of access to water, light and air, right-of-way, etc.
EER (Energy Efficiency Ratio)The Btu output divided by the input in watts. The higher the EER the more efficient the equipment.
Effective TemperatureThe sensation produced by the combined effects of temperature, relative humidity, and air movement.
EfflourescenceA white soluble salt deposit on the surface of concrete and masonry, usually caused by free alkalies leached from the mortar by moisture moving through it.
EffluentPartially treated liquid sewage flowing from any part of a disposal system to a place of final disposition.
Elastic DeformationThe ability of a material to return to its original position after a load has been removed.
Elastic LimitThe greatest stress a material can withstand without permanent deformation upon the release of the stress.
ElasticityThe property of a material that causes it to return to its original shape upon removal of a deforming load.
ElastomerA macromolecular material that returns to its approximate initial dimensions and shape after being subjected to substantial deformation.
ElastomericHaving the properties of an elastomer.
Electric ConductionThe ability of a material to conduct an electric current.
Electric CurrentThe movement of electrons in an electric conductor.
Electric Current, AlternatingAn electric current that reverses the direction of flow periodically.
Electric Current, DirectAn electric current that does not reverse its polarity.
Electric PowerThe rate of generating, transferring, or using electric energy. It is expressed in watts (W) and kilowatts (kW).
ElevationThe vertical distance above sea level or other known point of reference.
ElevatorA hoisting and lowering mechanism equipped with an enclosed car that moves between floors in a building.
ElongationDrawing out to a greater length when under load of expansion due to temperature increases.
Eminent DomainThe right of a government, under the police power concept, to take private property for public use.
EnamelA classification of paints that dry to a hard flat semigloss or gloss finish.
EncroachmentPart of a building or an obstruction that extends into the property of another.
Epoxy FinishA clear finish having excellent adhesion qualities, abrasion and chemical resistance, and water resistance.
Epoxy ResinA class of synthetic thermosetting resins derived from certain special types of organic chemicals.
EquilibriumThe state of being equally balanced.
Equilibrium Moisture ContentThe moisture content at which wood neither gains nor loses moisture when surrounded by air at a specified relative humidity and temperature.
Erection PlanAn assembly drawing showing where each structural steel member is located on the building frame.
ErosionThe process by which the surface of the earth is worn away by the action of natural elements, such as water and wind. Also referred to as Weathering.
EscalatorA continuous moving stair used to move people up and down between floors.
EvaporatorThat part of a refrigerating system in which the refrigerant is evaporated, allowing it to absorb heat from the contactin heat source.
EvergreenHaving green leaves throughout the year, as opposed to deciduous.
ExcavationThe digging or removal of earth.
Expansion JointA joint used to separate two parts of a building to allow expansion and contraction movement of the parts.
Expansive SoilClay that swells when wet and shrinks when dried.
Exposed Aggregate FinishA finished concrete surface in which a coarse aggregate is exposed to view.
Exterior Insulation and Finish SystemExterior cladding assembly consisting of a polymer finish over a reinforcement adhered to foam plastic insulation that is fastened to masonry, concrete, building sheathing or directly to the structural framing. The sheathing may be cement board or gypsum sheathing.
ExtrapolateTo project tested values, assuming a continuity of an established pattern, to obtain values beyond the limit of the test results. Not necessarily reliable.
ExtrudingA process in which a billet of material is shaped into a strip having a uniform cross section by forcing the material through a die.
Face BrickBrick made or selected to produce an attractive exterior wall.
Faceted Glass WindowA window made by bonding 1 inch (25.4 mm) thick glass pieces with an epoxy resin matrix or reinforced concrete.
Factor of SafetyRatio of the ultimate unit stress to the working or allowable stress.
Fahrenheit TemperatureThe temperature scale on which. at standard atmospheric pressure. the boiling point of water is 212 degrees Fahrenheit, the freezing point is 32 degrees Fahrenheit, and absolute zero is 2459.69 degrees Fahrenheit.
Fan Coil UnitThe fan and heat exchanger for cooling and heating that are assembled in a common cabinet.
FasciaBoard fastened to the ends of the rafters or joists forming part of a cornice.
Fast TrackMethod that telescopes or overlaps traditional design-construction process. Overlapping phases as opposed to sequential phases is keynote of the concept.
FatigueCondition of material under stress that has lost, to some degree, its power of resistance as a result of repeated application of stress, particularly if stress reversals occur as with positive and negative cyclical loading.
Fatigue LimitThe number of cycles of loading of a specified type that a specified material can withstand before failure.
Fatigue StrengthA measure of the ability of a material or structural member to carry a load without failure when the loading is applied a specified number of times.
Fatigue TestA test to determine the behavior of a material under fluctuating stresses.
FeltA sheet material made using a fiber mat that has been saturated and topped with asphalt.
FenestrationAn area that allows light to pass into a building, commonly referring to glazed windows. Also, the arrangement of windows in an exterior wall.
FerrousIron-based metallic materials.
Fiber Saturation PointThe moisture content of wood at which the cell walls are saturated but there is no water in the cell cavities.
FiberboardA panel made from vegetable fibers and binding agents.
FillerAn inert material added to a plastic resin to alter the strength and working properties and to lower the cost.
Finish CoatThe third or final coat of gypsum plaster.
Finish FloorThe flooring that is left exposed to view.
Finish Floor LevelThe completed floor surface on which building occupants walk.
Finish GradeThe elevation of the ground surface after completion of all work.
Finish LimeA hydrated lime used in finish coats of plaster and in ornamental plasters.
Finish PlasterThe topcoat of plaster on a wall or ceiling.
Fire EnduranceMeasure of elapsed time during which an assembly continues to exhibit fire resistance under specified conditions of test and performance. As applied to elements of buildings, it shall be measured by the methods and to the criteria defined in ASTM. Methods E119, Fire Tests of Building Construction and Materials; ASTM Methods E152, Fire Tests of Door Assemblies; ASTM Methods E814, Fire Test of Through-Penetration Fire Stops; or ASTM Methods E163, Fire Tests of Window Assemblies.
Fire ResistanceRelative term, used with a numerical rating or modifying adjective to indicate the extent to which a material or structure resists the effect of fire.
Fire Resistant GypsumA gypsum product that has increased fire-resistance properties due to the addition of fire-resistant materials in the gypsum core.
Fire StopObstruction in a cavity designed to resist the passage of flame, sometimes referred to as “fire blocking.”
Fire TapingThe taping of gypsum board joints without subsequent finishing coats. A treatment method used in attic, plenum or mechanical areas where aesthetics are not important.
Fire WallFire-resistant partition extending to or through the roof of a building to slow the spread of fire. See Area Separation Wall.
Fire-Rated PartitionA partition assembly that has been tested and given a rating indicating the length of time it will resist a fire in hours.
Fire-ResistiveRefers to properties or designs to resist effects of any fire to which a material or structure may be expected to be subjected.
Fire-RetardantDenotes substantially lower degree of fire resistance than fire-resistive. Often used to describe materials that are combustible but have been treated to slow ignition or spread of fire under conditions for which they were designed.
FirebrickA brick made from special clays that will withstand high temperatures.
FireclaysDeep mined clays that withstand heat.
FireproofUse of this term in reference to buildings is discouraged because few, if any, building materials can withstand extreme heat for an extended time without some effect. The term “fire-resistive” or “resistant” is more descriptive.
FireproofingA material used to protect various members from damage due to fire.
Flame SpreadIndex of the capacity of a material to spread fire under test conditions, as defined by ASTM Standard E84. Materials are rated by comparison with the flame-spread index of red oak flooring assigned a value of 100 and inorganic reinforced cement board assigned a value of 0.
Flame Spread RateThe rate at which flames will spread across the surface of a material.
Flame Spread RatingA numerical designation given to a material to indicate its comparative ability to restrict flaming combustion over its surface.
FlammabilityThe ability of a material to resist burning.
FlammableCapability of a combustible material to ignite easily, burn intensely or have rapid rate of flame spread.
Flanking PathsPaths by which sound travels around an element intended to impede it, usually some structural component that is continuous between rooms and rigid enough to transmit the sound. For example, a partition separating two rooms can be “flanked” by the floor, ceiling or walls surrounding the partition if they run uninterrupted from one room to the other. Ducts, conduits, openings, structural elements, rigid ties, etc., can be sound flanking paths. The acoustic effect of sound flanking paths is dependent on many factors.
Flash PointThe temperature at which a flammable material will suddenly break into a flame.
Flash SetVery rapid setting of the cement in concrete.
FlashingStrips of metal or waterproof material used to make joints waterproof, as in the joining of curtain wall panels.
FloatA flat hand tool used to smooth the surface of freshly placed concrete after it has been leveled with a darby.
Float ProcessA glass manufacturing process in which the molten glass ribbon flows through a furnace supported on a bed of molten metal.
Flocked ConstructionCarpet formed by electrostatically spraying short strands onto an adhesive-coated backing material.
Flood CoatA heavy coating of asphalt poured and spread over a surface.
Flood PlainThe land surrounding a flowing stream over which water spreads when a flood occurs.
Floor Area Ratio (FAR)The ratio of the floor area of a building to the area of the lot.
Flow LineThe path down which water flows.
FluourescenceThe emission of visible light from a substance as a result of the absorption of radiation of short wavelengths.
FluxA mineral added to molten iron to cause impurities to separate into a layer of molten slag on top of the iron.
Flying FormworkLarge sections of formwork for pouring concrete slabs that are lifted from story to story by a crane in an assembled condition.
FootcandleThe unit of illumination equal to 1 lumen per square foot.
FootingLower extremity of a foundation or loadbearing member that transmits load to load-bearing substrate.
FootingThe lowest, widest part of the foundation that distributes the load over a broad area of the soil.
FootlambertA unit for measuring brightness or luminance. It is equal to 1 lumen per square foot when brightness is measured from the surface.
ForceAmount of applied energy to cause motion, deformation or displacement and stress in a body.
FormworkTemporary construction used to contain and give shape and support to concrete as it cures.
FoundationComponent that transfers weight of building and occupants to the earth.
Framed ConnectionsConnections joining structural steel members with a metal, such as an angle, that is secured to the web of the beam.
Framing PlanA drawing showing the location of structural members.
