Glossary of Construction Terminology



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

mantel - The shelf above a fireplace opening. Also used in reference to the decorative trim around a fireplace opening.

mansard roof - A roof which rises by inclined planes from all four sides of a building. The sloping roofs on all four side have two pitches, the lower pitch, usually very steep and the upper pitch, less steep.

masonry - Stone, brick, concrete, hollow-tile, concrete block, or other similar building units or materials. Normally bonded together with mortar to form a wall or similar mass.

mastic - Heavy-consistency compound that may remain adhesive and pliable with age. Is typically a waterproof compound applied to exterior walls and roof surfaces.

membrane - A generic term relating to a variety of sheet goods used for certain built-up roofing repairs and application.

metal lath - Sheets of metal that are slit to form openings within the lath. Used as a plaster base for walls and ceilings and as reinforcing over other forms of plaster base.

microlam - A manufactured structural wood beam. It is constructed of pressure and adhesive bonded wood strands of wood. They have a higher strength rating than solid sawn lumber. Normally comes in 1-1/2" thickness' and 9-1/2". 11-1/2" and 14" widths.

migration - Spreading or creeping of a constituent of a compound onto/into adjacent surfaces. See bleeding.

millwork - Generally all building materials made of finished wood and manufactured in millwork plants. Includes all doors, window and door frames, blinds, mantels, panelwork, stairway components (ballusters, rail, etc.), moldings, and interior trim. Does not include flooring, ceiling or siding.

mineral spirits - A by-product of petroleum, clear in color, a solvent for asphaltic coatings.

miter joint - The joint of two pieces at an angle that bisects the joining angle. For example, the miter joint at the side and head casing at a door opening is made at a 45 degree angle.

molding - A wood strip having an engraved, decorative surface.

monopost - Adjustable metal column used to support a beam or bearing point. Normally 11 gauge or Schedule 40 metal, and determined by the structural engineer.

mortar - A mixture of cement (or lime) with sand and water used in masonry work.

mortise - A slot cut into a board, plank, or timber, usually edgewise, to receive tenon of another board, plank, or timber to form a joint.

mullion - A vertical bar or divider in the frame between windows, doors or other openings.

muntin - A small member which divides the glass or openings of sash or doors.


nail inspection - An inspection made by a building inspector after the drywall material is hung with nails and screws, and before taping.

NEC, National Electric 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 carried electricity from an outlet back to the service panel. Also, see hot wire and ground.

newel post - The large starting post to which the end of a stair guard railing or balustrade is fastened.

NM - A type of Romex, non-metallic sheathed electrical cable that contains several conductors. The cable, which is flame-retardant, is limited to use in dry locations only, and cannot be exposed to excessive moisture.

NMC, Non-Metallic Conduit A type of Romex cable, non-metallic sheathed cable that contains several conductors. NMC may be used in damp or corrosive locations as well as dry areas.

non-bearing wall - A wall supporting no load other than its own weight.

nosing - The projecting edge of a molding or drip. Usually applied to the projecting molding on the edge of a stair tread.

notch - A crosswise groove at the end of a board.


OC, On Center - The measurement of spacing for studs, rafters, and joists in a building from the center of one member to the center of the next.

ohmmeter - In electrical contracting, a device to measure the resistance across a load. They are never used on a live circuit. Is is used to track down broken wires.

open hole inspection - When an engineer, or building inspector, inspects the open excavation and examines the earth to determine the type of foundation that should be installed in the hole, ie - caisson, footer, wall on ground, etc.

OSB, oriented strand board - A manufactured 4'x8' wood panel made out of 1" - 2" wood chips and glue, often used as a substitute for plywood.

outrigger - An extension of a rafter beyond the wall line. Usually a smaller member nailed to a larger rafter to form a cornice or roof overhang.

outside corner - The point at which two walls form an external angle, one you usually walk around.

overhang - Outward projecting eave-soffit area of a roof; the part of the roof that hangs out or over the outside wall. See also cornice.