AIR BARRIER:

material or surface designed to prevent passage of air, but not water vapor.

AIR GAP: a separation between any pipe or faucet conveying water and the flood-level rim of any plumbing receptacle.

AMPACITY: ampere-carrying capacity of a wire.

AMPERE: unit of electrical current. Often abbreviated amp.

ANTI-SIPHON VALVE: valve on a lawn sprinkler that prevents the sprinkler water from backflowing into the main water supply.

ASBESTOS: a fire and heat-resistant material used in construction until the early 1970s, when it was discovered to pose health hazards.

ASH DUMP: opening in the floor of a fireplace for ash disposal.

ASPHALT PLASTIC CEMENT: asphalt used to seal roofing materials together.

ATTIC: the space under the roof of a structure but above the top floor.

BACK-FLOW PREVENTER VALVE: see anti-siphon valve above.

BALLOON FRAME: wood frame in which studs are continuous from the sill plate to the top plate of the top floor.

BALUSTER: vertical member under a stair, deck, or porch railing.

BASEBOARD: Any board or molding covering an interior wall where it meets the floor.

BATT: An oblong blanket of fiberglass insulation.

BATTEN: thin wood molding used to cover a joint (usually used with siding).

BAY WINDOW: window that projects outward from the wall.

BEARING WALL: wall that supports a load from above, such as a vertical load of a roof system.

BlTUMIN: substance containing oil or coal-based compounds; (asphalt based roofing material).

BRANCH CIRCUIT: one of several circuits in a building, originating at   the service entrance panel and protected by a separate circuit breaker or fuse.

BRICK VENEER: brick facing over wood or masonry frame.

BRIDGING: bracing between floor joists to prevent twisting of joists.

BRITISH THERMAL UNIT (BTU): amount of heat required to raise the temperature of 1 pound of water by 1 degree.

BUILDING PAPER: a waterproof  heavy paper used in construction of  a roof or wall.

BUILT-UP ROOF: roofing consisting of many alternating layers of asphalt and felt.

BUSS BAR: rectangular metal bar (usually copper) for carrying large electrical current.

BUTT JOINT: joint in which two members meet without overlap or miter.

CAPILLARY: movement of water  through small gaps due to adhesion and surface tension.

CASEMENT WINDOW: window hinged on the side and opening outward.

CASING: inside or outside molding.

CELLULOSE INSULATION: loose-fill insulation consisting of shredded and treated newspaper.

CHECK: cracks in the surface of wood resulting from drying and shrinking of the surface faster then the interior.

CLEANOUT PLUG: a threaded fitting in a pipe or fixture that provides access for cleaning or drainage.

CIRCUIT: two or more wires carrying electricity to lights, receptacles, switches and appliances.

CIRCUIT BREAKER: electromechanical device that opens when the circuit exceeds its electrical capacity.

CLAPBOARD: board used for overlapping as horizontal siding.

CLOSED VALLEY: roof valley where the shingles extend in an unbroken line across the valley intersection.

COLLAR TIE BEAM: a horizontal beam fastened above the upper ends of rafters to stabilize them.

CONDUCTOR: wire intended to carry electrical current.

CONDUIT: metal or plastic pipe that surrounds electrical wires and protects them from physical damage.

CONVECTION: heat transfer through either the natural or forced movement of air.

COUNTERSINK: to sink a nail or screw below the surface.

CRAWLSPACE: a space between the ground and the first floor of a house that allows access for repair of utilities that run under the house.

CRICKET: small roof for diverting  water away from the back side of a chimney.

CRIPPLE WALL: a short wall built upon the foundation of a house that produces a high crawlspace.

DAMPER: an adjustable plate in the flue of a fireplace or furnace that is used to control the draft from the flames.

DAMP-PROOFING: water-proofing a masonry surface to retard capillary action and water leaks.

DEAD LOAD: load imposed on a structure by the weight of the building materials only.

DECAY: deterioration of wood from attack by fungi or insects.

DEW POINT: air temperature at which water vapor begins to condense as either water or ice (frost).

DIELECTRIC UNION: type of connector that insulates two different types of metal pipe to prevent electrolysis.

DIMENSION LUMBER: framing lumber 2 to 5 inches in thickness and up to 12 inches in nominal width.

DIVERSION VALVE: valve in a septic tank system that allows the user to alternate leach lines.

DORMER: vertical window projecting from a roof; gabled dormers have peaked roofs, shed dormers have shed roofs.

DOUBLE GLAZING: insulated window pane formed by two thicknesses of glass with a sealed air space between them.

DOUBLE LUGGING: running two or more electrical circuits off a single lug (terminal or connector).