Freezing Cycle DayA day when the temperature of the air rises above or falls below 32 degrees Fahrenheit or 0 degrees Celcius.
Freezing PointThe temperature at which a given substance will solidify (freeze).
Frequency (Sound)Number of complete vibrations or cycles or periodic motion per unit of time.
Front YardIn zoning, the minimum legal distance between the front property line and a structure.
FrontageThe length of a lot line along a street or other public way.
Frost LineThe maximum depth in the earth to which the soil can be expected to freeze during a severe winter.
Frost PointThe temperature at which frost forms on exposed, chilled surfaces.
Fuel ContributedA rating of the amount of combustible material in a coating.
FurringMember or means of supporting a finished surfacing material away from the structural wall or framing. Used to level uneven or damaged surfaces or to provide space between substrates. Also an element for mechanical or adhesive attachment of paneling.
FuseAn overcurrent protection device that opens an electric circuit when the fusible element is broken by heat due to overcurrent passing through it.
Fusion-Bonded ConstructionCarpet formed by bonding pile yearn between two sheets of backing material and cutting the pile yarn in the center, forming two pieces of carpet.
GableUppermost portion of the end wall of a building that comes to a triangular point under a sloping roof.
GallingThe wearing or abrading of one material against another under extreme pressure.
Galvanic CorrosionCorrosion that develops by galvanic action when two dissimilar metals are in contact in the atmosphere.
Gearless Traction ElevatorAn elevator with the traction sheave connected to a spur gear that is driven by a worm gear connected to the shaft of the electric motor.
GirderBeam, especially a long, heavy one; the main beam supporting floor joists or other smaller beams.
GlassAn inorganic mixture that has been fused at a high temperature and cooled without crystallization.
Glazed Structural Clay TileHollow clay tile products with glazed faces typically used to build interior walls.
Glue Laminated Lumber (Glulam)A structural wood member made by bonding together laminations of dimension lumber.
GluesBonding agents made from animal and vegetable products.
Grade1. Related to soil, the elevation or slope of the ground.2. In relation to lumber, a means of classifying lumber or other wood products based on specified quality characteristics.
Grade BeamA ground-level reinforced structural member that supports the exterior wall of a structure and bears directly upon columns or piers.
Grade LevelThe elevation of the soil at a specific location.
Grade MarkA stamp on a product, such as wood, plywood, or steel, indicating the product’s capacity.
GradientThe rate of slope between two points on a surface, determined by dividing their difference in elevation by their distance apart.
GradingAdjusting the level of the ground on a site.
GradingThe modification of earth to create landforms.
GravelHard rock material in particles larger than 1/4 inch (6.4 mm) in diameter but smaller than 3 inches (76 mm).
Green LumberLumber having a moisture content more than 19 percent.
GreenbeltA belt-like area around a city, reserved by ordinance for parkland, farms, open space, etc.
Greenhouse EffectThe direct gain of solar heat, generally through south-facing glass walls and roofs.
GrilleAn open gate used to cover, conceal, protect, or decorate an opening.
GroundA conducting connection between an electrical circuit and the earth or a conducting body that serves in place of the earth.
Ground-Fault Circuit InterrupterA device providing protection from electric shock by de-energizing a circuit within an established period of time when the current to ground exceeds a predetermined value that is less than that needed to activate a standard overcurrent protective device.
GroundwaterWater that exists below the surface of the earth and passes through the subsoil.
Groundwater LevelThe plane below which the soil is saturated with water. Also called Groundwater Table or Water Table.
GroutA viscous mixture of Portland cement, water, and aggregate used to fill cavities in concrete. Also refers to a specially formulated mortar used to fill under the baseplates of steel columns and in connection in precast concrete.
GussetWood or metal plate riveted, bolted, glued or pressed (wood trusses) over joints to transfer stresses between connected members.
GypsumHydrous calcium sulfate.
Gypsum BackerboardA gypsum panel used as the base on which to bond tile or gypsum wallboard.
Gypsum BoardA gypsum panel used as the base on which to bond tile or gypsum wallboard.
Gypsum LathA panel having a gypsum core and a paper covering providing a bonding surface for plaster.
Gypsum PlasterGround gypsum that has been calcined and mixed with additives to control setting time and working qualities.
Gypsum SheathingA gypsum panel with a water-repellent core. Used for sheathing exterior walls.
HachureA shading technique used to depict ground form.
HardboardA general term used to describe a panel made from interfelted lignocellulose fibers consolidated under heat and pressure.
HardnessA measure of the ability of a material to resist indention or surface scratching.
HardwoodA botanical group of trees that have broad leaves that are shed in the winter (it does not refer to the hardness of the wood).
Hardwood PlywoodPlywood with various species of hardwoods used on the outer veneers.
HaunchA projection used to support a member, such as a beam.
Header JoistA structural member fastened between two parallel full-length framing members to support cut off members at the openings.
HeartwoodThe wood extending from the pith to the sapwood.
HeatForm of energy thought to be characterized by the rate of vibration of the molecules of a substance. The hotter the substance, the faster the molecules vibrate. On the other hand, when there is no heat present it is thought the molecules will be at rest, which theoretically occurs at absolute zero, -459.7°F (-273.15°C or 0.0°K).
Heat ExchangerA device to transfer heat between two physically separated fluids.
Heat LossThe energy needed to warm outside air leaking into a building through cracks around doors, windows, and other places.
Heat PumpA heating/refrigerating system in which heat is taken from a heat source, such as the air, and given up to the space to be heated. For cooling, it takes heat from the air in the space and gives it up outdoors.
Heat Quantity (Btu)Common unit of measure of the quantity of heat is the British Thermal Unit (Btu). One Btu is the amount of heat required to raise one pound of water from 63° to 64°F (1 Btu = 1055.06 J). This is about the amount of heat given off by one wooden match. A pound of coal can produce 13,000 Btu.
Heat TransferHeat always flows toward a substance of lower temperature until the temperatures of the two substances equalize. It travels by one or more of three methods: conduction, convection or radiation.
Heat TreatingHeating and cooling a solid metal to produce changes in physical and mechanical properties.
Heat-Strengthened GlassGlass that has been strengthened by heat treatment.
Heat-Treatable AlloysAluminum alloys whose strength characteristics can be improved by heat treatment.
Heating ValueThe amount of heat produced by the complete combustion of a unit quantity of fuel.
Heavy Timber ConstructionA type of wood-frame construction using heavy timbers for the columns, beams, joists, and rafters.
Heel of RafterSeat cut in a rafter that rests on the wall plate.
HertzThe units of measure of sound frequency, named for Heinrich H. Hertz. One Hertz equals one cycle per second.
Hiding PowerThe ability of a paint to hide the previous color or substrate.
Hinge JointA joint that permits some action similar to a hinge and in which there is no appreciable separation of the joining members.
Hip RoofA roof consisting of four sloping planes that intersect forming a pyramidal shape.
Hoistway, ElevatorA fire-resistant vertical shaft in which the elevator moves.
Hollow BrickA clay masonry unit whose net cross sectional area in the plane of the bearing surface is not less than 60 percent of the gross cross sectional area of that face.
Hollow Clay MasonryA unit whose core area is 25 to 40 percent of the gross cross-sectional area of the unit.
Hollow Concrete MasonryConcrete masonry units that have open cores.
Hollow-Core DoorA door with face veneers on the outer surfaces, wood spacers around the edges, and a hollow interior supported with a honey-comb grid.
Holow-Core SlabA precast concrete structural slab that uses internal cavities to reduce its weight.
HoneycombAny substance having cells suggesting a mass of cells such as those built by the honeybee. Some hollow-core doors use the honeycomb principle in their construction.
Horizontal SheerThe tendency of the top wood fibers to move horizontally in relationship to the bottom fibers.
Hot MeltAdhesives that bond when they are heated to a liquid form.
HUDHousing and Urban Development, federal agency.
HUD Mobile Home StandardsOfficially, the National Mobile Home Construction and Safety Standards Act of 1974 for construction of mobile homes. Includes the following agencies: DAPIA Design Approval Primary Inspection Agency and IPIA Production Inspection Primary Inspection Agency.
HumidifierA device used to add moisture to the air.
HumidityThe amount of water vapor withing a given space.
HumidityThe amount or degree of moisture in the air.
HVACHeating, ventilating and air conditioning (ASHRAE Guide is the technical reference source).
HydrateThe capacity of lime to soak up water serveral times its weight.
Hydrated LimeCalcium hydroxide made by burning calcium carbonate, which forms caclium oxide that can then chemically combine with water.
HydrationA chemical reaction between water and cement that produces heat and causes the cement to cure or harden.
Hydraulic ElevatorAn elevator having the car mounted on top of a hydraulic piston that is moved by the action of hydraulic oil under pressure.
Hydraulic MortarA mortar that is capable of setting and hardening under water.
Hydronic Heating SystemA system that circulates hot water through a system of pipes and convectors to heat a building.
HydronicsThe science of cooling and heating water.
Hydrostatic PressureThe pressure equivalent to that exerted on a surface by a column of water of a specified height.
Hydroxide of LimeThe product produced by the chemical reaction during the slaking or hydrating of lime.
HygrometerAn instrument used to measure humidity conditions of the air.
Hygrometric ExpansionAll materials, particularly those of organic origin, expand and contract in relation to their moisture content, which varies with environment. The Hygrometric Coefficient of Expansion is expressed in “Inches Per Inch Per Percent Of Relative Humidity.” Example: gypsum board has a coefficient of 7.2 x 10-6 in. per in. per %rh. This means that with an increase in relative humidity of from 10% to 50%, a gypsum board wall 300 ft. long will have an unrestrained linear expansion of 1.0368″ or 1&1/32″.
HygroscopicThe ability to readily absorb and retain moisture from the air.
HzThe abbreviation for hertz, the unit of measurement of the frequency of electric current. It represents the number of cycles per second.
I JoistA wood joist made of an assembly of laminated veneer wood top and bottom flanges and a web of plywood or oriented strandboard.
ICBOInternational Conference of Building Officials, a nonprofit organization that publishes the Uniform Building Code.
Igneous RockRock formed by the solidification of molten material to a solid state.
IlluminanceThe density of luminous power in lumens per a specified area.
