How to Install Intumescent Strips

27/08/2025

As suppliers of passive fire protection, we often fall into the trap of assuming that everyone knows as much as we do about intumescent strips. Obviously, this is not the case, so in this post, we would like to discuss some of the basics of intumescent strips, including installing them properly.

What are intumescent strips?

Intumescent strips are placed around the edges of doors and windows. These strips expand when exposed to a high heat – such as in the event of a fire. By expanding they block the gap that surrounds doors and windows, which in turn slows the passage of fire and smoke. They can come in various ratings, but the most common are 30 and 60 minute. This means that they can provide either 30 or 60 minutes of protection before ‘failing’.

This 30 or 60 minutes is vital time that could save a person’s life, whether they are trying to escape or waiting for the emergency services to arrive.

How to fit intumescent strips

The manufacturers of intumescent strips know of their importance. Therefore, they want them to be as easy to install and use as possible. Most good quality fire doors will have a pre-machined groove in which the strip will be placed. However, if your door does not have this groove then you will likely need to create one yourself using a router with a bit that is the same width as the strip.

Actually fitting intumescent strips is a relatively simple process – whether you have created the groove yourself, or your door already had one, simply clean it out so it has to dust or debris stuck in there, peel the back off the strip and stick it into the groove.

The door should close by itself with the aid of a door closer, however make sure you test it after the strip has been installed and, if needed, adjust the closer to make sure the door fully closes to ensure proper function and complete fire safety.

As well as intumescent strips, Noberne Seals provides a range of passive fire protection. To find out more about our range simply contact us.