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Posted By Anders Molko
What is the maximum gap allowed under a fire door? (Gap between door and floor)
Thanks
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Posted By Mitch
You will have to check with the manufacturer (s test certificate)
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Posted By Anders Molko
Thanks. WIll look into it.
The BS says 4mm though... with a max permitted gap of 5mm
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Posted By shaun mckeever
The maximum gap under fire doors is normally 8mm, however becuase of another building regulation issue which requires 10mm then 10mm is generally accepted.
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Posted By Anders Molko
Were does it say 10mm though?
Ive searched through legislation etc and the only thing i can find is 4mm in the Britsh Standards
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Posted By shaun mckeever
Anders
I don't recall the 'other' building reg requirement for 10mm because it is not fire related, I suspect it is something to do with ventilation requirements. If you are wondering where the 8mm bit comes from then I can tell you that. It is in 'BS 8214:1990 Fire door assemblies with non-metallic leaves' section 19.7. I have given this advice without confirming if the building is a pressurised building or not. This makes a difference because you will need to maintain a threshold seal if it is a pressurised building.
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Posted By Peter Taylor14
Im in anorack hell!!!!
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Posted By CFT
I believe the 10mm gap is restricted for the threshold and is a suggestion; 4mm remains for header and sides. I thought 8mm max for the bottom was more acceptable though
If you are in real doubt then the inclusion of a threshold to minimise the gap will help greatly, sloping away so as not to become a TH.
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Posted By shaun mckeever
Peter
sorry it seems like 'anorak hell' but in fact it is critical to the success or failure of the fire stratgey in a pressurised building. It is one of those issues that non-specialist fire risk assessors miss. It is why I have expressed my concerns in the past regarding the undertaking of fra's.
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Posted By Peter Leese
Hi Shaun, I'm not a layman with fire assessments but I'm not an expert either but...... I'd like to ask a question that's been puzzling me for a while.
If it can be certain anybody and everybody can get out of building within, let's say, 5 minutes (eg well practiced procedures), there are no dead ends, and that ample detector systems are in place that will raise the alarm almost immediately (and all fire equipment is regularly checked) - then does it matter about minor mm gaps whether or not the building is pressurised or such like things?
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Posted By Crim
Hi Guys and gals,
BS 4787-1 has lots of info re the above, and mentions nominal 3mm under door clearance.
The gap will depend upon the floor finish and can only be guaranteed when a four sided frame is installed.
BS 476 pt 20 fire test conditions states that the clearance gap at the bottom is less critical up to 10mm for fire performance reasons and gaps up to 10mm are being permitted, I think this is only during testing?
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Posted By shaun mckeever
Peter
Often the stairs are pressurised for the protection of firefighters. If, like me, you have experienced partial collapse of a building (I had to be pulled out by my feet by my colleagues) then as a firefighter you will appreciate the protection that is built into the the building at design stage.
Pressurised systems are also there for the protection of the occupants of the building. The pressure built up in a room on fire is enough to force the products of combustion into the protected stairs. The design of a pressurised system takes into careful consideration the leakage paths and the calculations are based on the leakage paths available. Increasing the leakage paths i.e. increasing the gaps under the doors, may have the effect of reducing the pressure in the stairwell to the point where the products of combustion enter the stairwell. Occupants faced with a stairwell full of smoke or combustion gases e.g. carbon monoxide may find that the route is not available for use.
So the design of the pressurisation system can be critical to the fire strategy of the building.
In answer to your question, yes mm can make a difference.
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Posted By Peter Leese
Thanks Shaun.
That now begs the question, do all fire risk assessments have to take into account emergency services personnel who may go into a burning building?
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Posted By shaun mckeever
Yes to the extent that section 38 of the RRO applies.
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Posted By Peter Leese
Maintenance of measures provided for protection of fire-fighters
38. —(1) Where necessary in order to safeguard the safety of fire-fighters in the event of a fire, the responsible person must ensure that the premises and any facilities, equipment and devices provided in respect of the premises for the use by or protection of fire-fighters under this Order or under any other enactment, including any enactment repealed or revoked by this Order, are subject to a suitable system of maintenance and are maintained in an efficient state, in efficient working order and in good repair.
(2) Where the premises form part of a building, the responsible person may make arrangements with the occupier of any premises forming part of the building for the purpose of ensuring that the requirements of paragraph (1) are met.
(3) Paragraph (2) applies even if the other premises are not premises to which this Order applies.
(4) The occupier of the other premises must co-operate with the responsible person for the purposes of paragraph (2).
(5) Where the occupier of the other premises is not also the owner of those premises, the reference to the occupier in paragraphs (2) and (4) are to be taken to be references to both the occupier and the owner.
Question: Could someone have a go at explaining how this translates in 'practical terms' to a fire risk assessment?
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Posted By shaun mckeever
I'll try Peter
Anything for the protection of firefighters must be properly maintained such pressurisation systems discussed above or dry rising mains or fire doors etc. All of these must be in efficient working order so that firefighters are not placed in danger.
Occasionally some systems might pass through other areas, for example extract ducting from commercial kitchens passing through service ducts in the office accommodation above. This ducting will need to be examined. Occupiers of the offices must permit access to allow maintenance to be carried out.
Occasionally some systems might pass through areas not covered by the RRO such as sub-surface railway stations. Access must be allowed for maintenance purposes.
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