Impact Insulation ClassAn index of the extent to which a floor assembly transmits impact noise from a room above to the room below.
Impact Insulation Class (IIC)Single-number rating used to compare and evaluate the performance of floor-ceiling constructions in isolating impact noise. The advantages of this rating system are positive values and the correlation with Sound Transmission Class (STC) values — both providing approximately equal isolation at a particular value. The IIC rating is used by building agencies for specifying minimum sound-control performance of assemblies in residential construction.
Impact NoiseSound generated by impact on the floor or other parts of a building that is carried through the building.
Impact Noise Rating (INR)Obsolete rating system for floor-ceiling construction in isolating impact noise. INR ratings can be converted to approximate IIC ratings by adding 51 points; however, a variation of 1 or 2 points may occur.
Impact StrengthThe energy required to fracture a specimen when struck with a rapidly applied load.
Impact TestA test for determining the resistance of a specimen fracture from a high-velocity blow.
In SituUndisturbed soil.
IncandescenceThe emission of visible light produced by heating.
IncombustibleSee Noncombustible.
Independent FootingsFootings supporting a single structural element, such as a column.
InfiltrationThe process by which water soaks into the ground. Also called Percolation.
IngotA mass of molten metal cast in a mold and solidified to be stored until used for forging or rolling into a finished product.
InsolationThe amount of solar radiation on a given plane or surface.
Insulatig GlassA glazing unit used to reduce the transfer of heat through a glazed opening by leaving an air space between layers of glass.
Insulation (Thermal)Any material that measurably retards heat transfer. There is wide variation in the insulating value of different materials. A material having a low density (weight/volume) will usually be a good thermal insulator.
Insulation, ElectricA material that is a poor conductor of electricty.
InterceptorA trapping device designed to collect materials that will not be able to be handled by a sewage treatment plant, such as grease, glass or metal chips, and hair.
InterpolateTo estimate untested values that fall between tested values.
IntumescenceThe swelling of a fire-retardant coating when heated, which forms a low-density film that provides some resistance to the spread of flame on the surface.
Invert ElevationThe elevation of the bottom (flow line) of a pipe.
IronA metallic element existing in the crust of the earth from which ferrous alloys, such as cast iron, are made.
ISOInternational Standards Organization, an organization similar in nature.
JambOne of the finished upright sides of a door or window frame.
Jamb StudWood or metal stud adjacent to the door jamb.
Joint CompoundA plastic gypsum mixture used to cover the joints and fasteners in gypsum wallboard installations.
JointingForming control joints in a concrete slab.
JoistSmall beam that supports part of the floor, ceiling or roof of a building.
Joist HangerMetal shape formed for hanging on the main beam to provide support for the end of a joist.
JouleA meter-kilogram-second unit of work or energy.
JuteA coarse fiber obtained from two East Indian tiliaceous plants.
Keene’s CementA hard, high-strength, white, quick-setting finishing plaster made from burnt gypsum and alum.
Kiln(1) A chamber with controlled humidity, temperature, and airflow in which lumber is dried.(2) A low-pressure steam room in which green concrete units are cured.
Kiln-Dried LumberLumber that has been dried and seasoned with carefully controlled heat in a kiln.
Kinetic EnergyThe energy of a body with respect to the motion of the body.
Knitted ConstructionCarpet formed by looping pile yarn, stitching, and backing together.
TermDefinition
Label Service (UL)Program allowing a manufacturer to place Underwriters Laboratories Inc. labels on his products that have met UL requirements. A UL representative visits the manufacturing location to obtain samples of the products for testing by UL. In some cases, samples are also purchased on the open market for testing. The public is thereby assured that products bearing the UL label continually meet UL specifications.
LacquerA fast-drying clear or pigmented coating that dries by solvent evaporation.
LaminateA material made by bonding several layers of material.
Laminate WoodA product made by bonding layers of wood or other material to a wood substrate.
Laminated GlassGlass panels that have outer layers of glass laminated to an inner layer of transparent plastic.
Laminated Veneer LumberA structural lumber manufactured from wood veneers so that the grain of all veneers runs parallel to the axis of the member.
LampA general term used to describe the source of artificial light. Often called a bulb or tube.
Landing Zone, ElevatorThe area 18 inches (5490 mm) above or below the landing floor.
Latent HeatHeat involved with the action of changing the state of a substance, such as changing water to steam.
Lateral ForceA force acting generally in a horizontal direction, such as wind against an exterior wall or soil pressure against a foundation wall.
Lateral LoadsLoads moving in a horizontal direction, such as the wind.
LatexA water-based coating, such as styrene, butadiene, acrylic, and polyvinyl acetate.
LathThe base material for the application of plaster.
Leaks (Sound)Small openings at electrical boxes and plumbing, cracks around doors, loose-fitting trim and closures all create leaks that allow sound to pass through, reducing the acoustical isolation of a wall, floor or ceiling system.
Ledger StripStrip fastened to the bottom edge of a flush girder to help support the floor joists.
Leveling PlateA steel plate set in grout on top of a concrete foundation to create a level bearing surface for the base of a steel column.
Life-Cycle CostingSelection of the most economical material and systems based on initial costs, maintenance costs and operating costs for the life of the building.
Lift-Slab ConstructionA method of building site-cast concrete buildings by casting all the floor and roof slabs in a stack on the ground and lifting them up the columns with a series of jacks and welding them in place.
LightA pane of glass.
Light-Gauge Steel Structural MembersLoad-bearing members formed from light-gauge steel rolled into structural shapes.
Lighting FixtureSee luminaire.
Lighting OutletAn electrical outlet to which a light fixture is connected.
Lightweight Steel FramingStructural steel framing members made from cold-rolled lightweight sheet steel.
LigninAn amorphous substance that penetrates and surrounds the cellulose strands in wood, binding them together.
LimeA white to gray powder produced by burning limestone, marble, coral, or shells.
LimestoneA sedimentary rock consisting of calcium and magnesium.
Limiting HeightMaximum height for design and construction of a partition or wall without exceeding the structural capacity or allowable deflection under given design loads.
LintelHorizontal member spanning an opening such as a window or door. Also referred to as a Header.
Liquid LimitRelated to soils, the water content expressed as a percentage of dry weight at which the soil will start to flow when tested by the shaking method.
Live LoadPart of the total load on structural members that is not a permenant part of the structure. May be variable, as in the case of loads contributed by the occupancy, and wind and snow loads.
LoadForce provided by weight, external or environmental sources such as wind, water and temperature, or other sources of energy.
Load-BearingCarrying an imposed load.
Loomed ConstructionCarpet formed by bonding the pile yarn to a rubber cushion.
Lot AreaTotal horizontal area within the lot lines of a parcel of land.
Lot LineThe boundary line of a lot.
LoudnessSubjective response to sound pressure, but not linearly related thereto. A sound with twice the pressure is not twice as loud. See Decibel.
LouverOpening with slanted fins (to keep out rain and snow) used to ventilate attics, crawl spaces and wall openings.
Low-E GlassA low-emissivity glass that has a thin metallic coating that selectively reflects ultraviolet and infrared wavelengths of the energy spectrum.
Low-Emissivity CoatingA surface coating used on glass that permits the passage of most shortwave electromagnetic radiation (light and heat) but reflects longer-wave radiation (heat).
Low-Slope RoofsRoofs that are nearly flat.
LumberA product produced by harvesting, sawing, drying, and processing wood.
Lumber GraderA person who inspects each piece of lumber and assigns a grade to it.
Lumber, BoardsLumber nominally less than 2 inches thick and 2 inches or more in width.
Lumber, DimensionLumber cut and dressed to standard sizes.
Lumber, Dressed SizeThe size of lumber after it has been cut to size and the surfaces planed.
Lumber, Machine Stress-RatedLumber that has been mechanically tested to determine its stiffness and bending strength.
Lumber, MatchedLumber that is edge dressed to make close tongue-and-groove edge joints.
Lumber, Nominal SizeThe size of lumber after it has been sawn to size but has not been surfaced.
Lumber, PatternedLumber that is shaped to a pattern or to a molded form.
Lumber, RoughLumber that has not been surfaced but may be sawn, edged, and trimmed.
Lumber, ShiplappedLumber that is edge dressed to make a lapped joint.
Lumber, Shop and FactoryLumber intended to be cut up and used in some manufacturing process.
Lumber, StructuralLumber that is intended for use where allowable strength or stiffness of the piece is known.
LumenA unit for measuring the flow of light energy.
LuminaireA complete lighting unit consisting of one or more lamps plus elements needed to distribute light, hold and protect the lamps, and connect power to the lamps. Also called a lighting fixture.
Luminancethe luminous intensity of a surface of a given area viewed from a given direction.
Luminance MeterA photoelectric instrument used to measure luminance. Also called a light meter.
LuminescenceThe emission of light not directly caused by incandescence.
Luminous FluxThe rate of flow of light energy through a surface, expressed in lumens.
Luminous IntensityThe force that generates visible light express by candela, lumens per steradian, or candlepower.
Luminous TransmittanceA measure of the capacity of a material to transmit incident light in relation to the total incident light striking it.
LuxA unit of illumination equal to 1 lumen per square meter.
Makeup AirAir brought into a building from the outside to replace air that has been exhausted.
MalleabilityThe property of a metal that permits it to be formed mechanically, such as by rolling or forging, without fracturing.
ManholeAn access hole in a drainage system to allow inspection, cleaning, and repair.
MarbleA metamorphic rock formed largely of calcite, dolomite, or dense limestone.
Masonry CementA hydraulic cement used in mortars to increase plasticity and water retention.
MassProperty of a body that resists acceleration and produces the effect of inertia. The weight of a body is the result of the pull of gravity on the body’s mass.
MasterFormatThe trademarked title of a uniform system for indexing construction specifications published by the Construction Specifications Institute and Construction Specifications Canada.
MasticA doughlike compound available in many different formulations designed for use as sealants and adhesives.
Mat FoundationA large, single concrete footing equal in area to the area covered by the footprint of the building.
Mechanical ActionThe bonding of materials by adhesives that enter the pores and harden, forming a mechanical link.
Mechanical PropertiesProperties exhibited by a material’s reaction to applied forces, such as tensile strength and compressive strength.
MelamineA white crystalline made from calcium cyanamide.
