Glossary of Construction Terminology



jamb - The frame in which a door or window sits.

joint - The space or opening between two or more adjoining surfaces.

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

joist - The horizontal framing members that support the floors.

joist hanger - A metal "U" shaped item used to support the end of a floor joist and attached with hardened nails to another bearing joist or beam.


keeper - The metal latch plate in a door frame into which a doorknob plunger latches.

keyless - A plastic or porcelain light fixture, sometimes operated by a pull string. Generally found in basements, crawl spaces and attic areas.

kiln dried lumber - Lumber that has been kiln dried often to a moisture content of 6 to 12 percent. Common varieties of softwood lumber, such as framing lumber are dried to a somewhat higher moisture content.

kilowatt (kw) - One thousand watts. A kilowatt hour is the base unit used in measuring electrical consumption.

king stud - The vertical "2 X's" frame lumber (left and right) of a window or door opening, and runs continuously from the bottom sole plate to the top plate.

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


laminating - Bonding together two or more layers of materials.

landing - A platform between flights of stairs or at the termination of a flight of stairs.

lap - To extend one material partially over another; the distance so extended.

lath - A building material of wood, metal, gypsum, or insulating board that is fastened to the frame of a building to act as a plaster base.

lattice - A framework of crossed wood or metal strips.

lean-to-roof - The sloping roof of a building addition having its rafters or supports pitched against and supported by the adjoining wall of a building.

ledger (for a structural floor) - The wooden perimeter frame lumber member that bolts onto the face of a foundation wall and supports the wood structural floor.

ledger strip - A strip of lumber nailed along the bottom of the side of a girder on which joists rest.

level - True horizontal. Also a tool used to determine level.

lien - An encumbrance that usually makes real or personal property the security for payment of a debt or discharge of an obligation.

light - Space in a window sash for a single pane of glass. Also, a pane of glass.

limit switch - A safety control that automatically shuts off a furnace if it gets too hot. Must also control blower cycles.

lintel (or header) - A horizontal structural member that supports the load over an opening such as a door or window.

live load - Loads produced by use and occupancy of the building or other structure and do not include construction or environmental loads such as wind load, ice load, rain load, seismic load, or dead load.

load bearing wall - Includes all exterior walls and any interior wall that is aligned above a support beam or girder. Normally, any wall that has a double horizontal top plate.

lookout - A short wood bracket or cantilever that supports an overhang portion of a roof.

louver - An opening with a series of horizontal slats so arranged as to permit ventilation but to exclude rain, snow, light, or insects.

lumens - Unit of measure for total light output. The amount of light falling on a surface of one square foot.