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Construction terms

Glossary

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

A

Abutment Piece or Member - The bearing plate or piece of a wall system to which the loads are transferred

Accordion Folding Door - A folding, hinged or creased door with rollers which run along a track

Adobe - Unburned or unfired brick, dried in the sun

Air Cleaning - A control strategy to remove various airborne particulate and/or gases from the air. The three types of air cleaning most commonly used are particulate filtration, electrostatic precipitation, and gas absorption.

Air-To-Air Heat Exchanger - A method of heat recovery in which the intake and exhaust ducts are brought together at the heat exchanger

Arbitration - A proceeding for resolution of disputes in which a neutral person, after hearing both sides, makes a final and binding decision that resolves the dispute. A hearing is used to resolve disputes.

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

As Builts - A set of drawings prepared by the general contractor which includes any revisions in the working drawings and specifications during construction, indicating how the project was actually constructed.

B

Back Splash - A protective panel installed behind a counter, sink, or lavatory.

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

Barrier, Vapor - A type of plastic sheeting that both eliminates drafts and keeps moisture from damaging a building or structure.

Beam - A straight structural member that acts primarily to resist transverse loads. A structural element which sustains transverse loading and develops internal forces of bending and shear in resisting the loads. An inclusive term for joints, girders, rafters, and purlins.

Bearing Wall - A wall which supports any vertical loads in addition to its own weight.

Board Foot - A unit of lumber volume, a rectangular solid nominally 12" x 12" x 1". The equivalent of a board 1-foot square and 1 inch thick.

Brushed Surface - A sandy texture obtained by brushing the surface of freshly placed or slightly hardened concrete with a stiff brush for architectural effect or, in pavements to increase skid resistance.

Building Envelope - Elements of the building, including all external building materials, windows, and walls, that enclose the internal space.

Building Paper - Water repellant paper used to assist in shedding incidental moisture what may penetrate exterior finishes of exterior wall construction. Thick paper, used to insulate a building before the siding or cladding is installed. Occasionally used in floor between double floors.

C

Cantilever - A structural shape (beam, truss, or slab) that extends beyond its last point of support.

Cement - Usually refers to Portland cement which when mixed with sand, gravel, and water forms concrete. Generally, cement is an adhesive; specifically, it is that type of adhesive which sets by virtue of a chemical reaction.

Ceramic tile - A ceramic surfacing unit, usually relatively thin in relation to facial area, made from clay or a mixture of clay; and other ceramic material, called the body of the tile, having a "glazed" or "unglazed" face, and fired above red heat in the course of manufacture to a temperature sufficiently high to produce specific physical properties and characteristics.

Change order - An order to change the work to be performed under a construction contract, usually given by an owner to a prime contractor or by a prime contractor to a subcontractor. A revision in the contract documents after the execution of the owner-contractor contract.

Condenser - A heat exchanger in a refrigeration cycle used to discharge heat to the outside. Three commonly used types of condensers can be classified as water-cooled, air cooled, and evaporative. Condenser water is normally circulated through a cooling tower through which heat is distributed to the atmosphere. A heat exchanger in a refrigeration cycle used to discharge heat to the outside.

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

Cornice - The exterior detail at the meeting of a wall and a roof overhang; a decorative molding at the intersection of a wall and ceiling. The molded projection which finishes the top of the wall of a building.

Cross Brace - Bracing with two intersecting diagonals. Slender diagonal member within framed wall or partition, to support wall or partition and to withstand structural loads imposed by wind and suction loads, building loads, movement and deflection of structure.

Curing - Maintenance of humidity and temperature of freshly placed concrete during some definite period following placing, casting, or finishing to assure satisfactory hydration of the cementitious materials and proper hardening of the concrete. The hardening of concrete or plaster.

D

Dehumidifier - A machine that removes moisture from the air.

Diffuser - A device for distributing air in a forced air heating/cooling system. Often flush-mounted on a ceiling, it has slats to direct the conditioned air evenly into the room or space. Components of the ventilation system that distribute and diffuse air to promote air circulation in the occupied space. A lens in a light fixture to diffuse light

Distribution Panel - The main electrical control center, which contains switches or circuit breakers, is connected to the service wires and delivers current to the various branch circuits.

