Gaps of fire door

[Guest FLora Yao]

Dear all,

Could you tell me if there is a maximum gap between the unequal door leaves of double leaf fire door?

if there is a maximum gap size at the bottom of the fire door?

Thanks in advance

[Tom Sutton]

A fire door has two purposes, first to resist the passage of fire and hot gases including hot smoke and designated FD. The second is to resist the passage of cold smoke and is indicated FD followed by an s.

A FD fire door should be fitted with intumescent strips along the sides and top of the fire door/frame including the gap between the leaves of a double leaf fire door. The gap along the sides/top/between the leaves should be 3 mm +/- 1 mm and the old guidance stated the thresholds should not exceed 8/10 mm no mention of cold smoke seals, the new guidance states, BS 8214:2008 Under-door (threshold) gaps should be in accordance with the manufacturer’s installation instructions for the particular door-set design.

If the fire door is FDs it should be fitted with cold smoke seals (brush/rubber) sealing all the gaps including the threshold and the latest guidance states, BS 8214:2008. When fitted, smoke seals should give an even contact with the floor but should not exhibit significant increased frictional forces that could interfere with the closing action of the door.

[Guest StevenM]

Hi

What is the margin allowed to underside of 30-60min fire dooors to building control regulations?

Steven

[Tom Sutton]

As I say above,

BS 8214:2008 for FD and FDs the Under-door (threshold) gaps should be in accordance with the manufacturer’s installation instructions for the particular door-set design.

BS 8214:2008 says for FDs When fitted, smoke seals should give an even contact with the floor but should not exhibit significant increased frictional forces that could interfere with the closing action of the door.

So it depends if the fire door is only required to hold back a fire for the prescribe time (FD) or it also require to control the passage of cold smoke (FDs) no measurements are stipulated, that is up to the manufacturer.

[Guest Mikefee]

Hi.

've recntly started the role of Health & Saftey governor at my local school. Some of our fire doors have gaps of between 5 amd 15 mm in places, which I think is excessive. Also, are fire doors designed to stop smoke spreading or just flames?

Basically, many double sets of doors have ill-fitting doors (e.g almost touching at the top but about 10 mm at the bottom). One set actually has been damaged and where they meet in the middle there is a gap of about 300mm high and 40 mm wide to the bottom of the door.
Sorry if these questions souns naive!!
Thanks in advance
Mick

[Tom Sutton]

First you need to establish the fire strategy including the means of escape scheme and decide which doors are fire resisting doors. There are FD doors which are fire doors with an intumescent strip, designed to prevent flames from spreading. Also FDs doors which are fire doors with an intumescent strip and cold smoke seal, designed to prevent flames/smoke from spreading.

All doors should have gaps not exceeding 3 mm +/- 1 mm especially fire resisting doors and any gaps greater than 4 mm could render a fire resisting door useless because the intumescent seal/ cold smoke seal may not function properly.

Check out http://www.firesafe.org.uk/fire-doors/

[Guest GulReha]

Hi,

I have installed a fire door in the property. Unfortunately, there is a gap below the fire door and i have been advised by the council to fit a fire resistant material in order to close the gap. The gap is approx 15mm-20mm.
Can you advise what fire resistant material i can attach to the fire below to cover the gap?
Best Regards
Gul

[Tom Sutton]

You could just use a piece of solid hardwood or you can get threshold smoke seal. Check out http://www.ifsa.org.uk/pdf/Information%20Sheet%205.pdf.

[Safelincs]

hi Gul

Certainly gaps up to 14mm can be dealt with through threshold smoke seals

Harry

[Guest H]

Hi, Is there a way to reduce the gaps between fire door leaves and the frame on the sides and top. It is supposed to be max. 4mm and I have a gap of 6mm. Could you advise please.

Thanks,

H

[Tom Sutton]

Check out http://www.envirograf.com/category/carpenters_and_builders/11.replacement_hardwood_door_edging.html or contact envirograp and see if they can help.

[Guest GrantAm]

I have a 6 bedroom student property in Guildford. Is it acceptable to have a 1cm gap between the bottom of the door and the floor? I need the gap to increase ventilation and air flow within the property.

[Tom Sutton]

I would say 1 cm gap is acceptable but as you require FD30s fire doors, you need intumescent seals to sides and top of door. You will also require cold smoke seals to all the sides of the door which includes the threshold and this will defeat your attempt to increase the ventilation.

This is based on a FAQ from TRADA:

The recommended leaf edge to frame gap specified in BS 8214: 1990 is 4mm on all edges. Intumescent seals are engineered to react within this size of gap to give optimum sealing and clamping performance.

