Glossary

Home Improvement Glossary

The definitions in this glossary are provided as an aid to assist you with unfamiliar terms. Tools, products, materials, techniques, building codes and local regulations vary; therefore the reader must always exercise reasonable caution, follow applicable codes and regulations, and is urged to consult with a professional if in doubt about any terms or procedures.

Scroll to find the definition you’re looking for or click the first letter of the term.

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

ABS pipe: Black plastic pipe sometimes used as drainage pipe in plumbing systems.

Air Space: The area between insulation facing and interior of exterior wall coverings. For best results, manufacturers recommend filling this space with insulation and allowing at least 3/4″ air space in installing reflective faced insulation.

Amp: A measure of the amount of electrical current going through a circuit at any given time. Also see volt and watt.

B

Back-up system: Auxiliary heating equipment that kicks in when the main unit–usually a heat pump or solar setup–can’t handle the full load.

Balancing: Fine-tuning the air flow of a heating/cooling system to even up the delivery through a home.

Balusters: Spindles that help support a handrail.

Bat: A half-brick.

Batt: A section of fiber-glass or rock-wool insulation measuring 15 or 23 inches wide by four to eight feet long.

Batten: A narrow strip used to cover joints between boards or panels.

Beam: A horizontal support member. Also see post and post-and-beam.

Bearing wall: An interior or exterior wall that helps support the roof or the floor joists above.

Biscuit: n. a football shaped wafer of wood, usually compressed beech, designed to swell with the application of glue and used to key and strengthen glue joints in woodworking. Plastic biscuits are also used in special applications such as joining panels of special composition countertop material. v. to join by use of biscuits.

Blankets: Fiber-glass or rock-wool insulation that comes in long rolls 15 or 23 inches wide.

Blocking: Small wood pieces to brace framing members or to provide a nailing base for gypsum board or paneling.

Board Foot: A unit of measure for lumber equal to 1 inch thick by 12 inches wide by 12 inches long. Examples:
1″ x 12″ x 16′ = 16 board feet
2″ x 12″ x 16′ = 32 board feet

Bond: The pattern in which bricks or other masonry units are laid. Also, the cementing action of an adhesive.

Bottom chord: The lower or bottom member of a truss.

Bracing: In a stick-built roof system it is the W-shaped structural member which provides support to the roof rafter. A piece of dimensional lumber or metal, used diagonally on the corner of a home. See corner brace.

Brick veneer: a four-inch brick wall used to provide an exterior finish for a house.

BTU (British Thermal Unit): The amount of heat needed to raise one pound of water one degree Fahrenheit. Heating and cooling equipment commonly is rated by the BTUs it can deliver or absorb. Also see heat gain and heat loss.

Building codes: Community ordinances governing the manner in which a home may be constructed or modified. Most codes primarily concern themselves with fire and health, with separate sections relating to electrical, plumbing, and structural work. Also see zoning.

Butt: To place materials end-to-end or end-to-edge without overlapping.

Butt hinge: The most common type. One leaf attaches to the door’s edge, the other to its jamb.

C

Cantilever: A beam or beams projecting beyond a support member.

Casing: Trim work around a door, window, or other opening.

Caulk: Any of a variety of different compounds used to seal seams and joints against infiltration of water and air.

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.

Cement: A powder that serves as the binding element in concrete and mortar. Also, any adhesive.

Ceramic tile: A man-made or machine-made clay tile used to finish a floor or wall.

CFM (cubic feet per minute): A rating that expresses the amount of air a blower or fan can move.

Chalking: The tendency of some exterior paints to gradually erode away over a period of time.

Circuit breaker: A protective switch that automatically shuts off current in the event of a short or overload. Also see fuse, short circuit.

Class “A:” Optimum fire rating issued by Underwriter’s Laboratories on roofing. The building code in some areas requires this type of roofing for fire safety.

Class “C:” Minimum fire rating issued by the Underwriters’ Laboratories for roofing materials.

Compression web: A member of a truss which connects the bottom and top chords and provides downward support.

Compressor: The part of a cooling unit or heat pump that compresses refrigerant gas so it can absorb heat.

Concrete: A basic building and paving material made by mixing water with sand, gravel, and cement. Also see mortar and cement.