Dormer - An appendage to a roof, a small opening in a roof, which provides ventilation and light to an attic area. Several shapes are common, gable-ended dormer, shed dormer, and hip dormer.

Double Hung Window - The most common style of operable window. It has two sashes that slide vertically in parallel tracks. A window with two overlapping sashes that slide vertically in tracks.

Downspout - The vertical part of a drainage system from a roof-which forms a channel or pipe to remove water from the gutters.

Drain Tile - Short-Length section of burned clay, plastic, or concrete pipe laid with open joints and surrounded with aggregate and covered with asphaltic paper or straw to drain water from an area.

Drapery track - a U-shaped device mounted to a door or window header, ceiling or floor, used as a guide for draperies.

Drip edge - A discontinuity or strip installed at roof eaves or over a window or wall component to force adhering drops of water to fall free of the face of the building rather than move farther toward the interior. The projection of a window header or water table to allow the water to drip clear of the side of the building below it.

Drywall - An interior facing panel consisting of a gypsum core sandwiched between paper faces, also called gypsum board or plasterboard. Different types are available for standard, fire-resistant, water-resistant, and other applications.

E

Easement - A right to utilize real property owned by another. An interest in land owned by another that entitles its holder to a specific limited use.

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

Edger - A finishing tool used on the edges of fresh concrete to provide a rounded corner.

Electric Heating - A system that imparts heat or holds something to be heated, controlled by electric current.

Elevated Slab - A roof slab or floor supported by structural members.

Enamel Paint - A paint which dries to a hard gloss or semi-gloss smooth finish.

End Truss - A factory made wooden truss which is used at the gable end of a building and to which the sheathing and siding are fastened.

Etch - The art of producing designs on metal or glass by the use of corrosive action of an acid. The use of acid to cut lines into metal or remove the surface of concrete.

Expansion Joint - A joint through tile, mortar, concrete or masonry down to the substrate, intended to allow for gross movement due to thermal stress or material shrinkage.

Exterior Door - a door which is manufactured to withstand the elements and vandalism, so it can be installed on the exterior of a building.

F

Façade - An exterior face of a building.

Fascia - A flat, vertical face member or band at the surface of a building or the edge beam of a bridge, or exposed eaves of a building; often inappropriately called fascia. A flat member of a cornice or other finish; generally the board of the cornice to which the gutter is fastened.

Fink Truss - A three triangle symmetrical truss, commonly used in supporting large, large roofs.

Fire Resistant - Incombustible or slow to be damaged by fire; forming a barrier to the passage of fire.

Fire Retardant - Denotes a reduction in the flammability and in the spread of fire. Applied or pressurized chemical treatment to retard combustion.

Flashing - A thin, continuous sheet of metal, plastic, rubber or waterproof paper used to prevent the passage of water through a joint in a wall, roof, or chimney. The material used and the process of making watertight the roof intersections and other exposed places on the outside of a structure.

Flue - A passage for smoke and combustion products from a furnace, stove, water heater or fireplace. The opening in a chimney through which smoke exits.

Footing - The widened base of a foundation that spreads a load from the building across a broader area of soil. An enlargement at the lower end of a wall, pier, or column, used to distribute the load.

Foundation - The portion of a building that has the sole purpose of transmitting structural loads from the building into the earth. That part of a building or wall which supports the superstructure.

Frame - A structural system consisting of relatively long, prismatic members fastened together. A rigid frame is one in which the joints can transmit moments as well as forces and which therefore does not require a braced frame for rigidity. The surrounding or enclosing woodwork of windows, doors, etc., the timber skeleton of the building.

G

Gable - The triangular wall beneath the end of a gable roof. The vertical triangular end of a building from the eaves to the apex of the roof.

Galvanized - Zinc plated for corrosion protection achieved by hot dipping into molten zinc or by electrolysis.

Gambrel - A symmetrical roof with two different pitches or slopes on each side.

Geodesic Dome - A dome constructed according to the patents of R. Buckminster Fuller, in which the pattern of surface divisions is always a function of an entire sphere. Commonly constructed with prefabricated structural triangles linked together in a mosaic to create the domed shape.

Grab Bar - Metal or plastic bar attached to a bathroom wall, above a bathtub, near a toilet, or in a shower, to be used as a handhold.

