NOISE REDUCTION COEFFICIENT (NRC)
NEOPRENE RUBBER: A synthetic rubber having physical properties closely resembling those of natural rubber. Made by polymerization of chloroprenes.
NFPA: National Fire Protection Association. The NFPA promotes safety from fire and other hazards through the promulgation of codes, standards, research, training and education.
NIGHT SEAL: A material and/or method used to temporarily seal a membrane edge during construction to protect the roofing assembly in place from water penetration. May be removed when the roofing application is resumed.
NOISE REDUCTION COEFFICIENT (NRC): A representation of the amount of sound energy absorbed upon striking a particular surface. An NRC of 0 indicates perfect reflection (strong echo), and an NRC of 1 indicates perfect absorption (lack of echo).
NON-BREATHING MEMBRANE: A membrane material that has a significantly greater resistance to the diffusion of water vapor than the other materials with which it is used.
NON-FERROUS METAL: All metals that are not iron compounds (i.e., copper, lead, gold, silver, and aluminum). These metals are non-magnetic.
NON-FLAMMABLE: Not easily ignited and will not burn rapidly if ignited. The material may still burn and be considered combustible. OSHA defines a flammable liquid as any liquid having a flashpoint below 100°F (37.8°C).
NON-OXIDIZING: A material that resists oxidation in exterior exposures or accelerated weathering.
NON-VOLATILE CONTENT: That portion of a coating material that does not evaporate under normal ambient conditions. Compare with SOLIDS CONTENT. (See SOLIDS CONTENT.)NRCA: National Roofing Contractors Association.