Insulation is often touted as being the cheapest and best way to make your home more energy efficient – and for loft insulation that is probably the truth. However the story for cavity wall insulation is a little more complicated and it depends entirely on a number of important factors.

Most homes which are built after the 1920s have a space between the outer brick and the inner block which is usually left empty. This airflow is required to prevent dry rot and other problems associated with damp (although this doesn’t always work if water gets into the space). However it also means that there is a good chance that much of the heat in your home is being lost through your walls.

Due to improved heating in our homes these days and the use of air bricks, it is now possible to add insulation to this wall gap without causing problems with the airflow or causing damp in your home.

Wall cavity insulation is installed via a tube from your outer wall into the space. The insulation which could be beads, foam or wool is pumped in to fill the gap. Most homes will benefit to the tune of around £150 each year from wall cavity insulation alone and at a cost of around £500 to install, it makes it a worthwhile thing to do. But not all homes are going to benefit in this way and some may actually be harmed from the process.

 Which homes do not need wall cavity insulation?

If your home is older than 100 years there is a good chance that you do not have a gap in your exterior walls. Building methods tended to have thicker brick walls or single brick walls before this time. Similarly if your home has been built in the last ten years it is likely you already have wall cavity insulation of some sort installed. You can have this checked by an expert if you are not sure.


If your exterior walls are difficult to access you may not be able to get the equipment to the wall to carry out the work. This could be a problem if your walls are attached to a neighbouring property or it is built on a hillside or similar. However there are often ways around this.

 Do you already have damp?

Damp issues should always be sorted out before wall cavity insulation is installed. This is vitally important because insulation will affect airflow and could make the problem much worse. Water can also wick along the insulation, spreading the problem. Make sure your installer has checked carefully for damp before they start.

Wall cavity insulation is a great starting point for improving your home’s energy efficiency and if it is suitable for you, there are a number of scheme available which will make it cheaper. Just contact your council or look online for opportunities in your area.