Nailer: A piece of lumber secured to non-nailable decks and walls by bolts or other means, which provides a suitable backing onto which roof components may be mechanically fastened.

Natural Finish: A transparent finish which does not seriously alter the original color or grain of the natural wood. Natural finishes are usually provided by sealers, oils, varnishes, water-repellent preservatives, and other similar materials.

Neat Plaster: A base coat plaster which does not contain aggregates and is used where the addition of aggregates on the job is desired.

NEC (National 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.

Neoprene: A synthetic rubber having physical properties closely resembling those of natural rubber. It is made by polymerizing chloroprenes, which are produced from acetylene and hydrogen chloride.

Nesting: A method of re-roofing with new asphalt shingles over old shingles in which the top edge of the new shingles is butted against the bottom edge of the existing shingle tab.

Neutral Wire: Usually color-coded white, the neutral wire carries electricity from an outlet back to the service panel. Also see Hot Wire and Ground.

Newel: A post to which the end of a stair railing or balustrade is fastened. Also, any post to which a railing or balustrade is fastened.

Nipple: A short pipe installed between fittings. A pipe coupling that is threaded on both ends.

NM: A type of Romex cable (nonmetallic sheathed cable that contains several conductors). The cable, which is flame-retardant, is limited to use in dry locations only and can not be exposed to excessive moisture.

NMC (Non Metallic Conduit): A type of Romex cable (nonmetallic sheathed cable that contains several conductors). NMC may be used in damp or corrosive locations as well as dry areas.

No-Cutout Shingles: Shingles consisting of a single, solid tab with no cutouts.

Nominal Size: Size used for identification only; not literal dimensions.

Non-Bearing Wall: A wall supporting no load other than its own weight.

Non-Destructive: A phrase describing a method of examining the interior of a component whereby no damage is done to the component itself.

Non-Drying (Non-Curing): A sealant that does not set up or cure. See Butyl.

Non-fibered Aluminum Roof Coating: Thin but efficient reflective barrier to reflect sun's harmful rays and prolong surface life. Also works on metal surfaces.

Non-Sag: A sealant formulation having a consistency that will permit application in vertical joints without appreciable sagging or slumping. This performance characteristic allows the sealant to be installed in a sloped or vertical joint application without appreciable sagging or slumping.

Non-Skinning: Descriptive of a product that does not form a surface skin.

Non-Staining: Characteristic of a compound that will not stain a surface.

Non-Veneer Panel: Any wood-based panel that does not contain veneer and carries an APA span rating, such as wafer board or oriented strand board.

Nonfibered Roof and Foundation Coating: Dual purposed, this thin-viscosity material doubles as a nonfibered roof or foundation coating.

Normal Slope Application: Method of installing asphalt shingles on roof slopes between 4 inches and 21 inches per foot.

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 rabbet at the end of a board.

Note: A formal document showing the existence of a debt and stating the terms of repayment.

Nozzle: The tubular tip of a caulking gun through which the compound is extruded.

Nuclear Meter: A device used to detect moisture by measuring slowed, deflected neutrons.