How much can I cut of a fire door?

[Neil ashdown]

Hi Paul,

Yes this forum is very useful, I agree. The standard door size is 1981mm high so unfortunately you will be unable to cut a standard door as doing so would void its fire performance certification. However you will be able to purchase a fire door made-to-size. To clarify threshold gaps (under-cut) for fire doors: If the door also provides protection to limit the spread of cold smoke then the maximum gap is 3mm (or you can fit a threshold brush seal to contact the floor when the door is closed to a door with a gap of up to 10mm). If the door is fire only then the maximum gap is up to 10mm (depending on the door manufacturer's fire performance test evidence). Reference documents are BS 8214:2008 and BS9999 as well as the door manufacturer's installation instructions.

All the best,

Neil Ashdown CertFDI

FDIS fire door inspector

 

[Guest Dom]

Tom,

Sorry if you have already answered this (I am sure you have) but I wanted to get an answer directly.

We have a toilet core (consisting of two toilets) leading onto a lobby which leads to the main stairway. The door from this toilet area to the lobby is a FD30S. Air is being extracted from each toilet and supplied to the lobby. There need to be air flow between the two. We need to undercut the door by 25mm to allow sufficient flow. This assuming there are no gaps on all other side. Would this be too big a gap?

If so what is the maximum permissible gap in your opinion? We can get away with 15mm if we have 1.5mm gap down each side and at the top? Will this be allowed?

Thanks

[Tom Sutton]

You say it is a FD30s fire doors which would means you are limited to a threshold gap of 2/4mm any increased gap you would require to fit a smoke seal. Why do you require the toilet door to be FD30s is there a fire risk in any of the toilets? What standard is the door from the toilet lobby to the staircase? 

[AnthonyB]

A fire door may have been fitted, but it doesn't need to be.

[Guest MartinDix]

Is it legal to cut down and rebate solid core fire doors and if so. can you give me a idea of what we need as in edges, glue etc.

[Tom Sutton]

The fire resistance of a fire door could be affected unless you know the precise construction of the fire door, therefore any alteration could affect the fire door and reduce the fire resistance. I would suggest you do not alter the fire door or get an expert in fire doors to assist you. Check out http://fdis.co.uk/

[Guest hazza]

I have 11 FD30 doors I need and want to keep them the same style however have a few varying sizes which complicates matters.

Some could be trimmed by a few mm to get to the correct size and not lose integrity which is fine.

The problem is some need extending (as otherwise, the reduction needed if I got the next size up would be too much to keep the FD30 rating).  - is it possible to widen fire doors and still maintain the FD30?  As an example, the door needs to be 838mm wide and the nearest available size is only 826mm wide.

Thanks

Chris

[Tom Sutton]

Without knowing the construction you cannot give definitive advice but when you purchase fire door blanks you should receive a Global Fire Resistance Assessment which explains how to construct a fire door set like http://www.mbmfp.co.uk/downloads/FlamebreakFD30RevL.pdf. In your case you should check out and consider the lippings as explained in this document.

[Carla]

Hello, I have an internal fire door in my flat to my bedroom that I want to rip down the middle to make 2 doors, hinged on both sides. I presume this will compromise it's fire safety integrity. Is there any way that I can do this and still ensure the fire safety integrity of the door? I have a problem with the door taking up too much room and 2 narrower doors would give more room. Thank you

[Tom Sutton]

You could remove the existing door and replace it with two bespoke fire doors or consider a FD30 sliding door.

[Guest GazMart]

Hi,

I'm looking to switch standard doors to firedoors in an old house for HMO. We measured 2 doors to 29 1/2 inches...do I buy 2 30" doors and trim up either side ?

Many thanks for providing such an informative forum.

BR 

Gary.

[Safelincs]

Hi GazMart

As fire doors have to be fitted with very small tolerances (gaps have to be 2-4mm on top and sides) working in half inches makes it difficult to answer your question. Anyway, the amount that can be trimmed on modern fire doors is sadly very limited, as the lipping (the wood strip fitted around the door) is an essential part of the fire door during fire testing. Each door set type that a manufacturer produces and has tested, has gradually some of the lipping trimmed during repeated fire tests til the fire door eventually fails. This determines how much lipping can be trimmed safely. So, each fire door comes with a different permitted maximum amount of lipping removal and it is only small amounts that can be trimmed these days without risking invalidating a fire door.