DOWNSPOUT: pipes leading from the gutters of a roof to the ground and away from the building.

DRAINAGE: gradual flowing of liquids off a surface. Any system to remove liquid waste or rainwater by channeling its flow to a designated area.

DRIP EDGE: material designed to force water to drip away from roof  rakes and eaves.

DUCTS: any conduit for hot air, gas, water, electrical wiring, etc.

EAVES: the lower part of a roof that projects beyond an exterior wall.

EGRESS WINDOW: window whose clear dimensions are large enough that it can serve as a fire exit.

ELEVATION: view of a vertical face of a building.

FASCIA: vertical flat board at the roof eaves, that the gutters are attached to.

FIREBRICK: special clay brick that can be exposed to extremely high temperature change without damage; used in furnaces, fireplaces and similar high temperature areas.

FIRE-STOP: framing member designed to block the spread of fire within a framing cavity.

FLASHING: sheet metal or similar materials used at different points in a structure to prevent water seepage, such as around vent pipes or   chimneys.

FLOOR FURNACE: a ductless  furnace placed directly below a floor that transmits heat only through a grille in the floor.

FLOOR JOIST: a framing piece that rests on the outer foundation walls and interior beams or girders, and supports the flooring above.

FLUE: the opening or passageway in a chimney through which smoke, gases, etc., pass from a building. Any opening or passageway for the elimination of gases or fumes.

FOOTING: foot like projection at the base of a foundation wall, column, pier, etc., used to secure, support, and help eliminate settling or shifting of the wall.

FORCED-AIR FURNACE: furnace that has a fan or blower which forces warm air through the ducts.

FOUNDATION: the part of a building, usually below ground level, that supports the superstructure above it.

FRAMING: wood structure of a building that provides its strength and shape; includes exterior and interior walls, floor, roof, and ceilings.

FRIEZE: in wood construction, the horizontal board between the top of the siding and the soffit.

FROST HEAVE: expansion of the earth due to freezing of interstitial water.

FROST LINE: maximum depth of  freezing in the soil.

FUSE: a short plug in an electric  panel box that interrupts an electrical    circuit when it becomes overloaded.

GIRDER: a large or principal beam used to support concentrated loads or weight at particular points along   its length.

GLAZING: glass or other transparent material used for windows.

GRADE: level of the ground.

GROUNDED WIRE: wire in a circuit that is connected to the ground and serves to return current from the hot   wire back to the ground. Identified by a white insulation jacket.

GROUND FAULT INTERRUPTER: (GFI or GFCI) circuit breaker that trips on leakage of current.

GROUNDING WIRE: bare or green wire in a circuit that connects metal components, such as appliance cabinets, to the ground.

GROUT: very thin mortar applied to masonry joints.

HEADER: beam over a door or window for supporting the load from above.

HEARTH: The stone or brick floor of a fireplace.

HYDRONIC: method of distributing heat by hot water.

I-BEAM: steel whose cross section resembles the letter I.

ICE DAM: ridge of ice at roof eaves or gutters causing snow and ice blockage, and preventing from properly draining.

INFILTRATION: Incursion of outdoor air through cracks, holes and joints.

INSULATING GLASS: factory-sealed double or triple glazing.

JAMB: top and sides of a door or window.

JOINT COMPOUND: material used to finish joints in gypsum drywall. Known as mud.

JOIST: see floor joist.

JUNCTION BOX (J-box): a device in which wires are spliced to bring various electrical circuits together.

KNOB-AND-TUBE WIRING: oldest type of electrical wiring; the knobs serve as insulators, and the ceramic tubes isolate the wiring from neighboring wood.

LATH: perforated base for application of plaster; formerly wood, now usually metal.

LATTICE: framework of crossed strips of wood, plastic, or metal.

LEACH LINE: a gravel-filled subsurface trench extending from a   septic tank; liquid wastes are absorbed into the leach line's soil

LOAD-BEARING WALL: a wall capable of supporting weight.

LINTEL: solid member above a door or window that carries the load above.

LIVE LOAD: temporary load imposed on a building by occupancy and the environment.

MASONRY:  construction consisting of stone, brick, or concrete block.

MEMBRANE ROOF: roofing consisting of a single waterproof sheet.

MITER: to cut at an angle other than 90 degrees.

MOISTURE BARRIER: treated paper or metal that retards or bars water vapor, used to keep moisture from passing into walls or floors.

MORTAR: mixture of cement, sand, and water.

NEUTRAL WIRE: grounded wire.

NON-BEARING WALL: wall or partition that does not carry a load from above.

NOSING: projection of a stair tread beyond the riser.

ON CENTER (OC): framing measurement from the center of one member to the center of the next.