Melting TemperatureThe temperature at which a material turns from a solid to a liquid.
MembraneA continuous, unbroken roof covering.
Metal LathPerforated sheets of thin metal secured to studs that serve as the base for a finished plaster wall.
Metamorpihic RockRock formed by the action of pressure and/or heat on sedimentary soil or rock.
Meter, ElectricA device measuring and recording the amount of electricity passing through it in kilowatt-hours.
Metes and BoundsA formal description of the boundary lines of a parcel of real property in terms of the length and direction of those lines.
Metric TermsMetric units shown as equivalents in this Handbook are from the International System of Units in use throughout the world, as established by the General Conference of Weights and Measures in 1960. Their use here complies with the Metric Conversion Act of 1975, which committed the United States to a coordinated voluntary conversion to the metric system of measurement. Refer to the Appendix for metric units and conversion factors applicable to subjects covered in this Handbook. For additional information, refer to ASTM E380-76, Standard for Metric Practice.
Mild SteelSteel containing less than 0.3 percent carbon.
MildeweideAn agent that helps prevent the growth of mold and mildew on painted surfaces.
MillworkWood interior finish items manufactured in a factory, such as doors, windows, and cabinets.
MiterJoint formed by two pieces of material cut to meet at an angle.
Model CodeBuilding code, written and published by a building-official association, available to states, counties and municipalities for adoption (for a fee) in lieu of their own, e.g., Uniform Building Code, Standard Building Code, National Building Code.
Modified BitumensA roofing membrane composed of a polyester or fiberglass mat saturated with a polymer-modified asphalt.
Modular SizeA dimension that conforms to a given module, such as the 48-inch width of plywood panels.
Module(1) In architecture, a selected unit of measure used as a basis for building layout; (2) In industrialized housing, a three-dimensional section of a building, factory-built, shipped as a unit and interconnected with other modules to form the complete building. Single-family units factory-built in two halves are usually referred to as “sectionals.”
Modulus of Elasticity (E)Ratio between deformation, a measure of the stiffness of a material.
Modulus of RuptureA measure of the ultimate load-carrying capacity of a structural member.
Moisture BarrierA membrane used to block the passage of water, and water vapor through an assembly of materials, suh as a wall.
Moisture ContentThe amount of water contained in wood expressed as a percentage of the weight of the wet wood to the weight of an oven-dry sample.
MomentThe tendency of a force to cause rotation about a give point or axis.
Moment of Inertia (I)Calculated numerical relationship (expressed in in.4) of the resistance to bending of a member, a function of the cross-sectional shape and size. A measure of the stiffness of a member based on its shape. Larger moments of inertia indicate greater resistance to bending for a given material.
Monolythic ConcreteConcrete cast with no joints except construction joints: a continuous pour.
MonomerAn organic molecule that can be converted into a polymer by chemical reaction with similar molecules or organic molecules.
MortarA plastic mixture of cementitious materials, water, and fine aggregate.
Mortar FlowA measure of the consistency of freshly mixed mortar related to the diameter of a molded truncated cone specimen after the sample has been vibrated a specified number of times.
MosaicA decoration made up of small pieces of inlaid stone, glass, or tile.
Motor ControlA device that governs the electric power delivered to one or more electric motors.
Motor Control CenterControllers used to start and stop electric motors and protect them from overloads.
Moulding (also Molding)Narrow decorative strip applied to a surface.
Moving RampA conveyor belt system used to move people or packages up or down an incline.
Moving WalkA conveyor belt system operating at floor level used to move people in a horizontal direction.
MullionVertical bar or division in a window frame separating two or more panes.
Multiple DwellingA building containing three or more dwelling units.
MuntinHorizontal bar or division in a window frame separating multiple panes or lights.
Music/Machinery Transmission Class (MTC)Rating developed by U.S. Gypsum Company to isolate music and machinery/mechanical equipment noise or any sound with a substantial portion of low frequency energy. MTC does not replace Sound Transmission Class (STC) but complements it.
Nail PopThe protrusion of the nail usually attributed to the shrinkage of or use of improperly cured wood framing.
Nail PoppingThe loosening of nails holding gypsum board to a wall or ceiling. It produces a bulge in the surface of the gypsum panel.
Natural FibersFibers found in nature, such as wool and cotton.
NBFUNational Board of Fire Underwriters, now merged into the American Insurance Assn.
NBSNational Bureau of Standards, a federal agency.
NCSBCSNational Conference of States on Building Codes and Standards, a nonprofit organization formed to increase interstate cooperation and coordinate intergovernmental reforms of building codes.
Neat PlasterA gypsum plaster with no aggregates or fillers added. Sometimes called unfibered gypsum.
Needle BeamA steel or wood beam that is run through an opening in a bearing wall and used to support the wall and related loads as work on the foundation below the wall is performed.
Neutral AxisThe plane through a member (at the geometric center of the section in symmetrical members) where the fibers are neither under tensile nor compressive stress.
NFiPANational Fire Protection Assn., an international technical society that disseminates fire prevention, fighting and protection information. NFiPA technical standards include the National Electrical Code which is widely adopted.
NFoPANational Forest Products Association.
Noise Reduction Coefficient (NRC)A single number indicated by the amount of airborne sound energy absorbed into a material. The arithmetic average of sound absorption coefficients at 250, 500, 1000 and 2000 Hz.
NominalTerm indicating that the full measurement is not used; usually slightly less than the full net measurement, as with 2″ x 4″ studs that have an actual size when dry of 1&1/2″ x 3&1/2″.
Non-Conforming UseA particular use of land or a structure which is in violation of the applicable zoning code. Generally, if the use was established prior to the code rule which it contravenes, it may continue to exist.
NonbearingRefers to a structural part that does not carry a load.
Noncalcerous ClaysClays containing silicate of alumina, feldspar, and iron oxide.
NoncombustibleDefinition excerpted from the ICBO Uniform Building Code: 1. Material of which no part will ignite and burn when subjected to fire. 2. Material having a structural base of noncombustible material as defined, with a surface not over 1/8″ thick that has a flame spread rating of 50 or less. The term does not apply to surface finish materials.
Nondestructive TestingMethods of testing an item that do not destroy the item being tested.
NonferrousMetallic materials in which iron is not a principal element.
Nonheat-Treatable AlloysAlloys that do not increase in strength when they are heat treated but that do gain strength by the addition of alloying elements.
Nonprestressed UnitsConcrete structural members in which the reinforcing steel is not subject to prestressing or post-tensioning.
NylonA synthetic plastic made from coal, tar, and water.
OakumA caulking material made from hemp fibers treated with tar.
OctaveInterval between two sounds having a basic frequency ratio of two. The formula is 2n times the frequency, where n is the desired octave interval. The octave band frequency given in sound test results is usually the band center frequency, thus the 1000 Hz octave band encompasses frequencies from 707 Hz to 1414 Hz (n = ± 1/2). The 1000 Hz one-third-octave band encompasses frequencies from 891 Hz to 1122 Hz (n = ± 1/6).
Oil-Based PaintPaint composed of resins requiring solvent for reduction purposes.
Opaque CoatingsCoatings that completely obscure the color and much of the texture of the substrate.
Open DrainageThe removal of unwanted water by means of surface devices.
Open-Web JoistA prefabricated steel truss made of welded members, used for floor and roof construction.
Organic MaterialA class of compounds comprising only those existing in plants and animals.
Oriented Strand BoardA panel made from wood strands that have their strand face oriented in the long direction of the panel.
Outlet BoxA box that is part of the electrical wiring system that contains one or more receptacles.
Overlaid PlywoodPlywood panels whose exterior surfaces are covered with a resin-impregnated fiber ply.
OverloadThe operation of electrical equipment in excess of the normal full-loaded electrical rating or of a conductor carrying current in excess of its rated capacity.
OxidationA reaction between a material and oxygen in the atmosphere.
Oxide LayerIn aluminum, a very thin protective layer formed naturally on aluminum due to its reaction to oxygen.
OxidizeTo convert an element into oxide, such as rusting steel.
PadAn approximately level building area.
PanA metal form used to form the cavities between joists in cast-in-place concrete floors and roofs.
PanelboardA panel that includes fuses or circuit breakers used to protect the circuits in a building from overloads.
Panelized ConstructionConstruction that uses preassembled panels for walls, floors, and roof.
Parallel Strand LumberLumber made from lengths of wood veneer bonded to produce a solid member.
Parapet WallExtension of an exterior wall above and/or through the roof surface.
PargingThe application of a portland cement plaster on masonry and concrete walls to make them less permeable to water.
ParticleboardA sheet product manufactured from wood particles and a synthetic resin or other binder.
PartitionA non-load-bearing interior wall.
Party WallA wall built on the dividing line between two adjoining parcels, in which each owner has an equal share of ownership.
Passive Solar SystemA heating or cooling system that collects and moves solar heat whiout using mechanical power.
PaverA thin brick used as the finished floor covering.
Penny (d)Suffix designating the size of nails, such as 6d (penny) nail, originally indicating the price, in English pence, per 100 nails. Does not designate a constant length or size, and will vary by type (e.g., common and box nails).
Performance SpecificationStates how a building element must perform as opposed to describing equipment, products or systems by name.
PerliteA lightweight material made from volcanic rock.
PermA unit of measurement of Water Vapor Permenance (ASTM).
PhenolA class of acid organic compounds used in the manufacture of various resins, plastics, and wood preservatives.
PhenolicA synthetic resin made by the reaction of a phenol with an aldehyde.
Photovoltaic CellsThin, flat semiconductors that convert light energy into direct-current electricity.
Physical PropertiesThe properties associated with the physical characteristics of a material, such as thermal expansion and density.
PierA column designed to support a load.
PigAn ingot of cast iron.
Pig IronA high-carbon-content iron produced by the blast furnace and used to produce cast iron and steel.
PigmentsPaint ingredients mainly used to provide color and hiding power.
PilasterProjecting, square column or stiffener forming part of a wall.
PileA wood, steel, or concrete column usually driven into the soil to be used to carry a vertical load.
Pile CapA concrete slab or beam that covers the head of several piles, tying them together.
Pile HammerA machine for delivering blows to the top of a pile, driving it into the earth.
PillarColumn supporting a structure.