Where does this leave you? Assuming that the frame is of sufficient fire resistance in itself, you need to measure the opening of the frame, deduct 3mm on each side which gives you the door leave you want and order that size of fire door. This can be done easily online. Fire door retailers are set up to deal with made-to-measure fire doors, which are then ready to be hung with minimal trimming.

Harry

[Guest Patrick]

We were advised that we needed to remove our old glazed doors when we had our loft converted. We bought glazed fire doors for the toughened glass but the builder has also put smoke detectors in all habitable rooms. The carpenter would like to remove more than the recommended 3mm to resize the doors. We don't actually need fire doors because of the smoke detectors. Any advice? Can the doors be trimmed more than 3mm just so the doors can be fitted? 

[Tom Sutton]

Smoke detectors in all habitable rooms will not stop a fire spreading so you may still require fire doors. As to the amount you can trim off a fire door will depend on the construction and the thickness of the lippings so you will need to contact the retailer or manufacturer to establish the amount that it is safe to remove, it could be 6mm or more.

[Guest geeze34]

I need to replace a fire door which is 1980 by 720 , if i purchase a 1981 by 686 can i plant a 34mm hardwood strip to side to bring up to size without effecting the fire rating on the door?

[Tom Sutton]

I am afraid what you are suggesting, would affect the fire rating, a certificated fire door would become a nominal fire door and if it has to satisfy an enforcing officer it may not be accepted. But you could consider a bespoke fire door, check out https://www.safelincs.co.uk/custom-30-and-60-minute-fire-doors-fd30-fd60/ for example.

[Guest Kay]

I am a new tenant and I have a one inch gap (not straight) under the external front fire door. Can the landlord cut more from the bottom to make it level and then fix a longer piece of wood on? 

[Tom Sutton]

Is the door square with the stile and it is the floor that is sloping or the reverse.

[Neil Ashdown MAFDI]

You can add a hardwood lipping to the bottom edge of the door. But if the floor is not level the hardwood lipping my need to be 'planed-in' to suit, also the door may bind on the floor due to uneven floor levels.

I would start by checking floor levels and would first consider fitting a threshold strip to the floor and then deal with any remaining issues with the door leaf bottom edge. 

[Guest Lesley Sutheran]

What is the max you can cut off the top and bottom of fire door

Our gap is 1923 and the door come at 1981

[Neil ashdown]

Most standard fire doors cannot be trimmed by such an amount and quite often the top edge may not be trimmed at all.  Contact a reputable fire door supplier and ask them for a suitable fire door.

[Guest Lee]

Hi, my joiner has cu the top of fire doors he has installed as the frames weren't even due to the house being old. The building inspector has now indicated that the FD30 stickers aren't visible and won't pass the door. My builder has advised that if we fit a 15mm intumescent strip to the top of each door this will help and I've gone back to ask the Building Inspector if this will be sufficient. Does anyone have any experience of doing this and also if it will meet the required standards? I'm not sure what else we can do given the age of the house. 

Fire doors were required as we had a loft extension completed and had to change all of the internal doors

[Neil ashdown]

There are two options here, the problem being that many timber-based fire doors have an integral top rail that should not be over-trimmed:

1) Always replace existing door frames rather than fitting a new door leaf only. This is most often necessary to achieve compliant installation.

2) If you must retain the existing door frame, then the door leaf must be custom made to suit the door frame. 

Furthermore, if you must retain the existing door frame ensure the following:

A) The framing material is in good condition and of suitable dimensions and density. 

B) The existing hardware (hinges/locks) positions are suitable for the new door leaf.  Any redundant cut-outs to the door frame must be competently repaired. 

C) The size and sealing of gap between the door frame and the surrounding wall meets the requirements of BS 8214.

[Guest JohnR]

I work in a 5 year old Care Home. An inspection has found that over 50 fire doors have excessive gaps and cannot be adjusted any more. Is it acceptable to engage a Company to add approximately 3 mm hardwood lips?

[Neil ashdown]

The lipping should be hardwood at least 640 kg/m3, at least 6mm retained thickness (after planing-in) and must not be in addition to existing lipping.  Adhesive should be urea formaldehyde.   Use a carpenter that has sufficient knowledge about timber-based fire door installation, maintenance and repairs.