Fire door safety, and ensuring the latest standards/specifications are being met, has been a major talking point since the Grenfell Tower tragedy. Certain questions crop up time and again, not least around intumescent, an important material for ensuring fire safety, but one that is often misunderstood. Here at William Channon, we’re keen to make things as simple as possible. So what is intumescent and how can common errors be avoided?

Put simply, intumescent is a material that expands under exposure to intense heat. Used as a seal around fire doors, intumescent is designed to fill gaps, block the supply of oxygen and slow the rate of erosion/charring during a fire. The latest regulations stipulate that EVERY fire door assembly must be fitted with an intumescent seal. In addition, intumescent protection often (but not always) needs to be added to a fire door’s essential ironmongery, such as lockcases, hinges and concealed self-closing devices that are critical to the door’s operation. Need us to check YOUR fire doors and the protection required? Please contact us here.

These are the basics, but some common questions that we are asked about intumescent include:

Does adding intumescent to an existing door make it a fire door?

  • The answer here is no. To ensure compliance, a fire door must be a fully-tested construction, with all the appropriate fire test evidence. Retrofitting intumescent does not make a door a fire door and should be avoided at all costs.

Can intumescent be replaced with a different material?

  • The answer again is no. Using a different seal to that which has been tested can have serious consequences for a fire door’s performance. There are different activation temperatures and different pressures/degrees of expansion, and using a different material could compromise the test evidence for the fire door and performance in a fire situation.

How do I know what size/type intumescent to use?

  • The size/type of intumescent seal used for the fire test can be acquired from the door blank manufacturer or the test evidence/door data sheet. Fitting anything else will compromise the test evidence and the fire door’s performance – unless the substitution has been authorised by a qualified expert. Factors to be considered include the fire resistance required and the door type, but as with everything outlined here, we can advise/support.

How do I know what additional intumescent protection is required?

  • The essential ironmongery (including hinges and lockcases) often requires additional protection (using intumescent gaskets), but not in all cases. To find out what protection, if any, is required, check the fire test evidence with the door manufacturer and always ensure that additional protection is the same material/thickness of intumescent as that tested.

Will an intumescent fire seal provide smoke protection?

  • Large amounts of smoke can/will pass through perimeter door gaps, unless an additional smoke seal is installed.

Can fire/smoke seals be painted over?

  • Painting over an intumescent seal will not compromise performance in a fire situation. However, flexible smoke seals should not be painted as this will have an adverse effect on smoke containment. Smoke seals that have been painted over should be replaced immediately.

These are the basics when it comes to fire door safety/intumescent and we that hope addressing these points has proved useful.

Got further questions, concerned about the condition of your intumescent or like to learn more? Please get in touch. You can always contact us here.