Doors in a dwelling house.

[Tom Sutton]

What is the required fire resistance of doors in a domestic dwelling, I know they do not require self closers except if they have a door to a integral garage, but should they be FD30 doors with or without an intumescent strips or just standard robust doors and what about loft conversions? I know CP3 was clear but ADB is another matter.

[Fishy]

AD-B does cover this pretty well, I think (Diagrams 1-3)?  Assuming a simple, single-family dwelling with nothing clever about the layout, FD 20 / E20 where they are on a protected staircase (often needed for houses three-storeys and higher), FD 30 / E30 self-closing between the dwelling and a garage.

[Tom Sutton]

Thanks Fishy diagrams 1 & 2 with B1 told me what I need to know but as it appears FD20 door do not exist and you have to used FD30 doors so why ask for them?

From a little research I found the following.

The Building Regulations Approved Document B identifies minimum fire resistance periods for various elements of construction, including fire doors. The guidance recommends doors with a fire resistance period of 20 minutes (FD20) in some instances, and 30 minutes (FD30) in others.

In the distant past, it was possible to obtain a fire door that had a dual classification. Following a test, this door design could be accepted as an FD30 if installed with intumescent seals, and as an FD20 if installed without seals. In developing the BWF-CERTIFIRE Fire Door and Door Set Scheme in 1995, the BWF and the fire door manufacturers noted when testing dual rated doors that, in order to meet an FD20 rating without intumescent seals, the door had to be fitted very accurately into its frame, with little margin for error. This would be difficult to achieve consistently on site. Furthermore, this accurate fit would have to be maintained during the service life of the door assembly.

This reliability could only be achieved with doors fitted with intumescent seals; the safe practice is to have side and top edge seals in place for both FD20 and FD30 requirements. It was decided from the Scheme?s inception that its door manufacturing members would no longer test and sell an FD20 fire door except with intumescent seals fitted. Typically this determines that an FD30 product is in fact used for both levels of performance.

[Fishy]

There's nothing whatsoever to stop anyone making / testing / selling FD 20 doorsets... the British Woodworking Federation (BWF)members collectively decided some years ago that they weren't going to supply them (and published guidance stating this) & some third-party certification schemes followed suit.  That doesn't mean, though, that our building reg's guidance necessarily needs to be altered to reflect this decision by one part of the joinery industry.

Have a look at this document which suggests that doors sold as 'FD30' but not installed using intumescent strips are widely accepted by building control bodies as FD20 equivalent: https://www.labc.co.uk/sites/default/files/bca_guidance_note_9_fire_doors_in_dwellings.pdf

[Tom Sutton]

Thanks fishy that information leaflet was ideal.

[Auntie LIn]

Sorry to be so late in picking up on this chaps, but you're asking for trouble if you take an FD30 door, leave the fire seals out, and then 'deem' it to be FD20.   Even under BS476:  Part 22 you can't guarantee 20 minutes without seals however closely fitted the door is, so with the change in pressure regime in EN1634-1 I can't believe there'd be any chance for it to work.

[Fishy]

Sorry to be so late in picking up on this chaps, but you're asking for trouble if you take an FD30 door, leave the fire seals out, and then 'deem' it to be FD20.   Even under BS476:  Part 22 you can't guarantee 20 minutes without seals however closely fitted the door is, so with the change in pressure regime in EN1634-1 I can't believe there'd be any chance for it to work.

I'm sure you're correct, Lin - no-one is suggesting that all doors currently offered as FD30 with intumescent strips would do 20 minutes if they were fire resistance tested.  The point is, though, that (in my experience) Building Control invariably accept that FD30 doorsets without the intumescent strips are acceptably safe when installed where FD20 doorsets are recommended in dwellings - the BCA Guidance Note basically states that this 'custom and practice' is deemed acceptable.

[AnthonyB]

My cynical head would say that just because a BCO accepts it doesn't mean it's any good.....