OPEN VALLEY: roof valley where shingles do not cross the valley intersection; flashing does.

PARAPET: a low wall or barrier at the edge of a balcony or roof.

PARGING: a surface coat of cement over masonry to help waterproof it.

PASSIVE SOLAR COLLECTOR: system for collecting solar energy  without use of mechanical devices such as fans or pumps.

PITCH: the angle of slope of a roof. (i.e. 4 inches rise in a 12 inch area equals a 4/12 pitch roof).

PLATE: horizontal framing member at the top or bottom of a wall.

PLENUM: a chamber that can serve as a distribution area for heating or cooling systems, generally located between a false ceiling and the actual ceiling.

POLARITY: the electrical charge, either positive or negative, of an electric service terminal.

PRESSURE-TREATED WOOD: wood that has been injected with preservative under pressure.

RACKING: distortion of a building surface from the rectangular plane.

RADIANT HEATING: method of heating whereby much of the heat transfer is accomplished by radiation through space from warm building,   surfaces such as floors, walls, or ceilings.

RAFTER: roof beam running in the direction of the slope.

REBAR: steel bars used in concrete, to strengthen it and tie it together.

RELATIVE HUMIDITY: amount of   water vapor in air compared with the maximum amount possible, expressed as a percentage.

RETROFIT: to upgrade a structure using modem materials.

RIDGE: highest point of a roof.

RIDGE BOARD: A board running the length of the ridge of the roof, to which rafters are fastened.

RIDGE VENT: continuous, prefabricated outlet ventilator placed over an opening at the ridge of the roof line to allow the release of air.

RISE: vertical increase in one step of a stair.

RISER: vertical board between stair treads. Also a vertical plumbing pipe.

ROLL ROOFING: low-cost asphalt roofing in roll form.

R-VALUE: measurement of a materials resistance to heat.

SASH: frame holding the panes of glass in a window or door.

SEALANT: compressible material used to seal building joints, etc.

SEALED GLASS: panes of glass with a sealed air space between.

SERVICE DROP: service entry wiring from the utility pole to the meter.

SHEATHING: layer of boards over the framing but under the finish.

SHEETROCK: plasterboard compound of a core of gypsum between two sheets of heavy paper.

SHIM: thin, tapered piece of wood or metal, used to level something.

SHINGLE: small, thin piece of material, often tapered, for laying in overlapping rows as in roofing or siding.

SILL: lowest horizontal member in a frame. Also the bottom piece of the window rough opening.

SKYLIGHT: a window in a roof or ceiling.

SLAB-ON-GRADE: concrete slab resting directly on the ground at near grade level.

SOFFIT: underside of a roof overhang, cornice, or stairway.

SPAN: distance between supports.

SPARK ARRESTER: wire mesh device placed atop a chimney to prevent embers from blowing out onto the roof.

STANDING-SEAM: metal roofing technique of folding the upturned edges of adjacent sheets to form a weatherproof seam.

STILE: vertical outside frame member in a door or window sash.

STOOL: interior horizontal, flat molding at the bottom of a window.  

STOP (MOLDING): thin molding for stopping doors on closure or holding window sash in place.

STRINGER: side member of stairway into which the stair treads and risers are attached and set.

STUCCO: a wet plaster finish, specifically designed for exterior use; popular as an outside wall surface or   as a siding material.

STUD: vertical framing member to which wall sheathing and siding are    attached.

SUBFLOOR: first floor laid over the floor joists. The subfloor may also serve as the finish floor.

TAB: exposed portion of an asphalt shingle between the cutouts.

TAPING: finishing gypsum drywall joints with paper tape and joint compound.

TEMPERED GLASS: glass that has been cooled rapidly to produce surface tension; the result is a stronger-than normal glass that shatters into relatively harmless cubical fragments when broken.

TRESHHOLD: a wooden or metal strip under an outside door; the entrance to a building.

THIMBLE: protective device installed in a combustible wall through which a stovepipe passes.

TOE NAILING: nailing a wood joint at an angle for additional strength.

TONGUE AND GROOVE: flooring and sheathing joint in which the tongue of one piece meets a groove in a mating piece.

TRAP: a curved section of drain pipes used under plumbing fixtures to "trap" waste material or debris.

TREAD: horizontal part of a step.

TRUSS: framing structure for spanning great distances, in which every member is purely in tension or compression.

UNDERLAYMENT: sheet material or wood providing a smooth, sound base for the finished floor above.

VAPOR BARRIER: material or surface designed to block diffusion of water vapor.

VERMICULITE: type of insulation.

WATER HAMMER: sound made by supply pipes when water is suddenly stopped by the quick closing of a valve.