Pit, ElevatorThe part of the hoistway that extends below the floor of the lowest landing to the floor at the bottom of the hoistway.
Pitch(1) The slope of a roof or other plane surface.(2) Related to carpets, the number of tufts in a 27-inch width of carpet.
Pitch of RoofSlope of the surface, generally expressed in inches of vertical rise per 12″ horizontal distance, such as “4-in-12 pitch.”
PlasterA cementitious material, usually a mixture of Portland cement, lime or gypsum, sand, and water. Used to finish interior walls and ceilings.
Plaster BaseAny material suitable for the application of plaster.
Plaster of PartsA calcined gypsum mixed with water to form a thick, pastelike mixture.
PlasticAn organic material that is solid in its finished state but is capable of being molded or of receiving form.
Plastic BehaviorThe ability of a material to become soft and formed into desired shapes.
Plastic DeformationThe deformation of a material beyond the point at which it will recover its original shape.
Plastic LiimitRelated to soils, the percent moisture content at which the soil begins to crumble when it is rolled into a thread 1/2 inch (3mm) in diameter.
PlasticityThe ability of a material to be deformed into a different shape.
PlasticizerLiquid material added to some plastics to reduce their hardness and increase pliability. Also, an additive to concrete and mortar to increase plasticity.
Plate“Top” plate is the horizontal member fastened to the top of the studs or wall on which the rafters, joists or trusses rest; “sole” plate is positioned at bottom of studs or wall.
Plate GlassA high-quality glass sheet that has both surfaces ground flat and carefully polished.
PlatformFloor surface raised above the ground or floor level.
Platform FrameA wood structural frame for light construction with the studs extending only one floor high upon which the second floor is constructed.
Platform FramingTechnique of framing where walls can be built and tilted-up on a platform floor, and in multi-story construction are erected sequentially from one platform to another. Also known as “Western” framing.
Plenum(1) The space above a suspended ceiling.(2) Chamber in which the pressure of the air is higher (as in a forced-air furnace system) than that of the surrounding air.
PlyOne of a number of layers in a layered construction.
PlywoodA glued wood panel made up of thin layers of wood veneer with the grain of adjacent layers at right angles to each other or of outer veneers glued to a core of solid wood or reconstituted wood.
Plywood Stressed-Skin PanelA structural panel constructed with outer skins of plywood applied over an internal frame of wood members forming a rigid panel.
Plywood, Cold-PressedInterior type plywood manufactured in a press without external applications of heat.
Plywood, ExteriorPlywood bonded with a type of adhesive that is highly resistant to moisture and heat.
Plywood, InteriorPlywood manufactured for indoor use or in locations in which it would be subject to moisture for only a brief time.
Plywood, MarinePlywood panels with the same glue as exterior plywood but with more restrictive veneer specifications.
Plywood, MoldedPlywood that is glued to the desired shape either between curved forms or by fluid pressure applied with flexible bags or blankets.
Plywood, PostformedPanels formed when flat plywood sheets are reshaped into a curved configuration by steaming or the use of plasticizing agents.
Pole ConstructionConstruction using large-diameter log poles in a vertical position to carry the loads of the floors and roof.
PolycarbonateA polyester made by linking certain phenols through carbonate groups.
PolyesterA linear polymer mad by linear linking of oxybenzoyl units.
PolyethyleneA thermoplastic resin made by polymerizing ethylene.
PolyimideA polymer based on the combination of certain anhydrides with aromatic diamines.
PolymerA chemical compound formed by the union of simple molecules to form more complex molecules.
PolymerizationA chemical reaction in which molecules of a monomer are linked together to form large molecules whose molecular weight is a multiple of that of the original substance.
PolyolefinA polymer composed of open-chain hydrocarbons having double bonds.
PolypropyleneA polymer produced by the linking of repeated propylene monomers.
PolystyreneA clear, colorless plastic resin made by polymerizing styrene.
PolyurethaneA thermoplastic or thermosetting resin derived by the condensation reaction of a polyisocyanate and a hydroxyl.
Polyvinyl ChlorideA thermoplastic resin derived by the polymerizatoin of vinyl and acetate.
PondingThe collection of waters in shallow pools on the top surface of a roof.
PorcelainA strong vitreous material bonded to metal at high temperature.
Porcelain EnamelAn inorganic metal oxide coating bonded to metal by fusion at a high temperature.
Portland CementHydraulic cement produced by pulverizing clinker consisting essentially of hydraulic calcium silicates, usually containing one or more forms of calcium sulfate as an interground addition.
Post, Plank, and Beam FramingA wood-framing system using beams for horizontal structural members that rest on posts, forming the vertical members.
PosttensioningA method used to place concrete under tension in which steel tenons are tensioned after the concrete has been poured and hardened.
PowerThe rate at which work is performed, expressed in watts or horsepower.
PozzolanA siliceous or siliceous and aluminous material blended with portland cement that chemically reacts with calcium hydroxide to form compounds possessing cementitious properties.
Pozzolan CementA cement made from volcanic rock that contains considerable silica.
Precast ConcreteConcrete cast in a form and cured before it is lifted into its intended position.
Prescription SpecificationTraditional procedure used on building projects to describe by name products, equipment or systems to be used.
Pressure-Treated LumberLumber that has chemicals forced into it under pressure to slow decay and provide resistance to fire.
Prestressed ConcreteConcrete that has been pre-tensioned or post-tensioned.
PretensioningA method used to place a concrete member under tension by pouring concrete over steel tendons that are under tension before the concrete is poured.
PrimerA base coat in a paint system. It is applied before the finish coats.
Property LineA legal boundary of a land parcel.
Proportional LimitThe upper limit at which stress is proportional to strain.
PurlinHorizontal member in a roof supporting common rafters, such as at the break in a gambrel roof. Also, horizontal structural member perpendicular to main beams in a flat roof.
QuarryAn open excavation in the earth from which building stone is removed.
Quarry TileA large clay tile used for finished flooring.
QuartersawingSawing lumber so the hard annual rings are nearly perpendicular to the surface.
R-ValueThe numerical value used to indicate the resistance to the flow of heat.
RacewayAn enclosed channel designed to carry wires and cables.
RackingForcing out of plumb of structural components, usually by wind, seismic stress or thermal expansion or contraction.
Radiant HeatHeat transferred by radiation.
RadiationTransfer of heat energy through space by wave motion. Although the radiant energy of heat is transmitted through space, no heat is present until this energy strikes and is absorbed by an object. Not all of the radiant heat energy is absorbed; some is reflected to travel in a new direction until it strikes another object. The amount reflected depends on the nature of the surface that the energy strikes. This fact explains the principle of insulating foil and other similar products that depend on reflection of radiant heat for their insulating value. Radiant heat travels in straight lines in all directions at about the speed of light. In radiant heating systems, heat is often radiated down from the ceiling. As it strikes objects in the room, some is absorbed and some reflected to other objects. The heat that is absorbed warms the object, which, in turn, warms the surrounding air by conduction. This warmed air sets up gentle convection currents that circulate throughout the room.
RafterThat member forming the slanting frame of a roof or top chord of a truss. Also known as hip, jack or valley rafter depending on its location and use.
Rafter TailThat part of a rafter that extends beyond the wall plate — the overhang.
Rainscrean PrincipleThe principle that states that wall cladding can be made watertight by placing wind-pressurized air chambers behind the joints, which reduces the air pressure differentials between the inside and outside that could cause water to move through the joints.
RakeThe board along the sloping edge of a gable.
Ready-Mix ConcreteConcrete mixed in a central plant and delivered to the site by truck.
RebarSteel bar used to reinforce concrete.
Receptacel OutletAn outlet box in which one or more receptacles are installed.
ReceptacleA device installed in an electrical outlet box to receive a plug to supply electric current to portable equipment.
Reduction(1) A process in which iron is separated from oxygen with which it is chemically mixed by smelting the ore in a blast furnace.(2) In regard to aluminum, the electrolytic process used to separate molten aluminum from the alumina.
ReflectanceThe ratio of the intensity of light reflected by a material to the intensity of the incident light.
Reflectance CoefficientA measure stated as a percentage of the amount of light reflected off a surface.
Reflected Coated GlassGlass having a thin layer of a metal or metal oxide deposited on the surface to reflect heat and light.
Reflected HeatSee Radiation.
Reflected SoundSound that has struck a surface and “bounced off.” Sound reflects at the same angle as light reflects in a mirror; the angle of incidence equals the angle of reflection. Large curved surfaces tend to focus (concave) or diffuse (convex) the sound when reflected. However, when the radius of the reflecting surface is less than the wavelength of the sound, this does not hold true. Thus, a rough textured surface has little effect on diffusion of sound.
Reflective InsulationMaterial that reflects and thus retards the flow of radiant heat. The most common type of reflective insulation is aluminum foil. The effectiveness of reflective barriers is diminished by the accumulation of dirt and by surface oxidation.
ReflectivityThe relative ability of a surface to reflect sound or light.
Refractive IndexThe ratio of the speed of light in a material to the speed of light in a vacuum.
RefractoryNonmetallic ceramic material used where high temperatures (above 270 degrees F) are present, such as in furnace linings.
RefrigerantThe medium of heat transfer that absorbs heat by evaporating at low temperatures and pressure and giving up heat when it condenses at a higher temperature and pressure.
Reinforced Brick MasonryBrick masonry construction that has steel reinforcing bars inserted to provide tensile strength.
Relative HumidityThe ratio of the amount of water vapor present in the air to that which the air would hold if saturated at the same temperature.
Remote Control CircuitAn electric circuit that controls any other circuit using a relay or other such device.
ResilianceThe property of a material whereby it gives up its stored energy when deforming force is removed.
ResiliencyThe ability to regain the initial shape after being deformed.
Resilient FlooringFinished flooring made from a resilient material, such as polyvinyl chloride or rubber.
ResinA natural or synthetic material that is the main ingredient of paint and binds the ingredients together.
Resistance, ElectricThe physical property of a conductor or electric-consuming device to resist the flow of electricity, reducing power and generating heat.
Retaining WallA wall that bears against soil or other material and resists lateral and other forces from the material being held in place.
RetarderAn admixture used to slow the setting of concrete.
Return AirAir removed from a space and vented or reconditioned by a furnace, air conditioner, or other apparatus.
