- A -
ABS A type of black plastic pipe commonly used for waste water lines.
Aggregate Crushed rock or stone.
Air chamber A vertical, air filled pipe that prevents water hammer by absorbing pressure when water is shut off at a faucet or valve.
Air-conditioner condenser The outside fan unit of the air conditioning system. The condenser discharges heat to the building exterior.
Alligatoring Coarse checking pattern on the surface of a material. Typically caused by ageing, exposure to sun and/or loss of volatiles.
Ampacity Refers to the how much current a wire can safely carry. For example, a 12-gauge electrical copper wire can safely carry up to 20 amps.
Asphalt A bituminous material employed in roofing and road paving materials because of its waterproofing ability.
- B -
Backfill The replacement of excavated earth into a trench or pit.
Backflow A reverse flow of water or other liquids into the water supply pipes, caused by negative pressure in the pipes
Ballast A transformer that steps up the voltage in a florescent lamp.
Balusters Vertical members in a railing used between a top rail and bottom rail or the stair treads. Sometimes referred to as pickets or spindles.
Base sheet Bottom layer of built-up roofing.
Batt A section of fiberglass or rock-wool insulation.
Bay window Any window space projecting outward from the walls of a building, either square or polygonal in plan.
Beam A structural member transversely supporting a load. A structural member carrying building loads (weight) from one support to another. Sometimes called a girder.
Bearing wall A wall that supports any vertical load in addition to its own weight.
Bird's-mouth cut A cutout in a rafter where it crosses the top plate of the wall providing a bearing surface for nailing. Also called a heel cut.
Bitumen Term commonly applied to various mixtures of naturally occurring solid or liquid hydrocarbons, excluding coal. These substances are described as bituminous. Asphalt is a bitumen. See Asphalt.
Blocking Small wood pieces to brace framing members or to provide a nailing base for gypsum board or paneling.
Board and batten A method of siding in which the joints between vertically placed boards or plywood are covered by narrow strips of wood.
Bottom chord The lower or bottom horizontal member of a truss.
Brick tie Metal strips or wires that are inserted into the mortar joints of the brick veneer. Ties hold the veneer wall to the backer wall behind it.
Brick veneer A vertical facing of brick used to clad a building. Brick veneer is not a load-bearing component.
Btu's - British Thermal Unit. The amount of heat required to raise the temperature of one pound of water one degree. A measure of heat performance.
Building paper A general term for papers, felts and similar sheet materials used in buildings without reference to their properties or uses. Generally comes in long rolls.
Built-up roof A roofing composed of three to five layers of asphalt felt laminated with coal tar, pitch or asphalt. The top is finished with crushed slag or gravel. Generally used on flat or low-pitched roofs.
Butt joint The junction where the ends of building materials meet. To place materials end-to-end or end-to-edge without overlapping.
- C -
Cant strip A triangular shaped piece of lumber used at the junction of a flat deck and a wall to prevent cracking of the roofing which is applied over it.
Cantilever Any part of a structure that projects beyond its main support and is balanced on it.
Cap flashing The flashing covering over a horizontal surface to prevent water from migrating behind the base flashing.
Cap sheet The top layer in modified bitumen roofing.
Casement window A window with hinges on one of the vertical sides and swings open like a door.
Ceiling joist One of a series of parallel framing members used to support ceiling loads and supported in turn by larger beams, girders or bearing walls. Can also be roof joists.
Cement The grey powder that is the "glue" in concrete. Portland cement. Also, any adhesive.
Certificate of Occupancy Certificate is issued by the local municipality and is required before anyone can occupy and live within the building. It is issued only after the local municipality has made all inspections and all monies and fees have been paid.
cfm (cubic feet per minute) A rating that expresses the amount of air a blower or fan can move. The volume of air (measured in cubic feet) that can pass through an opening in one minute.
Chase A framed enclosed space around a flue pipe or a channel in a wall, or through a ceiling for something to lie in or pass through.
Checking Cracks that appear with age in many large timber members. The cracks run parallel to the grain of the wood. At first superficial, but in time may penetrate entirely through the member and compromise its integrity.
Cleanout An opening providing access to a drain line. Closed with a threaded plug.
Closed-cut valley A method of valley treatment in which shingles from one side of the valley extend across the valley, while shingles from the other side are trimmed 2 inches from the valley centerline. The valley flashing is not exposed.
