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Glossary Of Construction Terms
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

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Air-dried lumber.
Lumber that has been piled in yards or sheds for any length of time. For the United States as a whole, the minimum moisture content of thoroughly air-dried lumber is 12 to 15 percent and the average is somewhat higher. In the South, air-dried lumber may be no lower than 19 percent.

Airway.
A space between roof insulation and roof boards for movement of air.

Anchor bolts.
Bolts to secure a wooden sill plate to concrete or masonry floor or wall.

Apron.
The flat member of the inside trim of a window placed against the wall immediately beneath the stool.

Astragal.
A molding attached to one of a pair of swinging doors, against which the other door strikes.

Attic ventilators.
In houses, screened openings provided to ventilate an attic space. They are located in the soffit area as inlet ventilators and in the gable end or along the ridge as outlet ventilators. They can also consist of power-driven fans used as an exhaust system.
(See also Louver.)

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Balusters.
Usually small vertical members in a railing used between a top rail and the stair treads or a bottom rail.

Balustrade.
A railing made up of balusters, top rail, and sometimes bottom rail, used on the edge of stairs, balconies and porches.

Barge board.
A decorative board covering the projecting rafter (fly rafter) of the gable end. At the cornice, this member is a fascia board.

Base or baseboard.
A board placed against the wall around a room next to the floor to finish properly between floor and drywall.

Base shoe.
Molding used next to the floor on interior baseboard.

Batter board.
One of a pair of horizontal boards nailed to posts set at the corners of an excavation, used to indicated the desired level, also as a fastening for stretched strings to indicate outlines of foundation walls.

Bay window.
Any window spacing projecting outward from the walls of a building, either square or polygonal in plan.

Beam.
A structural member transversely supporting a board.

Bearing partition.
A partition that supports any vertical load in addition to its own weight.

Bearing wall.
A wall that supports any vertical load in addition to its own weight.

Blind-nailing.
Nailing in such a way that the nailheads are not visible on the face of the work–usually at the tongue of matched boards.

Boiled linseed oil.
Linseed oil in which enough lead, manganese, or cobalt salts have been incorporated to make the oil harden more rapidly when spread in thin coatings.

Brace.
An inclined piece of framing lumber applied to wall or floor to stiffen the structure. Often used on walls as temporary bracing until framing has been completed.

Brick veneer.
Facing of brick laid against and fastened to sheathing of a frame wall or tile wall construction.

Bridging.
Small wood or metal members that are inserted in a diagonal position between the floor joists at midspan to act both as tension and compression members for the purpose of bracing the joists and spreading the action loads.

Built-up roof.
Roofing composed of three to five layers of asphalt felt laminated with coal, tar, pitch or asphalt. The top is finished with crusted slag or gravel. Generally used on flat or low pitched roofs.

Butt joint.
The junction where the end of two timbers or other members meet in a square-cut joint.

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Cap.
The upper member of a column, pilaster, door cornice, molding and the like.

Casing.
Molding of various widths and thickness used to trim door and window openings at the jambs.

Collar beam.
Normal one-or-two-inch-thick members connecting opposite roof rafters. They serve to stiffen the roof structure.

Column.
In architecture: A perpendicular supporting member, circular or rectangular in section, usually consisting of a base, shaft and capital. In engineering: A vertical structural compression member that supports loads acting in the direction of its longitudinal axis.

Condensation.
In a building: Beads or drops of water (and frequently frost in extremely cold weather) that accumulate on the inside of the exterior covering of a building when warm, moisture-laden air from the interior reaches a point where the temperature no longer permits the air to sustain the moisture it holds. Use of louvers or attic ventilators will reduce moisture condensation in attics. A vapor barrier under the gypsum lath or dry wall on exposed walls will reduce condensation in them.

Conduit, electrical.
A pipe, usually metal, in which wire is installed.

Construction, frame.
A type of construction in which the structural parts are wood or depend upon wood frame for support. In codes, if masonry veneer is applied to the exterior walls, the classification of this type of construction is usually unchanged.

Coped joint.
See Scribing.

Corner bead.
A strip of formed sheet metal, sometimes combined with a strip of metal lath, placed on corners to reinforce them. Also, a strip of wood finish three-quarters-round or angular placed over a drywall corner for protection.

Corner boards.
Used as trim for the external corners of a house or other frame structure against which the ends of the siding are finished.

