A gypsum plaster with no aggregates or fillers added. Sometimes called unfibered gypsum.

National Board of Fire Underwriters, now merged into the American Insurance Assn.

National Conference of States on Building Codes and Standards, a nonprofit organization formed to increase interstate cooperation and coordinate intergovernmental reforms of building codes.

A steel or wood beam that is run through an opening in a bearing wall and used to support the wall and related loads as work on the foundation below the wall is performed.

A set of rules governing safe wiring methods. Local codes—which are backed by law—may differ from the NEC in some ways.

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.

National Bureau of Standards, a federal agency.

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

The plane through a member (at the geometric center of the section in symmetrical members) where the fibers are neither under tensile nor compressive stress.

A substance that can damage the central nervous system. https://healthymaterialslab.org/tool-guides/hml-resources

Refers to a structural part that does not carry a load.

The NAF standard for No Added Formaldehyde is currently the highest federal standard regulating formaldehyde emissions. NAF certifies that composite wood is free of resins made from urea formaldehyde or phenol formaldehyde, which have the potential to off-gas after installation and are known carcinogens. NAF certification originated with CARB, and has since been adopted by the EPA for the TSCA Title VI regulation. https://healthymaterialslab.org/tool-guides/hml-resources

National Forest Products Association.

NAUF certifies that products have no added urea formaldehyde. As of 2018, this certification is no longer recognized as an exemption to CARB or TSCA Title VI regulations. https://healthymaterialslab.org/tool-guides/hml-resources

National Fire Protection Assn., an international technical society that disseminates fire prevention, fighting and protection information. NFiPA technical standards include the National Electrical Code which is widely adopted.

A wall supporting no load other than its own weight.

A single number indicated by the amount of airborne sound energy absorbed into a material. The arithmetic average of sound absorption coefficients at 250, 500, 1000 and 2000 Hz.

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

A particular use of land or a structure which is in violation of the applicable zoning code. Generally, if the use was established prior to the code rule which it contravenes, it may continue to exist.

Term indicating that the full measurement is not used; usually slightly less than the full net measurement, as with 2" x 4" studs that have an actual size when dry of 1&1/2" x 3&1/2".