Grade - A predetermined degree of slope that a finished floor or ramped surface should have. The horizontal ground level of a building or structure.

Grounding - The act or process of making an electrical connection with the earth. A large conduction body used as a common return for an electrical circuit.

Grout - A rich or strong cementitious or chemically setting mix used for filling masonry or tile joints/voids. A mixture of Portland cement, aggregates, and water, which can be poured or pumped into cavities in concrete or masonry.

Gutter - A channel to collect water and snow melt at the eaves of a roof. A shallow channel constructed of steel, copper, aluminum, or plastic compounded with other materials to increase strength and wearing and rust resistance, positioned just below and along the eaves of a building for collecting and diverting water from a roof.

Gypsum - Hydrous calcium sulfate. The main component of sheetrock or drywall.

H

H Beam - A steel beam which in cross section resembles the letter "H". Commonly used in earthwork as a retaining structure or piling.

Halide Fixture - An electric discharge light fixture that makes its light from metal vapor such as sodium or mercury.

Hardwood Plywood Panel - Plywood with face plies manufactured from hardwood (deciduous tress with broad-leaved trees) species such as cherry, oak, birch, ash, walnut, gum, mahogany, or teak.

Header - A lintel. A joist that supports other joists. A short joist into which the common joists are framed around or over an opening. A structural support over an opening.

Heat Pump - A unit that supplies heating or cooling to an interior space by either absorbing heat from or rejecting heat to the outside.

Heavy Timber - Construction requiring noncombustible exterior walls with a minimal fire resistance rating of two hours, laminated or solid interior members, heavy plank or laminated wood floors and roofs.

Hip Roof - A roof consisting of four sloping planes that intersect to form a pyramid or elongated pyramid shape. A roof which slopes up toward the center from all sides, necessitating a hip rafter at each corner.

Humidity - The amount of water vapor in a given volume of air.

HVAC - Heating, ventilation, and air-conditioning system.

Hydronic Heating System - A system that circulates heated water through convectors to heat a building or given space.

I

I Beam - An obsolete term; an American Standard designation for a particular section of hot rolled steel which in cross section is shaped like a capital "I".

Ice Dam - An ice obstruction along the eaves of a roof caused by the refreezing of water emanating from melting snow on the roof surface above.

Incandescent fixture - An electric light fixture in which the lamp or bulb has a filament that gives off light when heated to incandescence by an electric current.

Independent Contractor - A person who, in performing services for another, is responsible only for the final result, and is not subject to control as to the methods used to achieve that result.

Infiltration - The exchange between conditioned room air and outdoor air through cracks and openings in the building enclosure.

Insulated Block - Hollow block masonry filled with insulation.

Insulation - Any material used to reduce the effects of heat, cold, or sound transmission and to reduce fire hazard. Any material used in the prevention of the transfer of electricity, heat, cold, moisture, and sound.

Insulative Panel - Flat sheet material made of insulative material to improve thermal resistance characteristics of assembly.

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

Irregular Stone - Stone cut to or quarried in different shapes and/or sizes.

J

Jack Rafter - A shortened rafter that joins a hip or valley to the top of a wall plate.

Jalousie Window - A window with stationary or adjustable blinds angled to permit air and provide shade, while at the same time preventing rain from entering.

Jamb - the vertical side of a door or window. The side piece or post of an opening; commonly applied to the door frame.

Joint - The point of connection between structural members.

Joint Clip - A fastener used vertically, sharp edges down, over the edges of two pieces, and then hammered down into them. In plywood sheathing, the clip fastens two abutting pieces of plywood.

Joist - One of a group of light, closely spaced beams used to support a floor deck or flat roof. Timbers supporting the floorboards.

Joist Hanger - A metal stirrup that supports the ends of joists so that they are flush with the girder.

Joule - In the international system of units, the amount of energy needed to raise one kilogram of water one degree Celsius.

Journeyman - An experienced reliable worker who has learned his trade and works from another person.

Junction Box - A metal box in which runs of cable meet and are protectively enclosed.

K

K Bracing - That form of bracing where a pair of braces located on one side of a column terminates at a single point within the clear column height.