Concrete block: A hollow or solid unit made of concrete used in building construction.

Condensing unit: The outdoor segment of a cooling system. It includes a compressor and condensing coil designed to give off heat. Also see evaporator coil

Conduit: A metal tube used to run, house or contain electrical wire.

Convection: Currents created by heating air, which then rises and pulls cooler air behind it. Also see radiation.

COP (coefficient of performance): A measure of the efficiency of any heating unit– arrived at by dividing its output in BTUs by its input in BTUs.

Coping: A cap at the top of a wall that’s rounded or beveled to shed water. Also, a curved cut made so that one contoured moulding can join neatly with another.

Corner bead: Lightweight, perforated metal angle used to reinforce outside corners in drywall construction.

Corner assembly: The framing members used to change direction in an interior-exterior wall.

Corner brace: Diagonal supports set into studs to reinforce the area where a wall changes direction in a frame structure. In many areas plywood is used.

Cornice: The projection from a building that crowns or finishes the edge. Horizontal projection at the top of exterior wall which finishes the eaves of a building.

Courses: Parallel layers of building materials such as bricks, shingles, or siding laid up horizontally.

Cove: A concave curve where vertical and horizontal surfaces join.

Crawl space: Space between floor and ground of a house or building.

Cripples: Short studs above or below a door or window opening.

Crown: Paving slightly humped so that water will run off. Also a contoured moulding sometimes installed at the junctures of walls and ceilings.

Crown: Most boards have a slight bow to one edge. The high side of the bow is called the crown or crown edge.

Cupping: A type of warping that causes boards to curl up at their edges.

D

Dado: n. a groove cut into a board or panel intended to receive the edge of a connecting board or panel. v. to cut a dado.

Damper: A valve inside a duct or flue that can be used to slow or stop the flow of air or smoke.

Dampproofing: The coating applied to the exterior of a foundation wall with a waterproofing material such as foundation coating.

Dead bolt: A locking device that can be activated only with a key or thumb turn. Unlike a latch, which has a beveled tongue, dead bolts have square ends.

Decking: The material installed over the supporting framing members to which the roofing material is applied.

Determinate:A plant that, by artificial or natural means, produces all of its flowers or fruit at the same time.

Directional Light: Light intensity at the center of the beam. Used for flood and spot light bulbs types.

Do-it-yourself (DIY): The process of doing any project by oneself. Some may traditionally have been contracted out to a professional or in the case of a klutz done by one’s spouse or father-in-law. If necessity is the mother of invention it is also the father of DIY.

Double cylinder: A type of lock that must be operated with a key from inside as well as outside.

Double hung window: A window that has a top sash and bottom sash, both of which move up and down.

Double pane window: Two panes of glass sealed at the edges to create dead air space. The sealed air acts as an insulator.

Drain tile: A perforated, corrugated plastic pipe laid at the bottom of the foundation wall used to drain excess water away from the foundation. It prevents water from seeping through the foundation wall.

Drying in: The construction process generally considered to be from the foundation plate up through the application of exterior finish materials.

Dry wall: A masonry wall laid up without mortar.

Drywall: A basic interior building material consisting of big sheets of pressed gypsum faced with heavy paper on both sides. Also known as gypsum board, plasterboard, and Sheetrock (a trade name).

DWV (drain-waste-vent): The section of a plumbing system that carries water and sewer gases out of a home.

E

EER (energy efficiency ratio): A measure of cooling efficiency computer by dividing a cooling unit’s output in BTUs by its input in watts.

EPACT: Energy Policy Act. Government regulations promoting the use of energy efficient lighting by prohibiting the manufacturing or importing of certain inefficient bulb types.

Efflorescence: A whitish powder sometimes exuded by the mortar joints in masonry work. It’s caused by salts rising to the surface.

Elbow (ell): 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 in your home. Also see condensing unit.

Expansion joint: Flexible material between two surfaces that enables joints to ride out differing rates of expansion and contraction.

F

Facing brick: The brick used and exposed on the outside of a wall. Usually these have a finished texture.

Fascia board: Horizontal trim attached to the outside ends of rafters or to the top of an exterior wall.