Corner braces.
Diagonal braces at the corners of frame structures to stiffen and strengthen the wall.

Cornice.
Overhang of a pitched roof at the eave line, usually consisting of facia board, a soffit for a closed cornice, and appropriate moldings.

Cornice return.
That portion of the cornice that returns on the gable-end of the house.

Counterflashing.
A flashing usually used on chimneys at the roofline to cover shingle flashing and to prevent moisture entry.

Cove molding.
A molding with a concave face used as trim or to finish interior corners.

Crawl space.
A shallow space below the living quarters of a basementless house, normally enclosed by the foundation wall.

Cricket.
A small drainage-diverting roof structure of single or double slope placed at the junction of larger surfaces that meet at an angle, such as above a chimney.

Cross-bridging.
Diagonal bracing between adjacent floor joists, placed near the center of the joist span to prevent joists from twisting.

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Dado.
A rectangular groove across the width of a board or plank. In interior decoration, a special type of wall treatment.

Decay.
Disintegration of wood or other substance through the action of fungi.

Deck paint.
Enamel with a high degree of resistance to mechanical wear, designed for use on such surfaces as porch floors.

Density.
The mass substance in a unit volume. When expressed in the metric system, it is numerically equal to the specific gravity of the same substance.

Dewpoint.
Temperature at which a vapor begins to deposit as a liquid. Applies especially to water in the atmosphere.

Dimension.
See Lumber dimension.

Direct nailing.
To nail perpendicular to the initial surface or to the junction of the pieces joined. Also termed face nailing.

Doorjamb, interior.
The surrounding case into which and out of which a door closes and opens. It consists of two upright pieces, called side jambs, and a horizontal head jamb.

Dormer.
An opening in a sloping roof, the framing of which projects out to form a vertical wall suitable for windows or other openings.

Downspout.
A pipe, usually of metal, for carrying rainwater from roof gutters.

Drip.
a) A member of a cornice or other horizontal exterior finish course that has a projection beyond the other parts for throwing off water. b) 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.

Drip cap.
A molding placed on the exterior topside of a door or window frame to cause water to drip beyond the outside of the frame.

Dry wall.
Interior covering materials such as gypsum board or plywood, which is applied in large sheets or panels.

Ducts.
In a house, usually round or rectangular metal pipes for distributing warm air from the heating plant to rooms or air from a conditioning device or as cold air returns. Ducts are also made of composition materials.

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Eaves.
The margin or lower part of a roof projecting over the wall.

Expansion joint.
A bituminous fiber strip used to separate blocks or units of concrete to prevent cracking due to expansion as a result of temperature changes. Also used on concrete slabs.

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Facia or fascia.
A flat board, band or face used sometimes by itself but usually in combination with moldings, often located at the outer face of the cornice.

Filler (wood).
A heavily pigmented preparation used for filling and leveling off the pores in open-pored woods.

Fire-resistive.
In the absence of a specific ruling by the authority having jurisdiction, applies to materials for construction not combustible in the temperatures of ordinary fires and that will withstand such fires without serious impairment of their usefulness for at least one hour.

Fire-retardant chemical.
A chemical or preparation of chemicals used to reduce flammability or to retard spread of flame.

Fire stop.
A solid, tight closure of a concealed space, placed to prevent the spread of fire and smoke through such a space. In a frame wall, this will usually consist of two-by-four cross blocking between studs.

Flashing.
Sheet metal or other material used in roof and wall construction to protect a building from water seepage.

Flat paint.
An interior paint that combines a high proportion of pigment and dries to a flat or lusterless finish.

Flue.
The space or passage in a chimney through which smoke, gas or fumes ascend. Each passage is called a flue, which together with any others and the surrounding masonry make up the chimney.

Flue lining.
Fire clay or terra-cotta pipe, round or square, usually made in all ordinary flue sizes and in two-foot lengths, used for the inner lining of chimneys with the brick or masonry work around the outside. Flue lining in chimneys runs from about a foot below the flue connection to the top of the chimney.

Fly rafters.
End rafters of the gable overhang supported by roof sheathing and lookouts.

Footing.
A masonry section, usually concrete, in a rectangular form wider than the bottom of the foundation wall or pier it supports.

Foundation.
The supporting portion of a structure below the first-floor construction, or below grade, including the footings.

