Can I make a bespoke fire door

[Guest Tims]

HI , we are a bespoke joinery company, who have been asked to ensure a door within a panelled wall is FD20 rated. Is it possible for us to make up a door to a known construction, or does it have to be tested? Alternatively, can we overlip and veneer a fire rated panel without altering it's rating?

[Tom Sutton]

First of all there is no such a thing as a FD20 fire door the lowest standard is FD30 fire door. I accept people still use the term but it was altered years ago.

There are two types of fire door a certified and a nominal fire door. A certified door set has documentation to prove the specification has been subjected to BS 476 part 22 and/or part 31.1 and the paperwork is a form of guarantee. A nominal fire door is one were an assessor is thinks the construction of the door should prevent the passage of fire for the stated period. You cannot have a certified fire door it must be a fire door set ( door and frame) therefore anything else is a nominal fire door.

It all depends on your customer and/or the enforcing authority to accept your assessment.

A solid door 44mm thick should provide the necessary fire resistance the weak points are the gaps, therefore the installation is very important. The gaps between the door and frame should not exceed 3mm and because a door is subject to warping in a fire the need for intumescent strips on each jamb and the top of the door or frame is essential. The door furniture is also very important especially the hinges usually three steel hinges are required and if the intumescent strips are rebated in to the door intumescent material must be fitted under the hinges. All fire doors should be fitted with self closers and if the door is required to control cold smoke you must fit cold smoke seals.

The testing of fire doors is not economical for a small run of doors and if you require a certified fire door set you should buy in. However your suggestion to veneer a fire rated door would most probably be acceptable because once the veneer has burned away you will still be left with the fire door. simples!

If you require a more in depth information check out Architectural and Specialists Door Manufacturers Association and download the Best Practice Guide to Timber Fire Doors. You can also try http://www.firesafe.org.uk/fire-doors/

[Guest kay]

we have solid oak doors they are 48mm thick 

we have been told that we have to change them by our building inspector for fd20 fire doors

i ahve done some research and found a varnish that would make them fire doors would they still have to be changed ?

[Neil ashdown]

It seems that its the building inspector that has to be satisfied, in this case.  Therefore submit the data sheet and fire performance evidence for the varnish product to the building inspector.

Alternatively contact  an independent certificated fire door inspector for help.