Felt: Highly absorbent fiber material saturated and impregnated with asphalt and used as backing for rock surfaced roofing materials. Made from organic, asbestos or glass fibers to result in a strong, absorbent and flexible product.

Female: Any part, such as a nut or fitting, into which another (male) part can be inserted. Internal threads are female.

Finger joint: A manufacturing process of interlocking two shorter pieces of wood end to end to create a longer piece of dimensional lumber or moulding. Often used in jambs and casings.

Finish roof: Shingles, asphalt, etc. used to cover the exterior of a roof.

Fire brick: Brick made of refractory ceramic material which will resist high temperatures. Used in a fireplace.

Fire blocking: Short horizontal members sometimes nailed between studs, usually about halfway up a wall.

Firebrick: Highly heat-resistant brick for lining fireplaces and boilers.

Flashing: Metal or composition strips used to seal junctions between roofing and other surfaces, or in the valleys between different slopes.

Floating: The next-to-last stage in concrete work, when you smooth off the job and bring water to the surface.

Floor girder (girder): A horizontal beam supporting the floor joists.

Floor joist: One of a series of parallel framing members used to support floor loads and supported in turn by larger beams, girders, bearing walls or foundation.

Flue: A pipe or other channel that carries off smoke and combustion gasses to the outside air.

Fluorescent lamp: A light source that instead of “burning” as incandescent bulbs do, uses an ionization process to produce ultraviolet radiation. This turns into visible light when it hits a coating on the tube’s inner surface.

Footing: The base on which a masonry wall or other support rests. It spreads out the load to prevent settling.

Framing: The wood skeleton of a building.

Framing in: The construction process generally considered to be from the foundation plate up to the application of exterior finish materials.

Frost line: The depth to which the ground freezes below the surface. This varies from region to region, and determines how deep footings must be.

Furring: Lightweight wood or metal strips that even up a wall or ceiling for paneling or drywall. On masonry, furring provides a surface on which to nail.

Fuse: A safety device designed to burn out if a circuit shorts or overloads. This protects against fire. Also see circuit breaker , short circuit.

G

Gable: The triangular end of an exterior wall above the eaves of a pitched roof.

Gable roof: A roof which slopes from two sides only.

Gable stud: The stud at the gable of a roof where the exterior finish is applied.

Gang nail plate: A steel plate attached to both sides at each joint of a truss.

Gate valve: A valve that lets you completely stop–but not modulate–the flow within a pipe. Also see globe valve.

GFCI (ground fault circuit interrupter): An electrical safety device that instantly shuts down a circuit if a leakage occurs. Codes commonly require them on bathroom and outdoor circuits.

Girder (floor girder): A horizontal beam supporting the floor joists.

Glazing: The process of installing glass, which commonly is secured with glazier’s points and glazing compound.

Globe valve: A valve that lets you adjust the flow of water to any rate between fully on and fully off. Also see gate valve.

Grade: Ground level, or the elevation at any given point.

Grain: The direction of fibers in lumber or other materials.

Ground: Refers to electricity’s habit of seeking the shortest route to earth. Neutral wires carry it there in all circuits. An additional grounding wire–or the sheathing of metal-clad cable or conduit–protects against shock if the neutral leg is interrupted.

Grout: Thin mortar that fills the joints between tiles or other masonry.

Gypsum board: See drywall.

H

Hardboard: A manufactured building material made by pressing wood fibers into sheet goods.

Header: Heavier framing–usually doubled and laid on edge– at the top of a window, door, or other opening. In masonry, a header course of bricks or stones laid on edge provides strength.

Heat gain: Heat coming into a home from sources other than its heating/cooling system. Most gains come from the sun.

Heat loss: Heat escaping from a home usually to outside air. Heat gains and losses are expressed in BTUs per hour.

Heat pump: A reversible air conditioner that can extract heat from outside as well as inside air.

HID (high intensity discharge) lamp: A lamp that operates in the same way as a fluorescent tube, but that has a bulb like incandescent lamps.

Hip roof: A roof with four sloping sides.

Hoop stake: A long, thin, metal post with a perpendicular ring of wire at the top, which serves as a support for tall-growing flowers.

