Acceptable Gap Under Fire Door

When speaking with manufacturers however a common statement is that a fire doors gap of up to 8 mm underneath the door is permissible.

Acceptable gap under fire door. Nfpa 80 fire doors and other opening protectives. This is probably just referring to normal fd30 applications as the fire door manufacturer is not involved in upgrading fire doors to cold seal protected standard fd30 s. The gap between the door leaf and the frame must be suitable for the intumescent seal fitted. 1 8 for more detailed gap information refer to nfpa 80 section 6 3 1 7 and section.

To facilitate the checking of this gap on site the bwf certifire fire door and doorset scheme has produced a gap tester which can be used for this purpose. In general the gap should not exceed 3mm along the 2 long edges and across top of the door leaf to facilitate checking of the gap on site a bwf fire door alliance scheme gap tester is available on request here. 3 4 between door and frame. Contains information on maximum gap allowances for different types of fire doors.

It should be noted that when a 762 2 6 door leaf which is hung on standard hinges swings open the diagonal measurement of the leaf becomes effective and will reduce the clearance on the lock side by between 1 and 1 5 mm depending on the width and thickness of the door leaf. When a 1 8 in thick tool fits into the gap with no lateral movement the gap is within nfpa 80 s specifications. In general the gap should not exceed 3 mm. Check the door manufacturer s instructions.

Under the bottom of a door. For general fire doors eg fd30 it s generally accepted that a threshold gap of up to 8mm is acceptable but i would contact the door manufacturer to to see what their recommended threshold gap is for that particular design of door. For example the maximum door gap dimension for 3 4 hour and greater rated wood fire doors is 1 8 in no over tolerance dimension is permitted.