I work in a relatively new office buiding that has internal fire doors with cold smoke seals and the gaps under the doors range from 5mm to 10mm.
Maximum gap for fire door thresholds.
Under the bottom of a door.
In many cases the installation instructions require a maximum of 1 8 in.
That will be a problem according to section 8 3 3 1 of the 2012 life safety code you must install fire rated door assemblies in accordance with nfpa 80 2010.
1 8 for more detailed gap information refer to nfpa 80 section 6 3 1 7 and section.
1 8 meeting edges for a pair of doors.
If a door is to work effectively in its normal role the door leaf must be free to move within the frame and in order to achieve this there must be a gap around the perimeter.
Bs9999 2008 recommends for fire doors with cold smoke control that the threshold gap should be either less than 3mm in height or should be fitted with a threshold seal.
Thresholds and saddles like other fire door assembly compo nents thresholds and saddles need to be installed in accordance with their in stallation instructions.
Mind the gap fire door seals fire doors play a crucial role in restricting the spread of fire and smoke.
In general clearance for those allowed gaps are as follows.
3 4 between door and frame.
Nfpa 80 fire doors and other opening protectives.
It is through extensive testing of fire rated doorsets together with knowledge of the pressure regime within a fire test that a larger gap is permitted at the threshold of the door.
Current model codes call for some doors to have a maximum air leakage rate of 3 0 cubic feet per minute per square foot 0 015424 m3 s m2 of door opening at 0 10 inch 24 9 pa of water for both the ambient temperature test and the elevated temperature exposure test.
Clearance between the bottom of the door and the portion of the threshold directly under the door see.
If a frame bears a recognized label qualifying it as a fire door frame it may sup port a 3 hour a 1 1 2 hour a 3 4 hour or a 1 3 hour door.
What is the maximum you can have between the bottom of door and the thresholds for a fire rated door assembly i have some stairwell doors with 1 inch to 1 inch gap between the bottom of the door and the threshold.
There is negative pressure at the threshold during test conditions and so cool air is drawn in underneath the 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.
Bs9999 2008 recommends for fire doors with cold smoke control that the threshold gap should be either less than 3mm in height or should be fitted with a threshold seal.