ReverberationPersistence of sound after the source stops. When one hears the 10th, 20th, 50th, 100th, etc., reflection of a sound, one hears reverberation.
Reverberation TimeEssentially the number of seconds it takes a loud sound to decay to inaudibility after the source stops. Strictly, the time required for a sound to decay 60 dB in level.
RidgePeak of a roof where the roof surfaces meet at an angle. Also may refer to the framing member that runs along the ridge and supports the rafters.
Rigid FrameA structural framework in which the beams and columns are rigidly connected (no hinged joints).
RiseMeasurement in height of an object; the amount it rises. The converse is “fall.”
RiserVertical face of a step supporting the tread in a staircase.
Riser, PlumbingA water supply running vertically through the building to supply water to the various branches and fixtures on each floor.
RivetA metal fastener used to hold metal plates by passing through holes in each and having a head formed on the protruding end.
Rock AnchorA post-tensioned cable or steel rod inserted into a hole drilled in rock and grouted in place.
RomexA nonmetallic-sheathed electric cable of type NM or NMC.
Roof DrainA drain on the roof to carry away water to a downspout.
Roof PlanksPrecast gypsum concrete members used for decking roofs.
Room Cavity RatioA relationship between the height of a room, its perimeter, and the height of the work surface above the floor divided by the floor area.
Rough FramingStructural elements of a building or the process of assembling elements to form a supporting structure where finish appearance is not critical.
RowsRelated to carpets, the number of tufts per inch.
SabinMeasure of sound absorption of a surface, equivalent to 1 sq. ft. of a perfectly absorptive surface.
SaddleA ridge in a roof deck that divides two sloping parts, diverting water toward roof drains.
SafingFire stop material in the space between floor slab and curtain wall in multi-story construction.
Safing OffInstallation of fire safety insulation around floor perimeters, between floor slab and spandrel panels. Insulation helps retain integrity of fire resistance ratings.
SandstoneA sedimentary rock formed from sand.
Sanitary SewageWaste material containing human excrement and other liquid wastes.
Sanitary SewerA sewer that receives sanitary sewage without the infusion of other water such as rain, surface water, or other clear water drainage.
SapwoodThe wood near the outside of the log just under the bark.
SBCCISouthern Building Code Congress International, nonprofit organization that publishes the Standard Building Code.
ScabSmall piece or block of wood that bridges several members or provides a connection or fastening between them.
Scratch CoatThe first coat of gypsum plaster that is applied to the lath.
ScreedA tool used to strike off the surface of freshly poured concrete so it is flush with the top of the form.
ScreedingThe process of striking off the surface of freshly poured concrete with a screed so it is flush with the top of the form.
ScupperAn outlet in a parapet wall for the drainage of overflow water from the roof to the outside of a building.
ScuttleAn opening through the ceiling and roof to provide access to the roof. It is covered with a waterproof cover. Also referred to as a roof hatch.
SealantA mastic used to seal joints and seams.
SealerA material used to seal the surface of a material against moisture.
SeasoningRemoving moisture from green wood.
Seated ConnectionsConnections that join structural steel members with metal connectors, such as an angle upon which one member, such as a beam, rests.
Section Modulus (S)Numerical relationship, expressed in in.3, of the resistance to stress of a member. It is equal to the moment of inertia divided by the perpendicular distance from the neutral axis to the extremity of the member.
Security GlassGlass panels assembled with multiple layers of glass and plastic to produce a panel that will resist impact.
Sedimentary RockRock formed from the deposit of sedimentary materials on the bottom of a body of water or on the surface of the earth.
SegregationThe tendency of large aggregate to separate from the sand-cement mortar in the concrete mix.
Seismic AreaA geographic area where earthquake activity may occur.
Seismic LoadForces produced on a structural mass by the movements caused by an earthquake.
SemitransparentCoatings that allow some of the texture and color of the substrate to show through.
Sensible HeatHeat that causes a detectable change in temperature.
Septic TankA watertight tank into which sewage is run and where it remains for a period of time to permit hydrolysis and gasification of the contents, which then flow from the tank and are absorbed in the soil.
Service EntranceThe point at which power is supplied to a building and where electrical service equipment, such as the service switch, meter overcurrent devices, and raceways, are located.
Service EquipmentThe equipment needed to control and cut off the power supply to a building, such as switches and circuit breakers.
Service TemperatureThe maximum temperature at which a plastic can be used without altering its properties.
ShadowingAn undesirable condition where the joint finish shows through the surface decoration.
Shaft WallFire-resistant wall that isolates the elevator, stairwell and vertical mechanical chase in high-rise construction. This wall must withstand the fluctuating (positive and negative) air-pressure loads created by elevators or air distribution systems.
ShalesClays that have been subjected to high pressures, causing them to become relatively hard.
shared-party-wallA wall built on the dividing line between two adjoining parcels, in which each owner has an equal share of ownership.
ShearForce that tends to slide or rupture one part of a body from another part of the body or from attached objects.
Shear PanelA floor, wall, or roof designed to serve as a deep beam to assist in stabilizing a building against deformation by lateral forces.
Shear Plate ConnectorA circular metal connector recessed into a wood member that is to be bolted to a steel member.
Shear StressThe result of forces acting parallel to an area but in opposite directions, causing one portion of the material to “slide” past another.
Shear StudsMetal studs welded to a steel frame that protrude up in the cast-in-place concrete deck.
SheathingPlywood, gypsum, wood fiber, expanded plastic or composition boards encasing walls, ceilings, floors and roofs of framed buildings. May be structural or non-structural, thermal-insulating or non-insulating, fire-resistant or combustible.
SheaveA pully over which the elevator wire hoisting rope runs.
SheetingWood, metal, or concrete members used to hold up the face of an excavation.
SHEETROCKLeading brand of gypsum panel for interior wall and ceiling surfaces, developed and improved by United States Gypsum Company. There is only one SHEETROCK brand Gypsum Panel.
Shop DrawingsRelated to steel construction, working drawings giving the information needed to fabricate structural steel members.
ShoringTemporary member placed to support part of a building during construction, repair or alteration; also may support the walls of an excavation.
Shrinkage LimitRelated to soils, the water content at which the soil volume is at its minimum.
Siamese ConnectionA connection outside a building to which firefighters connect an alternate water supply to boost the water used by the fire suppression system.
SillHorizontal member at the bottom of a door or window frames to provide support and closure.
Sill PlateHorizontal member laid directly on a foundation on which the framework of a building is erected.
SiltFine sand with particles smaller than 0.002 inches (0.05 mm) and larger than 0.00008 inches (0.002 mm).
Single-Ply RoofingA roofing membrane composed of a sheet of water-proof material secured to the roof deck.
SinteringA process that fuses iron-ore dust with coke and fluxes into a clinker.
Site InvestigationAn investigation and testing of the surface and subsoil of the site to record information needed to design the foundation and the structure.
Site PlanA drawing of a construction site, showing the location of the building, contours of the land, and other features.
Site-Cast ConcreteConcrete poured and cured in its final position.
SkylightA roof opening that is covered with a watertight transparent cover.
SlabFlat (although sometimes ribbed on the underside) reinforced concrete element of a building that provides the base for the floor or roofing materials.
Slab-On-GradeA concrete slab poured and hardened directly on the surface of the earth.
SlagA molten mass composed of fluxes and impurities removed from iron ore in the furnace.
SlakeThe process of adding water to quicklime, hydrating it and forming lime putty.
Slip FormA form designed to move upward as concrete is poured in it.
SlumpA measure of the consistency of freshly mixed concrete, mortar, or stucco.
Slump TestA test to ascertain the slum of concrete samples.
SlurryA liquid mixture of water, bentonite clay, or Portland cement.
Slurry WallA wall built of a slurry used to hold up the sides of an area to be excavated.
SmeltingA process in which iron ore is heated, separating the iron from the impurities.
Smoke BarriersContinuous membranes used to resist the passage of smoke.
Smoke Developed RatingA relative numerical classification of the fumes developed by a burning material.
SoffitUndersurface of a projection or opening; bottom of a cornice between the fascia board and the outside of the building; underside of a stair, floor or lintel.
Soft-Mud ProcessA process used to make bricks when the clay contains moisture in excess of 15 percent.
SoftwoodA botanical group of trees that have needles and are evergreen.
Soil AnchorsMetal shafts grouted into holes drilled into the sides of an excavation to stabilize it.
Soil StackA vertical plumbing pipe into which waste flows through waste pipes from each fixture.
Soil VentThat portion of a soil stack above the highest fixture waste connection to it.
Solar EnergyRadiant energy originating form the sun.
Solar ScreenA device used to divert solar energy form windows.
Sole PlateSee Plate.
Solid Clay MasonryA unit whose core does not exceed 15 percent of the gross cross-sectional area of the unit.
SolventsLiquids used in paint and other finishing materials that give the coating workability and that evaporate, permitting the finish material to harden.
Sound AbsorptionConversion of acoustic or sound energy to another form of energy, usually heat.
Sound Insulation, IsolationUse of building materials or constructions that will reduce or resist the transmission of sound.
Sound IntensityAmount of sound power per unit area.
Sound Pressure Level (SPL)Expressed in decibels, the SPL is 20 times the logarithm to the base 10 of the ratio of the sound pressure to a reference pressure of 20 micropascals. See Decibel.
Sound Transmission Class (STC)Single-number rating for evaluating the effectiveness of a construction in isolating audible airborne sound transmission across 16 frequencies. Higher numbers indicate more effectiveness. Tested per ASTM E90.
SpanDistance between supports, usually a beam or joist.
Span RatingNumber indicating the distance a sheet of plywood or other material can span between supports.
Spandrel BeamHorizontal member, spanning between exterior columns, that supports the floor or roof.
Spandrel WallExterior wall panel, usually between columns, that extends from the window opening on one floor to one on the next floor.
Special UnitsConcrete masonry units that are designed and made for a special use.
Specific AdhesionBonding dense materials using the attraction of unlike electrical charges.
Specific GravityThe ratio of the weight of one cubic foot of a material to the weight of one cubic foot of water.
SpecificationsA written document in which the scope of the work, materials to be used, installation procedures, and quality of workmanship are detailed.
Speed of SoundVaries with atmospheric pressure and temperature, but is the same at all frequencies. For most architectural work, the speed of sound should be taken as 1,130 ft./second.