Keyed Joint - A joint in which one structural member is keyed or notched into an adjoining member as in timber construction. In masonry construction, a finished joint of mortar which has been tooled concave.

Kick Plate - A metal strip or plate that runs along the bottom edge of a door to protect against the marring of the finished surface.

Kip - A unit of weight or force equal to 1,000 lbs.

Knee Brace - A corner brace, fastened at an angle from wall stud to rafter, stiffening a wood or steel frame to prevent angular movement.

L

Landscape - To improve a site by modification of the terrain, the addition of plant materials, and/or possible additions of hardscape.

Landscape Timber - Large treated lengths of lumber used to decorate and act as soil erosion barriers and retaining wall members.

Lavatory - A basin with drainage and running water primarily used for washing hands and face. A room with a toilet and wash basin.

Leg - A tile wall running alongside a bathtub or abutment. This term is sometimes used to describe a narrow strip of tile floor.

Linoleum - A resilient floor covering, commonly in sheet form.

Lintel - The horizontal beam placed over an opening.

Load Bearing - Supporting a superimposed weight or force.

Local Access Streets - Most of the low speed controlled access roads within sectors of a city, between collector streets, serving built-up areas, parking and pedestrians unrestricted.

Lot Line - The boundary of a parcel of land.

Luminaire - A complete lighting unit consisting of a light source, switch, globe, reflector, housing, and wiring.

M

Mantle - The decorative outer top or shelf over the inside face of a fireplace. The main bulk of the Earth between the crust and core.

Masonry - Brickwork, block work, and stonework.

Metal Framing - The construction of a building or structure by using steel. Loosely used term to denote the construction of frame houses and partitions by using light gauge metal studs and members.

Millwork - Interior components such as trim work, cabinets, doors and windows, etc. but not including floors, siding, and ceilings. Often made of wood or plastic laminates and produced in a shop or factory.

Moisture Barrier - A membrane used to prevent the migration of liquid water through a floor or wall.

Moisture Movement - The movement of moisture through a porous medium; the effects of such movement on efflorescence and volume change in hardened cement paste, mortar, concrete or rock.

Mono Pitch Truss - A truss that would develop a shed type roof.

Mortar - A mixture of cement paste and fine aggregate; in fresh concrete, the material occupying the interstices among particles of coarse aggregate; in masonry construction, mortar may contain masonry cement, or may contain hydraulic cement with lime to afford greater plasticity and workability than are attainable with standard hydraulic cement mortar. A substance used to join masonry units consisting of cementitious materials, fine aggregate, and water.

Mosaic - Tile with small inlaid pieces of porcelain or natural clay materials to form decorative patterns. Small tile or bits of tile, stone, or glass used to form a surface design or an intricate pattern.

Multi-zone Air Handling System - A system providing conditioned air similar to a single-zone system. The temperature and flow of the air supplying each zone is controlled separately. A constant supply of air is supplied to he various zones.

N

Natural Stone - Any type of stone that is quarried and not manufactured.

Needle Beam - A steel or wood beam threaded through a hole in a bearing wall and used to support the wall and its superimposed loads.

Neighborhood - In community planning, a residential area in which residents are within walking distance of each other.

Neoprene Membrane - An impervious, oil resistant synthetic rubber, manufactured to be installed in layer form. Used for roofing and waterproofing.

Newel - The principal post of the foot of the staircase; also the central support of a winding flight of stairs.

Nonbearing - Not carrying a load.

Normal Loading - A design load that stresses a member or fastening to the full allowable stress tabulated. This loading may be applied for approximately ten years, either continuously or cumulatively, and 90 percent of this load may be applied for the remainder of the life of the member or fastener.

Nosing - The projection forward edge of a stair tread. The parts of a stair tread which projects over the riser, or any similar projection; a term applied to the rounded edge of a board.

O

Oak - A strong, hard, heavy wood.

Obscure Glass - Ground glass or frosted glass that transmits light but does not allow a view of objects on the other side.

Ogee Roof - An architectural roof design which is eastern influenced.

Open Run-Around - A method of heat recovery from exhaust air in which a fluid is inserted alternately in the supply and exhaust air stream. This system transfers both sensible and latent heat.

