Glossary of Construction Terminology



tab - The exposed portion of strip shingles defined by cutouts.

tail beam - A relatively short beam or joist supported in a wall on one end and by a header at the other.

taping - The process of covering drywall joints with paper tape and joint compound.

T-bar - Ribbed "T" shaped bars with a flat metal plate at the bottom that are driven into the earth. Normally used chain link fence poles, and to mark locations of a water meter pit.

tear off - In roofing, a term used to describe the complete removal of the built up roof membrane and insulation down to and exposing the roof deck.

tee - A "T" shaped plumbing fitting.

tempered - Strengthened. Tempered glass will not shatter nor create shards, but will "pelletize" like an automobile window. Required in tub and shower enclosures and locations, entry door glass and sidelight glass, and in windows when the window sill is less than 16" to the floor.

termites - Wood eating insects that superficially resemble ants in size and general appearance, and live in colonies.

termite shield - A shield, usually of galvanize metal, placed in or on a foundtaion wall or around pipes to prevent the passage of termites.

terra cotta - A ceramic material molded in masonry units.

thermal movement - The measured amount of dimensional change that a material exhibits as it is warmed or cooled.

thermal shock - The stress built up by sudden and appreciable changes in termperature.

Thermostat - A device which relegates the temperature of a room or building by switching heating or cooling equipment on or off.

three-dimensional shingles - Laminated shingles. Shingles that have added dimensionality because of extra layers or tabs, giving a shake-like appearance. May also be called "architectural shingles".

three-phase - A wiring system consisting of 4 wires and used in industrial and commercial applications. This system is suitable for installations requiring large motors. It consists of three hot wires and one ground wire. The voltage in each hot wire is out of phase with the others by 1/3 of a cycle, as if produced by three different generators.

threshold - The bottom metal or wood plate of an exterior door frame. Generally they are adjustable to keep a tight fit with the door slab.

tie-in - In roofing, a term used to describe the joining of a new roof with the old.

tilt-up wall - Cast concrete units which are preformed which, when cured, are tilted to their vertical position and secured by mechanical fasteners to prior erected structural steel. May be pre-cast.

Time & Materials Contract - A construction contract which specifies a price for different elements of the work such as cost per hour of labor, overhead, profit, etc. A contract which may not have a maximum price, or may state a 'price not to exceed'.

tinner - Another name for the heating contractor.

tip up - The downspout extension that directs water (from the home's gutter system) away from the home. They typically swing up when mowing the lawn, etc.

Title 24 - A federal set of laws that mandates the construction industry to conserve energy.

toe-nailing - To drive a nail in at a slant. Method used to secure floor joists to the plate.

tongue & groove - A type of flooring where the tongue of one board is joined to the groove of another board.

top chord - The upper or top member of a truss.

top plate - Top horizontal member of a frame wall supporting ceiling joists, rafters, or other members.

trap - A plumbing fitting that holds water to prevent air, gas, and vermin from backing up into a fixture.

tread - The walking surface board in a stairway on which the foot is placed.

treated lumber - A wood product which has been impregnated with chemical pesticides such as Chromated Copper Arsenate to reduce damage from wood rot or insects. Often used for the portions of a structure which are likely to be in contact with soil and water. Wood may also be treated with a fire retardant.

trim (plumbing, heating, electrical) - The work that the "mechanical" contractors perform to finish their respective aspects of work, and when the home is nearing completion and occupancy.

trim-interior - The finish materials in a building, such as moldings applied around openings (window trim, door trim) or at the floor and ceiling of rooms (baseboard, cornice, and other moldings).

trimmer - A beam or joist to which a header is nailed in framing for a chimney, stairway, or other opening.

truss - A frame or jointed structure designed to act as a beam of long span, while each member is usually subjected to longitudinal stress only, either tension or compression.

tuck pointing - The re-grouting of defective mortar joints in a masonry or brick wall.

turpentine - A volatile oil used as a thinner in paints and as a solvent in varnishes. Chemically, it is a mixture of terpenes.


UL (Underwriters' Laboratories) An independent testing agency that checks electrical devices and other components for possible safety hazards.

undercoat - A coating applied prior to the finishing or top coats of a paint job. It may be the first of two or the second of three coats. Sometimes called the Prime coat.

underground plumbing - The plumbing drain and waste lines that are installed beneath a basement floor.

underlayment - A 1/4" material placed over the subfloor plywood sheeting and under finish covering such as vinyl flooring, to provide a smooth, even surface. Also a secondary roofing layer that is waterproof or water-resistant, installed on the roof deck and beneath shingles or other roof-finishing layer.

union - A plumbing fitting that joins pipes end-to-end so they can dismantled.

upright - Vertical members supporting the sides of a trench.

utility easement - The area of earth that has electric, gas, or telephone lines. These areas may be owned by the homeowner, but the utility company has the legal right to enter the area as necessary to repair or service the lines.


valley - The "V" shaped area of a roof where two sloping roofs meet. Water drains off the roof at the valleys.

valley flashing - Sheet metal that lays in the "V" area of a roof valley.

valuation - An inspection carried out for the benefit of the mortgage lender to ascertain if a property is a good security for a loan.

valuation fee - The fee paid by the prospective borrower for the lender's inspection of the property. Normally paid upon loan application.

valve - A device to stop, start or regulate the flow of liquid or gas through or from piping.

vapor barrier - A building product installed on exterior walls and ceilings under the drywall and on the warm side of the insulation. It is used to retard the movement of water vapor into walls and prevent condensation within them. Normally, polyethylene plastic sheeting is used.

vent - A pipe or duct which allows the flow of air and gasses to the outside. Also, another word for the moving glass part of a window sash, i.e. window vent.

vent system - A system to provide a flow of air to or from a drainage system or to provide circulation of air within such systems to protect traps seals from siphonage and back pressure.

vermiculite - A mineral used as bulk insulation and also as aggregate in insulating and acoustical plaster and in insulating concrete floors.

viscosity - The internal frictional resistance offered by a fluid to change of shape or to the relative motion or flow of its parts.

visqueen - A 4 mil or 6 mil plastic sheeting.

void - Cardboard rectangular boxes that are installed between the earth (between caissons) and the concrete foundation wall. Used when expansive soils are present.

voltage - A measure if electrical potential. Most homes are wired with 110 and 220 volts lines. The 110V power is used for lighting and most of the other circuits. The 220V power is usually used for the kitchen range, hot water and dryer.

voltmeter - Measures the voltage flowing through a circuit. The circuit must be closed to allow the voltage to flow.