Collar tie Nominal one- or two-inch-thick members connecting opposite roof rafters. They serve to stiffen the roof structure.
Column A vertical structural compression member that supports loads acting in the direction of its longitudinal axis.
Combustion air and ventilation air The ductwork installed to bring fresh, outside air to the furnace or boiler room. Normally two separate supplies of air are brought in: one high for ventilation and one low for combustion.
Compressor A mechanical device that pressurizes a gas in order to turn it into a liquid, thereby allowing heat to be removed or added. A compressor is the main component of conventional heat pumps and air conditioners. In an air conditioning system, the compressor normally sits outside and has a large fan (to remove heat).
Concrete board or cement board A panel made out of concrete and fiberglass, usually used as a tile backing material.
Condensate drain line The pipe that runs from the air conditioning cooling coil to the exterior or internal building drain, to drain away condensation.
Condensation The change of water from vapor to liquid when warm, moisture-laden air comes in contact with a cold surface.
Condensing unit The outdoor component of a cooling system. It includes a compressor and condensing coil designed to give off heat.
Conduit, electrical A pipe, usually metal, in which wire is installed. The pipe serves to protect the wire.
Control joint Tooled, straight grooves made on concrete floors or structures to "control" where the concrete should crack (as a result of shrinkage).
Cooling load The amount of cooling required to keep a building at a specified temperature during the summer, usually 25° C, based on a design outside temperature.
Corbel To build out one or more courses of brick or stone from the face of a wall. This may be decorative, or serve to support a structural component.
Counter-flashing A metal flashing usually used to cover another flashing and prevent moisture entry.
Course A row of shingles or roll roofing running the length of the roof. Parallel layers of building materials such as bricks, or siding laid up horizontally.
CPVC See PVC.
Crawlspace A shallow space below a building, normally enclosed by the foundation walls.
Cricket A saddle-shaped, peaked construction connecting a sloping roof plane with a wall or chimney. Designed to
encourage water drainage away from the chimney or wall joint.
Culvert Round, corrugated drain pipe (normally 15 or 18 inches in diameter) installed beneath a driveway and parallel to and near the street.
Cupping A type of warping that causes boards or shingles to curl up at their edges. Typically caused by uneven drying or loss of volatiles.
Curb The short elevation of a supporting element above the deck of a roof. Normally a box (on the roof) on which a skylight or piece of mechanical equipment is attached.
Curtain wall An exterior building wall that is supported entirely by the building structure, rather than being self-supporting or load-bearing.
- D -
Damper A metal "door" placed within the ductwork, typically. Used to control flow of air, etc., in the ductwork.
Damp-proofing The black, tar-like material applied to the exterior of a foundation wall. Used to minimize moisture penetration into the wall.
Deck The surface, installed over the supporting framing members, to which the roofing is applied.
Dedicated circuit An electrical circuit that serves only one appliance or a series of electric heaters or smoke detectors.
Dew point Temperature at which a vapor begins to deposit as a liquid. Applies especially to water in the atmosphere.
Disconnect A large electrical on-off switch.
Diverter valve A device that changes the direction of water flow from one faucet to another.
Dormer A box-like projection from the sloping plane of a roof that frames a window.
Double-hung window A window with two vertically sliding sashes, both of which can move up and down.
Downspout A pipe for draining water from roof gutters. Also called a leader.
Drain tile A perforated, corrugated plastic pipe laid at the bottom of the foundation wall and used to drain excess
water away from the foundation. It prevents ground water from seeping through the foundation wall. Sometimes called perimeter drain.
Drip A groove in the underside of a sill or drip cap to cause water to drop off on the outer edge instead of drawing back and running down the face of the building.
Ducts Usually round or rectangular metal pipes installed for distributing warm or cold air from the heating and air-conditioning equipment.
- E -
Eaves protection Additional layer of roofing material applied at the eaves to help prevent damage from water backup (typically caused by ice damming).
EIFS Exterior Insulation Finish System. An exterior cladding system that employs a relatively thin acrylic stucco coating over insulation panels. (Pronounced "ee-fus")
Efflorescence - a powdery substance or incrustation resulting from water seepage through brick, concrete or wood.
Elbow A plumbing or electrical fitting that lets you change directions in runs of pipe or conduit.