SpireA tall pyramidal roof built upon a tower or steeple.
Split Ring ConnectorA ring-shaped metal insert placed in circular recesses cut in joining wood members that are held together with a bolt or lag screw.
Spoil BankAn area where soil from the excavation is stored.
Spread FoundationA foundation that distributes the load over a large area.
Spreading RateThe area over which a paint can be spread expressed in square feet per gallon.
SquareIn roofing, 100 square feet of roofing material.
StabilizersAdditives used to stabilize plastic by helping it resist heat, loss of strength, and the effect of radiation on the bonds between the molecular chains.
StainA solution of coloring matter in a vehicle used to enhance the grain of wood during the finishing operation.
Stained-Glass WindowA window made of small colored glass pieces joined with leaded canes.
Standing SeamThe vertical seam formed when two sheets of metal roofing are joined.
Static LoadsAny load that does not change in magnitude or position with time.
SteamWater in a vapor state.
Steam SeparatorA device used to remove moisture from steam after it flows from the boiler.
Steam TrapA device used to allow the passage of condensate while preventing the passage of steam.
SteelA malleable alloy of iron and a small carefully controlled carbon content.
Steep-Slope RoofsRoof with sufficient slope to permit rapid runoff of rain.
SteepleA towerlike ornamental construction, usually square or hexagonal, placed on the roof of a building and topped with a spire.
Stiff-Mud ProcessA process used to make bricks from clay that has 12 to 15 percent moisture.
StiffnessResistance to bending or flexing.
StileVertical outside member in a piece of mill work, as a door or sash.
StirrupHanger to support the end of the joist at the beam.
StoneRock selected or processed by shaping to size for building or other use.
StopStrip of wood fastened to the jambs and head of a door or window frame against which the door or window closes.
StrainUnit deformation in a body that results from stress.
Strain HardeningIncreasing the strength of a metal by cold-rolling.
Strand-Casting MachineA machine that casts molten steel into a continuous strand of metal that hardens and is cut into required lengths.
StressUnit resistance of a body to an outside force that tends to deform the body by tension, compression or shear.
Stress-Rated LumberLumber that has its modulus of elasticity determined by actual tests.
Stressed-Skin PanelsAn assembly with high-strength facing panels separated by wood spacing strips and bonded firmly to them.
StringerHeavy horizontal timber supporting other members of the frame in a wood or brick structure; a support also for steps.
Structural Clay Facing TileHollow clay units used in bearing and non-bearing walls that have cores exceeding 25 percent of the gross cross sectional area.
Structural Sandwich ConstructionA wood construction consisting of a high-strength facing material bonded to and acting integrally with a low-density core material.
Structure-borne SoundSound energy imparted directly to and transmitted by solid materials, such as building structures.
StrutSlender structural element that resists compressive forces acting lengthwise.
StuccoA Portland cement plaster used as the finish material on building exteriors.
StudVertical load-bearing or non-load bearing framing member.
SubfloorRough or structural floor placed directly on the floor joists or beams to which the finished floor is applied. As with resilient flooring, an underlayment may be required between subfloor and finished floor.
SubstrateUnderlying material to which a finish is applied or by which it is supported.
Suction RateThe weight of water absorbed when a brick is partially immersed in water for one minute expressed in grams per minute or ounces per minute.
Suction, Clay MasonryThe rate at which clay masonry units absorb moisture.
SuperplasticizerAn admixture used with concrete to make the wet concrete very fluid without adding additional water.
Supply AirConditioned air entering a space from a heating, ventilating, or air-conditioning (HVAC) unit.
Surface Burning CharacteristicRating of interior and surface finish material providing indexes for flame spread and smoke developed, based on testing conducted according to TOP.
Surface Burning RatingThe rating of interior and surface finish material providing indexes for flame spread and smoke.
Surface ClaysClays obtained by open-pit mining.
Surface EffectThe effect caused by the entrainment of secondary air against or parallel to a wall or ceiling when an outlet discharges air against or parallel to the wall or ceiling.
Suspended CeilingA finish ceiling hung from the overhead by a series of wires.
Switch, Bypass IsolationA manually operated switch used in connection with a transfer switch to provide a means of directly connecting load conductors to a power source and for disconnecting the transfer switch.
Switch, General-UseA switch used for general electrical control.
Switch, General-Use SnapA general-use switch built so it can be installed in a device box or on the box cover.
Switch, IsolatingA switch used to isolate an electric circuit from the source of power.
Switch, Motor-ControlA switch used to interrupt the maximum operating overload current of a motor.
Switch, TransferA device used to transfer one or more conductors from one power source to another.
SwitchboardA large single panel or an assembly of panels with switches, overcurrent protection devices, and buses that are mounted on the face or both sides of the panel.
SwitchesDevices to open and close an electric circuit or to change the connection within a circuit.
Synthetic FibersFibers formed by chemical reactions.
Synthetic MaterialsMaterials formed by the artificial building up of simple compounds.
T-SillA type of sill construction used in balloon framing in which the header joist is placed inside the studs and is butted by the floor joists.
TapestryA fabric upon which colored threads are woven by hand to produce a design.
TeePrecast concrete or metal structural members in the shape of the letter T.
Temper DesignationA specification of the temper or metallurgical condition of an aluminum alloy.
TemperatureMeasurement of the intensity (not quantity) of heat. The Fahrenheit (°F) scale places the freezing point of water at 32° and the boiling point at 212°. The Centigrade or Celsius (°C) scale, used by most countries and in scientific work, places the freezing point of water at 0° and the boiling point at 100°. On the Kelvin (K) scale, the unit of measurement equals the Celsius degree and measurement begins at absolute zero 0° (-273°C).
Tempered GlassHeat-treated glass that has great resistance to breakage and increased toughness.
TemperingThe reheating of hardened steel to decrease hardness and increase toughness.
Tempering GlassA process used to strengthen glass by raising the temperature of the glass to near the softening point and then blowing jets of cold air on both sides suddenly to chill it and create surface tension in the glass.
TendonA steel bar or cable in prestressed concrete used to impart stress in the concrete.
Tensile Bond StrengthThe ability of a mortar to resist forces tending to pull the masonry apart.
Tensile StrengthMaximum tensile stress that can be developed in a given material under axial tensile loading. Also the measure of a material’s ability to withstand stretching.
Tensile StressThe stress per unit area of the cross-section of a material that resists elongation.
TensionForce that tends to pull the particles of a body apart.
Terra-CottaA hard unglazed clay tile used for ornamental work.
TerrazzoA finish-floor material made up of concrete and an aggregate of marble chips that after curing is ground smooth and polished.
Texture PlasterA finish plaster used to produce rough, textured finished surfaces.
Thermal BreakMaterial with a low thermal conductivity that is inserted between materials, such as metal with high thermal conductivity, to slow the passage of cold or heat through the highly conductive material.
Thermal BridgeA thermal conducting material that conducts heat through an insulated assembly of materials.
Thermal Conductance (C)Thermal conductance is the same as thermal conductivity except it is based on a specified thickness of material rather than on one inch as used for conductivity.
Thermal ConductionThe process of heat transfer through a solid by transmitting kinetic energy from one molecule to the next.
Thermal Conductivity (k)The rate of heat flow through one square foot of Btu per hour when a temperature difference of one degree Fahrenheit is maintained between the two surfaces.
Thermal ConvectionHeat transmission by the circulation of a liquid or heated air or gas.
Thermal ExpansionAll materials expand and contract to some extent with changes in temperature. The Thermal Coefficient of Linear Expansion is expressed in “Inches Per Inch Per Degree Fahrenheit.” Example: gypsum board has a coefficient of 9.0 x 10-6 in. per in. per °F. This means that with an increase in temperature of 50°, a gypsum board wall 100 ft. in length will have a linear expansion of .54″ or an excess of 1/2″. The expansion characteristics of some other building materials are more pronounced; a 50° temperature increase would produce expansion in a 100′ length of approx. 3/4″ in aluminum, 3/8″ in steel and 1/2″ in concrete.
Thermal InsulationA material that has a high resistance to heat flow.
Thermal PropertiesThe behaviour of a material when subjected to a change in termperature.
Thermal RadiationThe transmission of heat from a hot surface to a cool one by means of electromagnetic waves.
Thermal Resistance (R)Resistance of a material or assembly to the flow of heat. It is the reciprocal of the heat transfer coefficient: (1/C, or 1/U)For insulating purposes, low “C” and “U” values and high “R” values are the most desirable.
ThermoformingA process in which heated plastic sheets are made to assume the contour of a mold by using the force of air pressure, vacuum, or mechanical stretching.
ThermoplasticsPlastics that soften by heating and reharden when cooled without changing the chemical composition.
Thermosetting PlasticsCured plastics that are chemically cross-linked and when heated will not soften but will be degraded.
ThermostatA temperature-sensitive instrument that controls the flow of electricity to units used to heat and cools spaces in a building.
ThresholdRaised member at the floor within the door jamb. Its purpose is to provide a divider between dissimilar flooring materials or serve as a thermal, sound or water barrier.
Through-penetration Fire StopA system for sealing through-penetrations in fire-resistant floors, walls and ceilings.
Through-penetrationsThrough-penetration, or “poke-through” openings as they are sometimes called, are holes that penetrate an entire floor or wall assembly to allow the passage of piping, ducts, conduit, cable trays, electrical cables, communications wiring, etc.
ThrowThe horizontal or vertical distance an airstream travels after leaving the air outlet before it loses velocity.
Tieback AnchorsSteel anchors grouted into holes drilled in the excavation wall to hold the sheeting, thus reducing the number of braces required.
TimberWood structural members having a minimum m thickness of 6 inches (140 mm).
Timber JoineryThe joining of structural wood members using wood joints, such as the mortise and tenon.
Time-Temperature CurveRate of rise of temperature in a fire-testing furnace.
ToenailMethod of fastening two boards together as in a “T” by driving nails into the board that forms the stem of the “T” at an angle so they enter the other board and cross each other.
ToleranceThe permissible deviation from a given dimension or the acceptable variation in size from the given dimension.
