How many ceiling-mounted smoke detectors are required when door release equipment is needed, if the header from the door to the ceiling is 28″ on both sides?

To determine the number of ceiling-mounted smoke detectors required when door release equipment is utilized, it is essential to consider the specific installation requirements outlined in the relevant codes, such as the National Fire Protection Association (NFPA) standards or local building codes.

When a door has a header height of 28 inches on both sides, this can create an area where smoke could accumulate before reaching the ceiling level. The code typically requires that smoke detectors be installed to ensure coverage in areas where smoke may not directly reach a single detector due to such obstructions. In this scenario, having door release equipment indicates a potential for a wider coverage area to ensure that the detection of smoke is reliable, as the presence of a door may limit airflow and smoke movement.

Therefore, two detectors are necessary. One detector should be positioned near each side of the door to provide adequate early warning in the event of a fire, particularly given the height of the door header. This dual coverage ensures that smoke from either side is detected promptly, aiding in the overall fire safety strategy of the building.

In summary, having two detectors is justified to ensure compliance with safety standards and effective smoke detection around the door with a 28-inch header.