Oriented Strand Board - A building panel composed of long shreds of wood fiber oriented in specific directions and bonded together under pressure. Commonly called "strand board" or OSB.

Outlet Box - A box or container which houses an electrical outlet and its connections.

Overhang Beam - A beam that is supported by two or more supports and has one or both ends projecting beyond the support.

Owner-Builder - An owner of property who undertakes to construct improvements thereon but does not employ a general contractor.

P

Paint - A mixture of pigment, binder, and solvent as a suitable liquid to form a thin closely adherent coating when spread on a surface in a thin coat to decorate or adorn by applying lines and color.

Parquet Floor - A floor covering laid out in a geometric design composed of small pieces of wood.

Particle Board - A building panel composed of small particles of wood and resins bonded together under pressure. Flat sheet material producing durable and dimensionally stable product that is often used in dry conditions in place of plywood.

Partition - A permanent interior wall that serves to divide a building into rooms.

Pitch - The frequency of sound vibrations. Inclination or slope, as for roofs or stairs, or the height divided by the span.

Plasterboard - A board used in large sheets as a backing or as a substitute for plaster in walls and consisting of fiberboard, paper, or felt, bonded to a hardened gypsum core. Loose term for drywall or sheetrock.

Platform Frame - A wooden building frame composed of closely spaced members nominally 2 inches in thickness, in which the wall members do not run past the floor framing members. Typical wood stud wall framing in which the studs are one level in height and the floor framing above rests on the top plates of the wall below. The most common type of framing used in house construction.

Plenum - Air compartment connected to a duct or ducts.

Plumbing - The act or progress of installing in a building or structure the pipes, fixtures, or other apparatus for supplying potable water and removing liquid and waterborne wastes. The installed fixtures and piping of a building or structure.

Plywood - A wood panel consisting of a number of layers of wood veneer bonded and glued together under pressure. Flat sheet material built up of sheets of veneer called plies, united under pressure by bonding agent to create a panel with adhesive bond between plies as strong as or stronger than the wood alone.

Precast - A concrete component horizontal structural member that is cast and cured in other than its final position.

PVC Pipe - Polyvinyl chloride pipe used mainly for drain lines and particularly resistant to chemicals.

Q

Quarry Tile - A large clay floor tile, usually unglazed.

R

R-Value - The number of minutes required for 1 BTU to penetrate one square foot of a material for each degree of temperature difference between the two sides of the material. The resistance of a material to the passage of heat. The reciprocal of conductors.

Rafter - A framing member that runs up and down the slope of a pitched roof. The beams that slope from the ridge of a roof to the eaves and make up the main body of the roof's framework.

Railing - An open fence or guard for safety, made of rails and posts. A banding in cabinetwork. On plywood, the solid wood band around one or more edges.

Reducer - A pipefitting that connects pipes of different sizes. A tile trim unit used to reduce the radius of a bull nose or a cove to another radius or to a square.

Reinforced Concrete - Concrete containing adequate reinforcement and designed on the assumption that concrete and steel act together in resisting forces. Concrete work into which steel bars have been embedded to impart tensile strength to the member.

Relative Humidity - The ratio of the quantity water vapor actually present to amount present in a saturated atmosphere at a given temperature; expressed as a percentage. The ratio of the actual vapor pressure of the air-vapor pressure to the pressure of saturated water vapor at the same dry-bulb temperatures time 100.

Riser - A single vertical increment of a stair; the vertical face between two treads in a stair; a vertical run of plumbing, wiring, or ductwork. The vertical board between two treads of a flight of stairs, extending from the back edge of one tread to the leading edge of the tread above it.

Run - Horizontal dimension in a stair. The length of the horizontal projection of a piece such as a rafter when in position.

S

Salamander - A portable source of heat customarily kerosene or oil burning, used to temporarily heat an enclosure. Commonly used around newly placed concrete to prevent freezing.

Sandblast - A system of cutting or abrading a surface such as concrete by a stream of sand ejected from a nozzle at a high speed. Compressed air is used to propel a stream of wet or dry sand onto the surface. Often used for cleanup of horizontal construction joints or for the exposure of aggregate in architectural concrete. A method of scarifying the surface of concrete or masonry to provide a bondable surface. Also used to clean metal before painting.

