Mar 31 2017

Fire Door Smoke Detectors

Q: I have a life safety consultant doing our annual inspection, and he keeps saying that I need to have individual smoke detectors for my corridor fire rated doors. The corridors on both sides of these doors are completely protected with smoke detectors, but he says regardless, that area smoke detectors are required next to the doors. Is this correct?

A: No, I don’t believe what the consultant is telling you is correct. Section 17.7.5.6.1 of NFPA 72 (2010) allows for either area smoke detectors or complete corridor smoke detector protection to activate the release of a hold-open on a door serving a fire barrier or a smoke compartment barrier. So, in regards to the cross-corridor doors that are held open by magnets connected to the fire alarm system, you are permitted to have one of the following:

  • A smoke detector on either side of the door mounted within five feet of the door; or smoke detectors mounted on both sides of the door within five feet if the transom above the door is greater than 24 inches.
  • The entire corridor where the cross-corridor door is located is properly protected with smoke detectors. A smoke detector must then be located within 15 feet of the door. For mounting locations for an area protected with detectors, the detectors must be no more than 15 feet from the wall (this is based on one-half of the maximum spacing distance between detectors which is 30 feet). The cross-corridor doors must be considered ‘closed’ when designing the detector locations, so that constitutes a “wall” and a detector is required within 15 feet of that wall.

Where consultants and surveyors have problems is they see a cross-corridor door held open by a magnet, and then they do not see a detector within five feet, and they believe that is a violation of NFPA 72. What they don’t consider is the corridor is completely protected with smoke detectors and NFPA 72 (2010) 17.6.3.1.1. (1) allows a detector to be one-half of the maximum spacing.