Hot wire: The wire that carries electrical energy to a receptacle or other device–in contrast to a neutral, which carries electricity away again. Also see ground.

I

Incandescent lamp: A lamp employing an electrically charged metal filament that glows at white heat.

Inside corner: The point at which two walls form an internal angle, as in the corner of a room.

Interior finish: Any coverings that cover the interior walls of a house. Examples are drywall, paneling, etc.

Jack post: A type of structural support made of metal, which can be raised or lowered through a series of pins and a screw to meet the height required. Basically used as a replacement for an old supporting member in a building.

Jambs: The top and sides of a door, window, or other opening. Includes studs as well as the frame and trim.

Joint compound: A synthetic-based formula used in combination with paper tape to conceal joints between drywall panels. Also see taping.

Joists: Horizontal framing members that support a floor and/or ceiling.

K

Kilowatt (kw): One thousand watts. A kilowatt hour is the base unit used in measuring electrical consumption. Also see watt.

L

Laminating: Bonding together two or more layers of materials.

Latch: A beveled metal tongue operated by a spring-loaded knob or lever. The tongue’s bevel lets you close the door and engage the locking mechanism, if any, without using a key. Contrasts with dead bolt.

Lath: Strips of wood, expanded metal mesh, or a special drywall that serve as a base for plaster or stucco.

Level: True horizontal. Also a tool used to determine level.

Life: The average number of hours a bulb will burn.

Lighting Efficiency: Expressed as Lumens per Watt. A measure of efficiency similar to miles per gallon. The best choice is usually the highest light output (Lumens) for the least power consumed (Watts).

Limit switch: A safety control that automatically shuts off a furnace if it gets too hot. Most also control blower cycles.

Lineal foot: A unit of measure for lumber equal to any thickness by any width by 12 inches long. Example: 2″ x 6″ x 14′ = 14 lineal feet. 1″ x 6″ x 14′ = 14 lineal feet.

Lintel: A load-bearing beam over an opening in masonry, such as a door or fireplace.

Lumens: Unit of measure for total light output.

M

Male: Any part, such as a bolt, designed to fit into another (female) part. External threads are male.

Masonry: Brick, tile, stone, concrete units, etc., or combinations thereof, bonded with mortar. Something constructed using bricks or stones.

Millwork: Woodwork such as doors, sashes and trim that have been shaped, usually by a milling machine.

Miter: A joint formed by beveling the edges or ends of two pieces at 45-degree angles, then fitting them together to make a 90-degree angle.

Mortar: The bonding agent between bricks, blocks, or other masonry units. Consists of water, sand, and cement–but not gravel. Also see concrete.

Mortise: A hole, slot, groove, or other recess into which another element fits. Most hinges, for example, are mortised so they lie flush.

Muriatic acid: Commonly used as a brick cleaner after masonry work is completed.

CEC (Canadian Electrical Code): A set of rules governing safe wiring methods. Local codes–which are backed by law–may differ from the NEC in some ways.

Neutral wire: Usually color-coded white, this carries electricity from an outlet back to ground. Also see hot wire and ground.

Newel post: A post at the bottom, landing, or top of a staircase to which the handrail is secured.

No-hub: A clamp-and-sleeve system for joining together cast-iron drainage pipes. Older hub-type pipes had to be leaded at all joints.

OC (on-center): The distance from the center of one regularly spaced framing member to the next. Studs and joists are commonly 16 or 24 inches OC.

Outside corner: The point at which two walls form an external angle, one you usually can walk around.

Overhang: Outward projecting eave-soffit area of a roof; the part of the roof that hangs out or over the outside wall.

Panel: Wood, glass, plastic, or other material set into a frame, such as in a door. Also, a large, flat, rectangular building material such as plywood, hardboard, or drywall.

Partition: An interior dividing wall. Partitions may or may not be bearing.

Paving: Materials–commonly masonry–laid down to make a firm, even surface.

Payback: The length of time before the money you save with new equipment, insulation, etc. will equal your original investment. Commonly used in evaluating energy-related items.

Pier: A masonry post. Piers often serve as footings for wood or steel posts.

Pilot hole: A small-diameter hole that guides a nail or screw.

Pilot light: A small, continuous flame that ignites gas or oil burners when needed.

