Daniel Green

Hi Ant It's good to hear from you! And I see now that I was wrong on the door gaps for period doors. But the research has been useful for me, and I feel I have more "backup" when I am writing my recommendations on my FRAs. Thank you. I couldn't find BS 459 Part 3:1951, but I did find a really useful Fire Research Note no 855 from 1971 by W A Morris "An investigation into the fire resistance of timber doors" showing the critical importance of the 3mm (or less) gap in doors with 25mm rebates. Neil, thank you, too, for your advices Daniel

thanks Neil I hate to be argumentative, but BS 8214: 2016 relates to modern fire doors; indeed the note that you refer to under 9.5.2 (which is not a normative standard) has text underneath it which relates to intumescent strips and smoke seals. It's clear to me that this standard is not appropriate for assessing period fire doors, Darren Minton's article in the RICS journal is interesting for me; whilst it doesn't give specific guidance on door gaps, it does warn of the dangers of assessing old doors against modern standards. The conclusion I am coming to is that there are no standards for door gaps for period doors, and it's just left up to the fire risk assessors judgement...which doesn't really help me much, as a fire risk assessor! So given the lack of an independent standard, I am forced to think through the logic of the period door "technology", in that the critical element is that the door face needs to form a strong seal with the rebate. And on that basis, unless anyone can show me evidence otherwise, I plan to accept doors with bigger gaps.

Hi Neil I have reviewed BS 476 Part 8 of 1972 and I see that clause 7.1.2 reads: "the gap shall be at least 3 mm between door edges and the frame." So why can the door not have a 4mm gap, 5mm or 6mm? Moreover, I just don't see the logic of the door needing to have a particular gap, as long as the gap is not so big to 'miss' the rebate and that the door sits flush against the rebate. Daniel

I agree. The specific guidance you can use is the LGA "fire safety in purpose built blocks of flats". Although a bit old, it still hasn't been superseded.

The single most important thing you should do is to ensure that there is adequate early warning fire detection installed. As a minimum this should be installed on an LD2 basis (heat detector in the kitchen interconnected to smoke detectors in the corridor). The smoke detectors should be loud enough to wake sleeping occupants and you should test these on a monthly basis. If you are concerned that they are not loud enough or have other concerns, you could upgrade them to have LD1 coverage (interlinked detectors in all rooms). The other thing you should do is to ensure that your escape route from the furthest point in the house to the final escape door is kept clear at all times.

I am hoping someone can give some advice here, as I can't find any anywhere else! I am fully aware that gaps around modern fire doors should be 3mm (+/- 1mm) and this is because the intumescent strip and smoke seal are rated for gaps that size. However, I conduct a lot of fire risk assessments for residential blocks of flats built in the 1970s and 1980s where the CP3 standard applied, requiring 25mm rebates. The requirement for that standard was the door to be flush against the rebate, to prevent smoke and fire from getting past. In accordance with the LGA guidelines, and also BS 9794 (Clauses 9 and 10.4) I am happy to accept these doors in principle, including the two hinges, on the basis that they are fully self-closing. However, my questions is about the gaps around, and what are the tolerances permitted, but nobody seems to know about this. It seems to me, that the 3mm requirement should only apply to fire doors where there is a reliance on an intumescent strip and smoke seal, so what tolerance should I accept for these "notional" fire doors? Would say a 5mm gap be acceptable? Or maybe larger one, provided the door frame fits tightly against the rebate (ie up to 25mm)? Thanks in advance for any advice