Cavity Wall Insulation

About a third of all the heat lost in a home without insulation escapes through the walls. Generally speaking, houses built from the 1920’s onwards were built with cavity walls suitable for insulation.


If you have any damp patches on your internal walls then they should not be insulated until the problem is resolved. Speak to a builder who specialises in damp prevention.

To insulate your cavity walls, the installer drills small holes around 22mm in size at intervals of around 1m in the outside wall of your home. The installer then blows insulation into the cavity using special equipment. Once all the insulation is in, the installer fills the holes in the brickwork so you’ll barely notice them.

In most cases cavity wall insulation can be installed relatively cheaply and can pay back the amount spent in energy savings in as little as 3 years.

Filling cavity walls is not a job you can do yourself and you will need to employ a registered installer, who should be a member of one of these organisations:

Remember also to check whether the installer is signed up to a code of professional practice like the one provided by the NIA and that the installation is guaranteed for 25 years by CIGA.

Always look out for any grants on offer. The Energy Company Obligation provides funding from the larger energy suppliers to support energy improvements for people on certain benefits, for hard-to-treat properties and for households in the poorest parts of the country.

Additional Resources:

CSE      Cavity Wall Insulation Advice Leaflet;

EST      Cavity Wall Insulation.