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. There is negative pressure at the threshold during test conditions and so cool air is drawn in underneath the door. It is for this reason that there is unlikely to be a failure at the threshold and also why there is no need to fit a perimeter intumescent strip at this location (doorsets below FD60 performance). A larger gap at the threshold is also useful from a practical end use application for accommodating floor coverings. We recommend a gap of 10 mm from the bottom of the leaf to the structural surround.

[Tom Sutton]

Grant is your house classed as a shared house (does all the students have access to all of the house including the bedrooms) because this will affect my submission above? If it is a shared house then you will only require FD30 doors not FD30s doors and therefore will not require smoke seals. Check out HOUSING – FIRE SAFETY Guidance on fire safety provisions for certain types of existing housing for more information.

[Guest Shawn]

Hi Tom

Our fire doors have fairly large gaps on the side (10mm). Are we allowed to fit hardwood strips to the side to reduce the gap?

Thanks

Shawn

[Tom Sutton]

I cannot see why not most doors including fire doors have 10mm lippings to both sides and top of door, made of hardwood. You must also refix any intumescent strips and smoke seals if needed.

[Guest Steve Fensome]

Hi Tom,

I have a site that has 12 doors of which have a threshold gap of between 15-30mm. The doors are communal doors in blocks of flats.

Would it be ok to fit strips of hardwood the bottom of these doors to reduce these gaps?

Is there any special fixing/glue i have to use an do they have to be treated in any special intumescent paint?

Many thanks

[Tom Sutton]

It depends if they are FD30/60s fire doors you will require smoke seals as well as intumescent strips and on the threshold you should fix threshold smoke seals, check out link below. If they are FD30/60 fire doors then you need intumescent strips on the head and both sides, with a gap at the threshold of 6 mm or less. I cannot see why you shouldn't fit strips of hardwood the bottom of these doors to reduce these gaps, using urea formaldehyde or polyurethane adhesive but you should confirm this with the local Fire and Rescue Service.

http://www.safelincs.co.uk/search.php?q=threshold+smoke+seals&a=products

[Guest JOhn]

HI,

I have a double door which has lock but only one door opens. There is a gap of1cm where the doors meet. you can fit a pound coin sideways through the gap. one door has a brush seal and the other the flush expanding seal. is there anything else I can do to make this fire safe?

[Tom Sutton]

If the door is a fire door then it is not fit for purpose, it needs fixing, and the gap should not exceed 3 mm +/- 1 mm. The brush and intumescent seals will not work with just an excessive gap.

[Guest DaveW]

I've had two fire doors fitted, fitter gone AWOL, but one has up to a 6mm gap on one side. Intumescent seals are in the door.

Anything I can do to avoid new frame or new door?

Help

[Guest Neil Ashdown]

Hi Dave,

Its always best to make sure that anybody fitting fire doors can demonstrate their competence. Can't be definitive in my answer without seeing the door but it may be possible to remove the existing hardwood lippings (assuming it has them) and fit thicker ones to reduce the perimeter gaps to 3mm. By the way the threshold gap should be 8 to 10mm maximum (generally, may vary according to door manufacturer) for a fire door and 3mm for a smoke door or if 3mm can't be achieved you could fit a threshold seal to the door or a threshold strip to the floor.

Of course you will have to put a groove in the new hardwood lippings to accept the intumescent seals.

Cheers,

Neil Ashdown

[Tom Sutton]

You could have the door rehung and see if you can achieve less than 4mm on both jambs and head of door, this would mean the width of the door would need to be no less then 8mm of the frame opening. You maybe able to have the door modified so one of the lippings is increased in size or I am afraid its a new door or frame.

[brianpj]

I am fitting firedoors in a 3 storey conversion, not a HMO, but an ordinary domestic dwelling. I have a problem. I am installing the door linings, and allowing for a 3mm gap at the top, 8mm gap at the bottom, and a1981mm tall door. Now the questionable bit. I have been to my carpet provider, and have measured the thickness of carpet plus underlay to be 20mm. This carpet, with time will eventually flatten down, leaving the gap at the bottom potentially bigger than the 10mm maximum that Jeldwen require. What do i do to allow for this? i have thought of installing hardwood door strips, which obviously give a permanant fitting? Please can anyone out there help me?

[Tom Sutton]

You say the thickness of carpet plus underlay to be 20mm so if you leave a threshold gap of 20 mm, between the true floor and bottom of the door, when the carpet is fitted there will be no gap as the pile will touch the base of the door and as the carpet, with time will eventually flatten down, only a small gap should appear.