Glossary

This glossary was designed to help those not directly involved in roofing with their understanding of roofing terminology. Many technical and chemical terms were not included.

NAHB: National Association of Home Builders

Nailer: A piece of lumber, preferably treated, that is secured to the deck, walls, or to premanufactured curbs. Nailers are used to receive fasteners for roof membranes. Generally, nailers are installed wherever it is necessary to secure base flashings and edge metal. Also see Blocking.

Nailing Pattern: Refers to a specific method or pattern at which nails are applied. For instance, a nailing pattern for base sheets on plywood roof decks can be "Nine and Eighteen". This means one row of nails on the outside edge of the sheet set at nine inches (9") on center, and two rows in the center of the sheet, each set at eighteen inches (18") on center.

Neoprene: A synthetic rubber produced by polymerization of Chloroprene for use in liquid-applied and sheet-applied elastomeric roofing.

Nesting: To overlay existing shingles with new shingles and butt the top edge of the new shingle up against the bottom edge of the existing shingles.

Net Free Vent Area: The area permitting unrestricted air flow.

Newton (N): In the meter-kilogram-second system, the unit of force required to accelerate a mass of one kilogram one meter per second per second (s².)

NICA: National Insulation Contractors Association

Night Seal: To temporarily seal the edge of a roof membrane in order to protect it from moisture entry. A.K.A. Night Tie-Off and Water Cut-Off.

Ninety-Pound: Granule-surfaced or fiber glass or organic felt roll roofing that has a mass of approximately 90 pounds per 100 square feet.

NIST: National Institute of Standards and Technology

Noble: In reference to metal, inert or inactive.

No-Cutout Shingle: A shingle made of one solid strip of material.

Non-Breathing Membrane: A membrane that does not permit water vapor or air to permeate it.

Non-Flammable: Material with no measurable flash point.

Non-Friable: Refers to a material’s inability to be crushed or pulverized into a powder.

Non-Volatile Content: The portion of a material that will not evaporate.

Non-Vulcanized Material: A material that retains its thermoplastic properties throughout its service life.

Nonwoven: Random arrangement of the reinforcement fibers of a scrim sheet or mat.

Nosing: Metal flashing bent at a 90º angle and is installed around roof perimeters, curbs, platforms, etc. in order to protect the edge of the roofing system. Nosing should not be used in place of drip edge. To see the difference in the two, click here.

NRCA: National Roofing Contractors Association.

NTRMA: National Tile Roofing Manufacturers Association