Framing, balloon.
A system of framing a building in which all vertical structural elements of the bearing walls and partitions consist of single pieces extending from the top of the foundation sill plate to the roofplate and to which all floor joists are fastened.

Framing, platform.
A system of framing a building in which floor joists of each story rest on the top plates of the story below or on the foundations sill for the first story, and the bearing walls and partitions rest on the subfloor of each story.

Frieze.
In house construction, a horizontal member connects the top of the siding with the soffit of the cornice.

Frostline.
The depth of frost penetration in soil. This depth varies in different parts of the country. Footings should be placed below this depth to prevent movement.

Fungi, wood.
Microscopic plants that live in damp wood and cause mold, stain and decay.

Fungicide.
A chemical that is poisonous to fungi.

Furring.
Strips of wood or metal applied to a wall or other surface to even it and normally serve as a fastening base for finish material.

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Gable.
In house construction, the portion of the roof above the eave line of a double-sloped roof.

Gable end.
An end wall having a gable.

Gloss enamel.
A finishing material made of varnish and sufficient pigments to provide opacity. Such enamel forms a hard coating with maximum smoothness of surface and a high degree of gloss.

Gloss (paint or enamel).
A paint or enamel that contains a relatively low proportion of pigment and dries to a sheen or luster.

Girder.
A large principal beam of wood or steel used to support concentrated loads at isolated points along its length.

Grain.
The direction, size, arrangement, appearance, or quality of the fibers in the wood.

Grain, edge (vertical).
Edge-grain lumber has been sawed parallel to the pith of the log and approximately at right angles of the growth rings, i.e., the rings form an angle of 45 degrees or more with the surface of the piece.

Grain, flat.
Flat-grain lumber has been sawed parallel to the pith of the log and approximately tangent to the growth rings, i.e.; the rings form an angle of less than 45 degrees with the surface of the piece.

Grain, quartersawn.
Another term for edge grain.

Grout.
Mortar made of such consistency (by adding water) that it will just flow into the joints and cavities of the masonry work and fill them solid.

Gusset.
A flat wood, plywood or similar type member used to provide a connection at intersection of wood members. Most commonly used at joints of wood trusses. They are fastened by nails, screws, bolts or adhesives.

Gutter or eave trough.
A shallow channel or conduit of metal or wood set below and along the eaves of a house to catch and carry off rainwater from the roof.

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Header
a) A beam placed perpendicular to joists and to which joists are nailed in framing for chimney, stairway, or other opening. b) A wood lintel.

Hearth.
The inner or out floor of a fireplace, usually made of brick, tile or stone.

Heartwood.
The wood extending from the pith to the sapwood, the cells of which no longer participate in the life process of the tree.

Hip.
The external angle formed by the meeting of two sloping sides of a building.

Hip roof.
A roof that rises by inclined planes from all four sides of a building.

Humidifier.
A device designed to increase the humidity within a room or a house by means of the discharge of water vapor. They may consist of individual room-size units or large units attached to the heating plant to condition the entire house.

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I-beam.
A steel beam with a cross section resembling the letter I. It is used for long spans as basement beams or over wide wall openings, such as a double garage door, when wall and roof loads are imposed on the opening.

Insulation board, rigid.
A structural building board made of coarse wood or cane fiber in one-half and 25/32-inch thickness. It can be obtained in various size sheets, in various densities and with several treatments.

Insulation, thermal.
Any material high in resistance to heat transmission that, when placed in the walls, ceiling, or floors of a structure, will reduce the rate of heat flow.

Interior finish.
Material used to cover the interior framed areas, or materials of walls and ceilings.

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Jack rafter.
A rafter that spans the distance from the wallplate to a hip, or from a valley to a ridge.

Jamb.
The side and head lining of a doorway, window or other opening.

Joint.
The space between the adjacent surface of two members or components joined and held together by nails, flue, cement, mortar or other means.

Joint cement.
A powder that is usually mixed with water and used for joint treatment in gypsum-wallboard finish. Often called “spackle.”

Joist.
One of a series of parallel beams, usually two inches in thickness, used to support floor and ceiling loads and supported in turn by larger beams, girders or bearing walls.

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Kiln-dried lumber.
Lumber that has been kiln dried often to a moisture content of six to 12 percent. Common varieties of softwood lumber, such as framing lumber are dried to a somewhat higher moisture content.

Knot.
In lumber, the portion of a branch or limb of a tree that appears on the edge or face of the piece.