If you have a requirement for cold smoke control eg fd30s your threshold gap should be less than 3mm or you should fit a threshold smoke seal.
Internal fire door gaps.
I think it is too big and think a 1 4 1 2 gap would accommodate any unevenness in our floors and allow us to use area rugs.
According to the rules gaps are always calculated individually and depend on the geometric design parameters.
Around the edges of the door will be the intumescent seal which is designed to expand when temperatures reach beyond 200 c to seal the gaps between the door and frame.
In general the gap should not exceed 3 mm.
If this information is not available it seems reasonable to permit a gap of up to 8mm for general fire doors eg fd30.
The fire door gap gauge the fire door gap gauge is a must have tool for building inspectors iors fire marshals and ahjs for inspection of non rated and rated fire doors in warehouses office buildings hospitals and residential high rises.
For a private premises it is advised to install fire doors where the risk is most imminent for example the kitchen or rooms which house lots of electrical devices.
Ask your fire door manufacturer for their recommended threshold gap.
The gap between the door leaf and the frame must be suitable for the intumescent seal fitted.
Weight height and width of a door.
In this case the reasonable error is 1mm.
For fire doors it is 3mm 1mm for the gap each side and the top of the door also fitted with smoke seals if cold smoke control is required.
If according to their dimensions a door must have 5 mm gaps between a leaf and a frame considering a possible error they can be from 4 to 6 mm.
My contractor just hung our fancy dancy un painted solid wood door slabs in my 100 year old house with solid hardwood floors throughout.
Generally for gaps up to 15mm you should completely fill the gap to the full depth of the door frame with tightly packed mineral wool.
Excessive fire door gaps are a significant problem to alleviate for hospitals and healthcare facilities with the recent updates in code compliance from the centers for medicare medicaid services cms.