Tongue-and-Groove JointJoint where the projection or “tongue” of one member engages the mating groove of the adjacent member to minimize relative deflection and air infiltration; widely used in sheathing, flooring and paneling. Tongues may be in “V,” round or square shapes.
TopcoatThe final coat of paint.
TorqueA twisting or rotating action.
Torsion StrengthThe maximum stress a material will withstand before fracturing under a twisting force.
Torsion TestA test used to ascertain the behavior of materials subject to torsion.
ToughnessA measure of the ability of a material to absorb energy from a blow or shock without fracturing.
TransformerAn electrical device used to convert an incoming electric current from one voltage to another voltage.
Transmission Loss (TL)Essentially the amount, in decibels, by which sound power is attenuated by passing from one side of a structure to the other. TL is independent of the rooms on each side of the structure and theoretically independent of the area and edge conditions of the structure.
TrapA device used to maintain a water seal against sewer gases that back up the waste pipe. Usually, each fixture has a trap.
TreadHorizontal plane or surface of a stair step.
TrimmerDouble joists or rafters framing the opening of a stairway well, dormer opening, etc.
TrowelingProducing a final smooth finish on freshly poured concrete with a steel-bladed tool after the concrete has been floated.
TrussOpen, lightweight framework of members, usually designed to replace a large beam where spans are great.
Truss PlateA steel plate used to strengthen the joints in truss assemblies.
Truss-Framed SystemAn assembled truss uint made up of a floor truss, wall stud, and a roof truss.
Tufted ConstructionCarpet formed by stitching the pile yarn through the backing material.
TwistWarping in which one or more corners of a piece o wood twist out of the plane of the piece.
Two-Way Concrete Joist SystemFloor and roof construction that has two perpendicular systems of parallel intersecting joists.
Two-Way Flat PlateReinforced concrete construction in which the main reinforcement runs in two directions and both surfaces are flat planes and it is supported by columns.
Two-Way Flat SlabReinforced concrete floor or roof construction in which a two-way flat plate is supported by columns with drop panels or column capitals.
U of CUniversity of California, an independent fire-testing laboratory.
U ValueCoefficient of heat transfer, “U” equals 1 divided by (hence, the reciprocal of) the total of the resistances of the various materials, air spaces and surface air films in an assembly. See Thermal Resistance.
UBCUniform Building Code – document promulgated by the International Conference of Building Officials.
ULUnderwriters Laboratories Inc., founded by NBFU, and now operated in affiliation with American Insurance Assn. UL is a not for profit laboratory operated for the purpose of testing devices, systems and materials as to their relation to life, fire and casualty hazard in the interest of public safety.
Ultimate StrengthThe maximum stress, such as tensile, compressive, or shear, that a material can withstand.
Ultimate Tensile StrengthThe maximum tensile stress of a material up to the point of rupture.
Ultrasonic TestingA method of non-destructive testing of materials that uses high frequency sound vibrations to find defects in the material.
Under-Carpet WiringA flat, insulated electric wire that is run under the carpet.
UnderlaymentSheet material, such as hardboard, that is laid over the subfloor to provide a smooth, stiff surface for the finish flooring.
UnderpinningPlacing a new foundation below the existing foundation.
Unfibered GypsumA neat gypsum. It has no additives.
Uniform LoadAny load that is spread out evenly over a large area.
Unreinforced ConcreteConcrete placed without steel-reinforcing bars or welded-wire fabric.
USASIUnited States of America Standards Institute, now American National Standards Institute.
ValenceThe points on an atom to which valences of other elements can bond.
ValleyThe intersection of two inclined surfaces.
Vapor RetarderMaterial used to slow the flow of water vapor through walls and other spaces where this vapor may condense at a lower temperature.
VarnishA thin sheet of material used to cover another surface.
VehicleThe liquid portion of a paint composed mainly of solvents, resins, or oils.
Velvet ConstructionCarpet formed by joining the pile, stuffer, and weft yarns with double warp yarns.
VeneerA thin sheet of material used to cover another surface.
Veneer Gypsum BaseA gypsum board product designed to serve as the base for the application of gypsum veneer plaster.
Veneer PlasterCalcined gypsum plaster specially formulated to provide specific workability, strength, hardness and abrasion resistance characteristics when applied in thin coats (1/16″ to 3/32″ nom.) over veneer gypsum base or other approved base. The term thin coat plaster is sometimes used in reference to veneer plaster.
Vent StackThat part of the soil stack above the highest vent branch.
Vents, PlumbingPipes permitting the waste system to operate under atmospheric pressure. They allow air to enter and leave the system, preventing water in the traps from being siphoned off. If this occurs, sewer gases can enter the building.
VermiculiteAn insulation material or aggregate made of expanded mica.
Vertical LoadA load acting in a direction perpendicular to the plane of the horizon.
Vertical ShearThe tendency of one part of a member to move vertically in relationship to the adjacent part.
ViscosityThe resistance of a liquid to flow under an applied load or pressure.
VitrificationA process of using high kiln temperatures to fuse the surface of grains of clay products so they are impervious to the passage of water.
Volatile Organic CompoundsCompounds released to the atmosphere as a coating dries.
VoltThe unit of potential difference or electromotive force. One volt applied across a resistance of one ohm results in a current flow of one ampere.
VoltageThe force, pressure, or electromotive force that causes electric current to flow in an electric circuit.
WaferboardA mat-formed panel made of wood wafers randomly arranged and bonded with a waterproof binder.
Wafle SlabA concrete slab that has ribs running in two directions forming a waffle-like grid.
WainscotA protective or decorative finish wall covering applied to the lower part of an interior wall.
WarpA variation in a board from a flat, plane condition.
Waste PipeHorizontal plumbing pipes that connect a fixture to the soil pipe.
Water RepellentLiquid that penetrates the pores of wood and prevents moisture from penetrating without altering the desirable qualities of the wood.
Water RetentionThe property of a mortar that prevents the rapid loss of water by absorption into the masonry units.
Water StopA rubber or plastic diaphragm placed across a joint in cast concrete to prevent the passage of water through the joint.
Water TableThe level below the ground where the soil is saturated with water.
Water-Based CoatingsCoatings formulated with water as the solvent.
Water-Cement RatioIn a concrete or mortar mixture, the ratio fo the amount of water (minus that held by the aggregates) to the amount of cement used.
Water-SmokingA process used to drive off the remaining water from clay products before they are fired in the kiln.
Water-Struck BrickBrick made in a mold that was wetted before the clay was placed in the mold.
Water-Vapor PermeabilityThe rate of water-vapor transmission through a given area of flat material of a given thickness induced by a given vapor pressure difference between the two surfaces under specified temperature and humidity conditions.
Water-Vapor Transmission RateThe steady-state vapor flow in a given time through a given area of a body, normal to specified parallel surfaces, under specific conditions of temperature and humidity at each surface.
WaterproofingA material used to make a surface impervious to the penetration of water.
WattThe unit of measurement of electrical power or rate of work. It is a pressure of one volt flowing at the rate of one ampere.
Wavelength (Sound)Wave is one complete cycle of sound vibration passing through a medium (such as air) from compression through rarefaction and back to compression again. The physical length of this cycle is termed the wavelength. Wavelengths in air vary from about 1&1/16″ for a 20,000-cycle per sec. (see Frequency) sound, to approximately 56&1/2′ for a 20-cycle per sec. sound — the two approximate extremes of human hearing sensitivity. There are waves outside of this range, but generally, they cannot be heard by humans.
WeatherabilityThe ability of a plastic to resist deterioration due to moisture, ultraviolet light, heat, and chemicals found in the air.
Weathered JointA mortar joint finished so the mortar slopes outward, allowing water to shed away from the joint.
WeatheringChanges in the strength, color, surface, or other properties of a material due to the action of the weather.
Weathering IndexA value that reflects the ability of clay masonry units to resist the effects of weathering.
Weathering SteelA steel alloy that forms a natural self-protecting rust.
Weep HoleSmall openings at the bottom of exterior cavity walls to allow moisture in the cavity to drain out.
Welded-Wire FabricA form of steel reinforcing made from wire strands welded where they cross, forming a mesh.
Wet SandTo smooth a finished joint with a small-celled wet sponge. A preferred method to reduce dust created in the dry sanding method.
WHIWarnock Hershey International, an independent fire-testing laboratory.
Wilton ConstructionCarpet formed on a loom capable of feeding yarns of various colors.
Wind LoadAny load on a building caused by pressure or suction developed by the wind.
Wind UpliftUpward forces on a building caused by pressure or suction developed by the wind.
Window WallA type of metal curtain wall composed of metal framing members containing operable sash, fixed lights, ventilators, or opaque glass panels.
WinningA term used to describe the mining of clay.
Wired GlassGlass made with a wire grid embedded in it.
Wood PreservativeSubstance that is toxic to fungi, insects, borers, and other wood-destroying organisms.
Workability(1) Describes the ease or difficulty with which concrete can be placed and worked into its final location.(2) In relation to mortar, the property of freshly mixed mortar that determines the ease and homogeneity with which it can be spread and finished.
Working JointsJoints in exterior walls that allow for expansion and contraction of materials in the wall.
WrackingWhen a building component, such as a wall, is forced out of plumb.
Wrought ProductsProducts formed by any of the standard manufacturing processes, such as drawing, rolling, forging, or extruding.
Xeriscape IrrigationSystem used to water drought tolerant landscapes and other xeriscape environments where water efficiency is necessary. The most commonly used system is drip irrigation.
Xeriscape PlantsDrought tolerant or low water use plants used in xeriscape landscapes and gardens.
XeriscapingLandscaping that thrives with little or no water. In addition to reducing water consumption, xeriscaping reduces waste, maintenance, costs, and fertilizer use.
YardWith regards to zoning, an open, unoccupied space on all sides of a building, based on the required setbacks.
Yield PointThe point at which strains increase without a corresponding increase in stress.
Yield StrengthThe load at which a limited permanent deformation occurs.
ZoneArea established by a governing body for specific use, such as residential, commercial, or industrial use.
Zone of AerationThe zone below the ground in which all of the spaces between soil grains contain both water and air.
Zone of SaturationThe zone below the ground in which all of the spaces between soil grains are filled completely with water.
ZoningThe legal means whereby land use is regulated and controlled for the general welfare.
Zoning OrdinancesLocal regulations that control the use and development of land.