Evaporator coil The part of a cooling system that absorbs heat from air passing through it. The evaporator coil is found within the ductwork.
Expansion joint A joint that allows for building material expansion and contraction caused by temperature changes.
Exposed aggregate finish A method of finishing concrete which washes the cement/sand mixture off the top layer of the aggregate usually gravel. Often used with pre-cast concrete exterior wall finishes.
Exposure The portion of the roofing or wall cladding material exposed to the weather after installation.
- F -
Fascia a vertical member attached to the ends of the roof structure and often the backing of the gutter.
Felt Fibrous material saturated with asphalt and used as an under-layment or part of a built-up roofing system.
Finger joint A manufacturing process of interlocking two shorter pieces of wood end to end to create a longer piece of dimensional lumber or molding. Often used in jambs and casings and are normally painted (instead of stained).
Fire stop A solid, tight closure of a concealed space, placed to prevent the spread of fire and smoke through such a space. Includes stuffing wire and pipe holes in the fire separations.
Flashing (1) Sheet metal or flexible membrane pieces fitted to the joint of any roof intersection, penetration or projection (chimneys, copings, dormers, valleys, vent pipes, etc.) to prevent water leakage. (2) The building component used to connect portions of a roof, deck, or siding material to another surface such as a chimney, wall, or vent pipe. Often made out of various metals, rubber or tar and is mostly intended to prevent water entry.
Flatwork Common word for concrete floors, driveways, patios and sidewalks.
Flue The space or passage in a chimney through which smoke, gas, or fumes ascend.
Fluorescent lighting A fluorescent lamp is a gas-filled glass tube with a phosphor coating on the inside. Gas inside the tube is ionized by electricity which causes the phosphor coating to glow. Normally with two pins that extend from each end.
Footing A widened, below-ground base of a foundation wall or a poured concrete, below-ground, base used to support foundations or piers.
Forced air heating a common form of heating with natural gas, propane, oil or electricity as a fuel. Air is heated through a heat exchanger and distributed through a set of metal ducts.
Form Temporary structure erected to contain concrete during placing and initial hardening.
Foundation The supporting portion of a structure below the first floor construction, or below grade, including the footings.
Framing The structural wood, steel or concrete elements of the building.
Framing, balloon A system of framing a building in which all vertical structural elements of the bearing walls consist of single pieces extending from the top of the foundation sill plate to the roof plate and to which all floor joists are fastened.
Frost line The depth of frost penetration in soil and/or the depth at which the earth will freeze and swell. This depth varies in different parts of the country.
Furring Strips of wood or metal applied to a wall or other surface to even it and normally to serve as a fastening base for finish material.
- G -
Gable A sidewall, typically triangular, that is formed by two sloping roof planes.
Gable roof A type of roof with sloping planes of the same pitch on each side of the ridge. Has a gable at each end.
Gasket A device used to seal joints against leaks.
GFI, GFCI or Ground Fault Current Interrupter A electrical device used to prevent injury in locations where one might be in contact with a grounded surface and an electrical appliance. Most GFCI are located in a receptacle or circuit breaker and can be identified by the presence of a "test" and a "reset" button.
Glued laminated beam (glue-lam) A structural beam composed of wood laminations. The laminations are pressure-bonded with adhesives.
Granules Crushed rock coated with ceramic material, applied to the exposed surface of asphalt roofing products to add color and reduce ultraviolet degradation. Copper compounds added to these help make them algae resistant.
Groundwater Water from a subsurface water source.
Grout Mortar made of such consistency (by adding water) that it will flow into the joints and cavities of the masonry work and fill them solid.
Gusset A flat metal, wood, plywood or similar type member used to provide a connection at the intersection of wood members. Most commonly used at joints of wood trusses. They are fastened by nails, screws, bolts, or adhesives.
Gutter The trough that channels water from the eaves to the downspouts.
- H -
H-beam A steel beam with a cross section resembling the letter H.
H-clip Small metal clips formed like an H that fits at the joints of two plywood (or wafer board) sheets to stiffen the joint. Normally used on the roof sheeting.
Header A beam placed perpendicular to joists and to which joists are attached in framing for around an opening.
Hearth The fireproof area directly in front of a fireplace. The inner or outer floor of a fireplace, usually made of brick, tile, or stone.