Q: Can fire doors be glazed?

A: Not all fire rated doorsets can tolerate glazing and it is therefore essential to check the test evidence/assessment data for that door. If the door can accept glazing then it is of paramount importance that the exact details are followed, as apertures may need to be internally framed/lined with timber.

Q: Can intumescent strips be over-painted?

A: Most manufacturers of intumescent seals recommend that, ideally, intumescent strips should not be painted over. For further clarification contact the seal manufacturer for supporting evidence and advice.

Q: If the door does not fit, can it be resized?

A: Resizing a doorset is not something that should be done without first contacting the manufacturer. Most door designs rely on components being of a minimum size in order to perform in a fire. Lippings are particularly important on typical flush door leaves – removing 3 or 4mm can, in some instances, halve the depth of a lipping, which could have a detrimental effect on the fire performance.

Q: Can rising butt hinges be used as closers for fire doors?

A: Approved Document B cites rising butt hinges as acceptable for use on fire resisting doorsets, providing there is suitable test evidence available. To the best of our knowledge, there is no supporting fire test data for the use of rising butt hinges and this, coupled with their known limitations, leads us to recommend that such hinges are not used with fire resisting doorsets.

Q: Can an FD60 doorset be hung in a softwood frame?

A: In practice it is very difficult to pass a 60-minute fire test using a softwood frame, simply because it chars more quickly than most hardwoods. For this reason dense hardwoods are usually used, but softwood would be permissible if it were supported by appropriate test evidence.

Q: Can additional features such as letter plates or eye viewers be fitted to a fire-rated door?

A: Fitting a letter plate or eye viewer will breach a fire rated doorset and has the potential to allow a direct passage for hot gases and flames. It is therefore important that:

• there is test/assessment data for the fire rated doorset to tolerate the ironmongery;

• the ironmongery being fitted has been previously tested in a doorset of comparable construction.

Q: Can kick/push plates be fitted to the face of the fire door?

A: It is usually permitted to face-fix kick plates and push plates to a fire-resisting door. We permit facing the door with metal to a maximum of 30% of the leaf area, provided that the metal face is surface fixed and does not wrap around any leaf edge or interfere with any essential intumescent seal. Above the 30% limit of leaf surface area, or for any other condition, further test evidence must be generated. The reason for limiting the area of metal on a door is because, when heated in the fire, the metal will expand, while the wood will shrink, causing distortion. It can also act as a heat sink, thus accelerating char and erosion at localised areas.

Q: Traditionally an FD20 doorset comprised a 25mm doorstop, no intumescent and a 30-minute blank. Is this still acceptable?

A: Prior to 1972 the British Standards prescriptively defined how to construct a fire doorset and this included using 25mm doorstops. Since then the standards have been changed and the method of proving performance is by independent testing. For economic reasons, manufacturers generally test to achieve 30 minutes and sell the same product for 20-minute applications as well. Purchasers should satisfy themselves that acceptable evidence exists, rather than working to out-of-date prescriptive solutions.

Q: Does the inherent spread of flame classification have any bearing on the fire performance of a timber doorset?

A: Spread of flame and fire resistance are two quite separate performance characteristics. Fire doors must prove their fire resistance rather than spread of flame
performance.

Q: Can existing doorsets be upgraded?

A: There are numerous methods for upgrading existing doorsets to enhance their inherent fire resistance, although every upgrade is specific to each doorset, so may not necessarily be appropriate for another design. The only way of ensuring that the most appropriate method is chosen – and to have the enhanced integrity performance underwritten – is by commissioning a site survey by a qualified fire engineer.

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