Sealant - An elastomeric material that is used to fill and seal cracks and joints. At expansion joints, this material prevents the passage of moisture and allows horizontal and lateral movement.

Septic Tank - A private sewage system holding tank, installed together with a leaching field, that collects sewage and allows the solid waste to settle to the bottom of an area while the liquid particles of the sewage drain into the leaching field area.

Sheathing - The rough covering applied to the outside of the roof, wall, or floor framing of a structure. In clay tile or wood shingle/shake roofs, roofing boards generally installed as narrow boards laid with a space between them, according to the length of a shingle or tile exposed to weather.

Sheetrock - Plasterboard sheets, an interior facing panel consisting of a gypsum core sandwiched between paper faces, also called gypsum board or plasterboard. Different types are available for standard, fire-resistant, water-resistant, and other applications.

Shingle - A small thin piece of building material often with one end thicker than the other for lying in overlapping rows as a covering for the roof or sides of a building or structure.

Sick Building Syndrome - Term commonly used to describe situations in which building occupants experience acute health and\or comfort effects that appears to be linked to time spent in a particular building, but where no specific illness or cause can be identified. The complaints may be localized in a particular room or zone, or may be spread throughout the entire building or structure.

Soffit - The underside part of a member of a structure, such as a beam, stairway, roof, or arch. The undersurface of a horizontal element of a building, especially the undersides of a stair or roof overhang.

Soldier - A brick laid on its end, with its narrow face toward the outside of the wall.
Specifications - A description of systems, materials, and facilities to be employed in building a structure, and incorporated into a contract for construction. A written document for the project indicating quality and supplementing the working drawings. The written or printed directions regarding the details of a building or other construction.

Standpipe - A pipe that extends the full height of a building, with hose connections, used to provide water exclusively for the fighting of fires. A dry standpipe does not have water in it until a valve is activated. A wet standpipe is directly connected to a water supply and usually located in a stairway.

Strength Design - A design theory used for most reinforced concrete designs. A design in which members are assigned to fail. Safety is not provided by limiting stresses, but by using a factored load that is greater than the actual load.

Stringer - The sloping wood or steel member supporting the treads of a stair. The long horizontal timber in a structure supporting the floor.

Sub-Flooring - Certain material, like plywood, that is installed on the floor joists of a building or structure, onto which the walls and finished flooring is attached.

Surface Waters - Rainwater collected and running on the surface of the land rather than being confined to drains and water courses.

Surveying - A branch of applied mathematics, including geometry and trigonometry, that aids in determining and delineating the form, extent, and position of the land.

T

Take-Off Man - Someone who can read blueprints and is familiar with the specifications. This person makes notes of special details concerning the project after gathering the necessary information and then estimates the quantities of labor, materials, and equipment special items needed to complete the job. Also may be called a quantity surveyor.

Tensile strength - The pulling force necessary to break a given specimen divided by the cross sectional area. Units given in lbs/in. It measures the resistance of a material to stretching without rupture. Normally is not used with reference to elastic materials that recover after elongation. The ability of a structural material to withstand tensile forces.

Tension Ring - A structural element forming a closed curve in plan, which is in tension because of the action of the rest of the structure. A concrete or masonry dome commonly has a tension ring.

Thomas Jefferson Ideas - The advocacy of grid pattern planning where frequent public squares are left open between building blocks.

Threshold - The wood or metal beveled floor piece at door openings that commonly separates non-continuous floor types.

Tile - A ceramic surfacing unit, usually relatively thin in relation to facial area, made from clay or a mixture of clay and other ceramic materials, called the body of the tile, having either a glazed or unglazed face and fired above red heat in the course of manufacture to a temperature sufficiently high to produce specific physical properties and characteristics. A fired clay product that is thin is cross section compared to a brick; either a thin/flat element, a thin/curved element, a hollow element with thin walls, or a pipe-like shape.

Timber - Lumber with a cross-section over 4 by 6 inches, such as posts, sills, and girders.

Topography - The form of the terrain. The description of the surface features in graphic terms is depicted by contours.

Transom - A transverse piece in a structure, a lintel. A horizontal crossbar in a window, over a door, or between a door and a window or fanlight above it. A window above a door or other window built on and commonly hinged to a transom

Truss - A triangular arrangement of structural members that reduces nonaxial forces on the truss to a set of axial forces in the members. Structural framework of triangular units for supporting loads over long spans.