Pitch (roof): The slope of a roof expressed in feet rise per foot of run.

Plenum: The main hot-air supply duct leading from a furnace.

Plumb: True vertical. Also see level.

Plumb bob: A lead weight attached to a string. It is the tool used in determining plumb.

Plywood: A building panel made by gluing together thin layers of wood. Alternating grain directions from one layer to the next adds strength.

Post: Any vertical support member.

Post-and-beam: A basic building method that uses just a few hefty posts and beams to support an entire structure. Contrasts with stud framing.

Pressure-treated wood: Lumber that has been saturated with a preservative.

Primer: A first coating formulated to seal raw surfaces and hold succeeding finish coats.

Propagate: To grow new plants from old ones by using one of a variety of methods.

PVC (polyvinyl chloride): A type of plastic pipe that’s suitable for cold water, but not hot.

R

Rabbet: n. a recess cut into the edge of a board into which another piece fits to form a rabbet joint. v. to cut a rabbet. To join by means of a rabbet joint.

Radiation: Energy transmitted from a heat source to the air around it. So-called “radiators” actually depend more on convection than radiation.

Rafters: Parallel framing members that support a roof.

Rail : Any relatively lightweight horizontal element, especially those found in fences. Also the horizontal pieces between panels in a panel door.

Rake board : Fascia board that covers the far left and right rafters on a roof.

Retaining wall: A barrier created with stones, timbers, or boards, prevent the erosion of soil on steep slopes.

Ridge board: The topmost beam at the peak of a roof to which rafters tie.

Rim joist: The outermost joist in a structure’s floor framing.

Rise: The vertical distance from one point to another above it; a measurement you need in planning a stairway or ramp. Also see run.

Riser: The upright piece between two stairsteps. Also see tread.

Roof decking: Subsurface material on which roof shingles or built up roofing is applied. Some roof decking is made with one side finished to serve as both roof deck and finished ceiling.

Roof sheathing: The sheets or boards for sheathing over rafters. Also called roof decking, roof underlayment.

Roofing cement: A pliable asphalt- or plastic-based compound used as an adhesive and to seal flashings, minor leaks, etc.

Rough opening: The openings in walls and partitions for doors and windows as formed by the framing members.

Rough sill: The framing member at the bottom of a rough opening for a window. It is attached to the cripple studs below the rough opening.

Roughing-in: The initial stage of a plumbing, electrical, carpentry, or other project, when all components that won’t be seen after the second finishing phase are assembled.

Run: The horizontal distance a ramp or stairway traverses. Also see rise.

R-value : A measure of the resistance an insulating material offers to heat transfer. The higher the R-value, the more effective the insulation.

S

Saddle: The plate at the bottom of some–usually exterior–door openings. Sometimes called a threshold.

Sash: The openable part of a window, consisting of a frame and one or more panes of glass.

Screed: Leveling concrete, sand or other material by pulling a board pipe or other straightedge across it in a sawing motion.

Setback: The distance a home must be built from property lines (this is dictated by local zoning ordinances. Also a temporary change in a thermostat’s setting.

Settlement: Shifts in a structure, usually caused by freeze-thaw cycles underground.

Sheathing: The first covering on a roof or exterior wall, usually fastened directly to rafters or studs.

Sheetrock: A type of wall and ceiling finish made from ground gypsum covered with a paper finish. Common sizes are 4′x8′, 4′x12′. Most commonly used as a wall finish that is then painted or wallpapered. Also, drywall, gypsum wall board.

Shim: Thin material inserted to make adjustments in level or plumb. Tapered wood shingles make excellent shims in carpentry work.

Shingle: A covering used to finish the sides or the roof of a house.

Shoe moulding: Strips of quarter round commonly used where a baseboard meets the floor. Also sometimes known as base shoe.

Short circuit: A situation that occurs when hot and neutral wires come in contact with each other. Fuses and circuit breakers protect against fire that could result from a short.

Siding: The finish material of an exterior wall. Types include wood, aluminum, vinyl and hardboard.

Sill: The lowest horizontal piece of window, door, or wall framework.

Sill plate (mudsill): Bottom horizontal member of an exterior wall frame which rests atop foundation, sometimes called mudsill; also sole plate, bottom member of interior wall frame.

