Fire doors may need to be trimmed down for a few different reasons.
You might be fitting a new fire door into an existing frame and the door needs to be trimmed to fit the existing space, or you may have opted for a standard size door and it needs to be reduced slightly to fit. However there are limits to what can be trimmed, and how much.
How much can I trim off a fire door?
Nothing should ever be trimmed off the top of a fire door, however the bottom and sides of a fire door may be trimmed depending on the door manufacturer’s guidelines and the test evidence provided.
The top of the door cannot be trimmed as the labelling and plug identifying the type of door can be lost in doing this and it’s essential to access this information easily throughout the lifetime of the door in order for it to be maintained correctly in line with the testing carried out on that type of door.
The bottom and sides of the door can be trimmed down, but this is dependent on what the door manufacturer states is in line with their testing.
Fire door gap allowances
It is essential that fire doors do not have excessive gaps between the door leaf and the frame as it can allow fire and smoke to pass through easily, breaching the compartment.
However, it’s also important that fire doors function properly and open and close smoothly during day to day use so there is some tolerance for gaps:
There should be a gap of 2-4mm along the top and vertical sides.
Along the bottom of the door there should be no more than a 10mm gap on a fire only door, or for fire and smoke resistant doors, this should be no more than 3mm.
Problems with trimming fire doors
The issue with trimming too much from a fire door is that the door core is often made from a less fire resistant material and so if a door is trimmed down too much it can leave the door core exposed, thus losing its integrity in the event of a fire a lot more quickly than is required.
Also, if a fire door is trimmed down by more than is allowed according to the door manufacturer and the test evidence, this then means the test certification is void as it has been altered outside of the scope of certification.
Conclusion
Whether fire doors can be trimmed always depends on the door manufacturer’s guidelines and test evidence. If a door is trimmed outside of the scope of the manufacturer the door’s certification is then void and may not work as needed in the event of a fire.
Read about how a fire door can be modified.
At FireSealsDirect we are experts in passive fire protection, stocking a vast range of fire door hardware from intumescent strips to drop down seals and door closers all from brands you can depend on.
For any advice on the maintenance and fitting of your fire doors get in touch with us today at [email protected] or 02920 857 959.
