NFPA 80 specifies fire-rated door requirements. Testing per ASTM E152 or UL 10B measures time to temperature rise and flame leakage. 20-minute doors are used in 1-hour barriers, 60-minute doors in 2-hour barriers. Frames must be fire-rated and properly installed. Hardware including hinges and closers must be fire-rated. Labels affixed to doors indicate rating. Installation must follow tested assembly design.