Slab (concrete): A term referring to a flat area of concrete.

Slab construction: A build term referring to construction placed on a slab as its foundation.

Sleepers: Boards laid directly over a masonry floor to serve as nailers for plywood, or strip or plank flooring.

Soffit: Covering attached to the underside of eaves or a staircase.

Soil pipe: A large pipe that carries liquid and solid wastes to a sewer or septic tank.

Sole plate: The bottommost horizontal part of a stud partition. When a plate rests on a foundation, it’s called a sill plate.

Spacing: The distance between individual members or shingles in building construction.

Span: The distance between supports, generally walls, for rafters or trusses.

Spandrel: The space between two openings which are one above the other in a wall.

Spec home: A house built before it is sold. The builder speculates that he can sell it at a profit. Sometimes he speculates that he can merely sell it.

Specifications: Written elaboration in specific detail about construction materials and methods; this supplements working drawings.

Square: A situation that exists when two elements are at right angles to each other. Also a tool for checking this. An area of roofing which is 10′ square or comprising 100 square feet.

Staking: A method of supporting tall, upright-growing plants by tying their stems to a wood or metal post.

Stick built: A house built without prefabricated parts. Also called conventional building.

Stile: The vertical upright on either side (and sometimes the center) of a panel door.

Stringer: The side or inclined member of a stair system used to support the treads and risers.

Stops: Mouldings along the inner edges of a door or window frame. Also valves used to shut off water to a fixture.

Strike: The plate on a door frame that engages a latch or dead bolt

Stucco: A mixture of Portland cement, sand, lime and water used to cover cement blocks for decoration purposes.

Stud framing: A building method that distributes structural loads to each of a series of relatively lightweight studs. Contrasts with post-and-beam.

Studs : Vertical 2×3, 2×4, or 2×6 framing members spaced at regular intervals within a wall.

Subfloor: Bottom layer of plywood or boards in a two-layer floor.

T

Take off: A list of materials developed from a set of blueprints.

Taping: The process of covering drywall joints with paper tape and joint compound.

Tee: A T-shaped plumbing fitting.

Terra Cotta: A ceramic material molded into masonry units.

Three-four-five triangle: An easy, mathematical way to check whether a large angle is square. Measure three feet along one side, four feet along the other; if the corner is square, the diagonal distance between those two points will equal five feet.

Threshold: See saddle.

Throat: The opening at the top of a fireplace through which smoke passes enroute to the flue.

Tie (veneer): A metal strip used to tie a brick or masonry wall to the wooden frame wall.

Toenail: To drive nails at an angle.

Ton: A measure of cooling power. One ton equals 12,000 BTU’s.

Tongue and groove: A style of lumber in which the pieces interlock to form a strong solid formation.

Top chord: The upper or top member of a truss.

Top plate: The topmost horizontal element of a stud-frame wall.

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

Treads: The level parts of a staircase. Also see risers.

Treated lumber: A chemical treatment applied to dimension lumber to prevent rot or decay. Used mainly in outdoor decks and other exposed areas.

Trimmers: Studs at either side of a door, window, or other opening that are used to support the header.

Truss: A prefabricated structure made of wood members designed to form a rigid framework for supporting loads over a given span.

Trusses: Pre-engineered and wood frames designed to support roof or floor loads.

U

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

Underlayment: Top layer of plywood (or other material) in a two-layer floor. Provides a smooth base for carpet, tile or sheet flooring.

Union: A plumbing fitting that joins pipes end-to-end so they can be dismantled.

V

Valley: The intersection of two roof slopes.

Vapor barrier: A waterproof membrane in a floor, wall, or ceiling that blocks the transfer of condensation.

Volt (V): A measure of electrical pressure. Volts x amps = watts.

W

Warping: Any distortion in a material.

Watt (W): A measure of the power an electrical device consumes. Watt hours (WH) express the quantity of energy consumed. Also see volt, amp, and kilowatt.

Y

Y (wye): A Y-shaped plumbing fitting.

Z

Zoning: Ordinances regulating the ways in which a property may be used in any given neighborhood. Zoning laws may limit where you can locate a structure. Also see building codes.