How do I know if I have cavity wall insulation?

What is cavity wall insulation?

Cavity wall insulation is a type of energy-saving measure used in many British homes. It involves filling the gap (or ‘cavity’) between the inner and outer walls of your home with insulating material. This helps to keep heat in during the winter and out during the summer, reducing your energy bills and making your home more comfortable all year round.

Does your home have cavity walls?

Not every property has cavity walls, so the first thing to check is what type of walls your home has. If your home was built after the 1920s and before the 1990s, there’s a good chance it has cavity walls.

Here are some simple ways to tell:

• Brick pattern: If the bricks on your outside walls are all laid lengthways in a regular pattern, your home likely has cavity walls. Solid walls often show a mix of brick ends and lengths.
• Wall thickness: Measure an external wall by a window or door. Cavity walls are usually over 260mm thick. Solid walls tend to be thinner, around 220mm or less.
• Age of your home: Homes built before 1920 usually have solid walls. Those built between the 1930s and 1990s often have cavity walls. Since the 1990s, most homes have cavity wall insulation installed as standard.

How to check if your cavity walls are insulated

Even if your home has cavity walls, they may not be insulated. Here are a few ways to check:

• Drill holes or inspection ports: A qualified installer can drill a small hole in the wall to look inside with a borescope. This is the most reliable method.
• Check your paperwork: If your home has been insulated before, you may have a certificate from an installer or from a government-backed scheme.
• Cold spots and high bills: If you notice cold patches on your walls in winter, or your energy bills are unusually high, it could be a sign that your walls are not insulated.
• Ask a professional: If you’re unsure, a quick survey from a qualified energy assessor can confirm whether or not your cavity walls are insulated.

Can I get help with installing or upgrading insulation?

Yes, and this is where government-backed schemes like GBIS and ECO 4 come in. Both are designed to help households across the UK reduce their energy usage and lower their bills by funding things like insulation, heating upgrades, and more.

• The Great British Insulation Scheme is ideal for households that may not qualify for full ECO funding but still want to make improvements.
• The ECO 4 scheme supports low-income and vulnerable households with more extensive energy efficiency upgrades, including cavity wall insulation, loft insulation, and more.

Both schemes aim to make homes warmer, more affordable to run, and better for the environment.

Not sure where to start?

If you’re unsure whether your home is already insulated or you’d like help checking if you qualify for one of the schemes, we’re here to help. We can guide you through a quick eligibility check and connect you with approved installers if needed.