Fire Door Rebate dimensions

[Gordo]

Hello,

I'm looking for some advice regarding replacement of some doors after a burglary. The existing doors have a 25mm rebate but the replacement ones have got around 13mm rebate but I cannot find any information on specifically what size rebate is required.

The doors open onto a staircase, if that makes a difference and both openings are made up of 1 door and a bolted half leaf door.

Thanks for any assistance

[AnthonyB]

The inch rebate harks back to the days of fire doors before the introduction of intumescent strips and cold smoke seals and isn't usually needed on a door with such items fitted. Manufacturers instructions should be followed and it should be noted that a tested rated doorset includes the frame as well as the door so care needs to be taken with a new door in an existing frame.

The fire door specialists on here will give a more detailed response.

 

[Neil Ashdown MAFDI]

Hi Gordo,

From what you say it seems you have purchased new door leaves to replace existing ones damaged in a burglary and that these are to be fitted in the existing door frame. AnthonyB is correct, the usual rebate size for the meeting edges of fire doors is 13mm because they are fire-performance tested with that rebate size in the furnace to the BS 476 or BSEN 1634 test.

The door leaf (or door blank) manufacturer will have produced installation instructions based on evidence from that fire performance test. Assuming the doors are being used as fire doors it is important that they are installed in exact accordance (including use of the correct door frame, seals and door hardware) with the door manufacturers installation instructions. Any deviation from the manufacturers installation instructions may invalidate fire performance certification and jeopardise fire separation performance.   

[Tom Sutton]

The way I read it is Gordo has had the doors fitted and they have been replaced with fire door sets (Door and Frame) to BS 476 part 22 and consequently they have the 12mm rebates I assume with intumescent strips/cold smoke seals. He now is concerned why the rebates are only 12mm and not 24mm as was required by BS 476 part 8. (previous standard)

 

 

 

 

[Neil Ashdown MAFDI]

Could be, Tom. Either way the installer should install or perhaps should have installed in accordance with manufacturers installation instructions.

[Guest JDC]

Am I to understand that the requirement for an intumescent strip on top and side edges of a door set of a FD30 is negated by the provision of a 12mm door stop rebate (solid or planted) if it is tested to  BS476 BSEN 1634 ?

[AnthonyB]

Not unless tested and passed as a complete doorset of door and frame - it would be unusual if it could pass this way as the rebate only method went out with the Ark as they were proven to be completely useless! You see 25mm rebates on old legacy doors from before the existence of intumescent strips, but you wouldn't usually see it now - remember it has been in some guidance that to get the FD20 rating for internal dwelling doors you could use an FD30 doorset but not fit the strips, implying a reduction in performance.