U

U Bolt - A U-shaped, bent iron bar that has bolts and threads at both ends.

U Stirrup - An open-top, U-shaped loop of steel bar used as reinforcement against diagonal tension in a beam.

Ultimate Load - The absolute maximum magnitude of load which a structure can sustain, limited only by ultimate failure.

Undercourse - A course of shingles laid beneath an exposed course shingles at the lower edge of a wall or roof, in order to provide a waterproof layer behind the joints in the exposed course.

Underlayment - A layer of hardboard, particleboard, plywood, mastic with latex binders, mastic with asphalt binders, mastic with polyvinyl-acetate binders, etc., placed to cover subfloor irregularities, to absorb the movement of wood subfloors and to provide a smooth surface for the finish flooring material.

Union - A type of pipe fitting used to join two pipes in a line without turning either pipe.

Utility - A service provided by a public utility (power, light, or water)

Utility excavation - The act or process of either digging up existing cable buried in the ground, or trenching to lay new cable.

V

Valley - A trough or internal angle formed by the intersection of two roof slopes. The internal angle formed by two slopes of a roof.

Valve - Numerous mechanical devices by which the flow of liquid, gas, or loose material, in bulk may be stopped, started, or regulated by a moveable part that opens, shuts, or partially obstructs one or more passageways.

Vapor Barrier - Waterproof membrane placed under concrete floor slabs that are on grade.

Vapor Retarder - A layer of material intended to obstruct the passage of water vapor through a building assembly. Also called, less accurately, vapor barrier. Sealing material placed between building components or materials to arrest movement of moisture within building enclosure assembly.

Varnish - A colorless, clear, resinous product dissolved in oil, alcohol, or a number of volatile liquids, applied to wood to provide a hard, glossy, protective, film.

Veneer - A thin layer, sheet or facing.

Vent - A vertical pipe connected to a waste or soil distribution system that prevents a vacuum that might suck the water out of the trap. A vertical pipe that provides a passageway for the expulsion of vent gases from gas burning equipment to the outside air.

Vestibule - An entrance to a house that is usually enclosed.

Vitreous - That degree of vitrification evidenced by low water absorption. The term vitreous generally signifies less than 0.5% absorption, except for floor and wall tile and low-voltage electrical porcelain that are considered vitreous up to 3.0% water absorption.

Voltage - Electricity is caused by creating a higher electric charge at one point in a conductor than at another. This potential difference is called voltage.

W

Wainscoting - A wall facing, usually of wood, cut stone, or ceramic tile, that is carried only part way up a wall. Matched boarding or panel work that covers the lower portion of a wall.

Washer - A flat thin ring or a perforated plate used in joints or assemblies to ensure tightness or relieve friction.

Water Table - The level at which the pressure of the water in the soil is equal to atmospheric pressure; effectively to the level which ground water will fill an excavation. The finish at the bottom of the house, which carries water away from the foundation. A projection on the bottom of an exterior wall made to prevent rain or water from seeping through to the wall below.

Waterproof Membrane - A membrane that can be made of built-up roofing or an elastometric sheet, to provide positive waterproofing for a floor wall.

Weld - A joint between two pieces of metal formed by fusing the pieces together, usually with the aid of additional metal melted from a rod or electrode. Join two pieces of metal together by heating until fusion of material with or without filler metal.

Well - A pit or hole sunk into the earth to reach a supply of water. An open space extending vertically through floors of a structure.

Well Point System - A series of vertical pipes in the ground connected to a header and pump to drain marshy areas or to control ground seepage.

Wind Brace - A diagonal structural member whose function is to stabilize a frame against lateral forces.

Winder - A stair tread that is wider at one end than at the other.

Wobble Friction - In prestressed concrete, friction caused by unintended deviation of prestressing sheath or duct from its specified profile.

Wood Blocking - Small pieces of wood used to secure, join, or reinforce members, or to fill spaces between members.

Wood Decking - Plywood, lumbers, or glued laminated member placed over roof or floor structural members for structural rigidity of building frame and to provide a surface for traffic or substrate for roofing or flooring system.