The latest news, blog articles, renovation hints and tips from our team and carefully selected experts.

Pitfalls of Cavity Wall Insulation

This month’s guest expert is Sunday Telegraph columnist and building expert Jeff Howell who provides an overview on cavity wall insulation for property investors


Investing in property for the rental market can come with its ups and downs and one particular problem that is becoming a regular issue is cavity wall insulation.

What’s the problem?

Cavity wall insulation isn’t the issue, some properties benefit from it. But since the government started to offer grants and subsidised installation, a lot of companies thought it was an easy way to make a quick buck and some homes suffered from faulty installation, products and miss-selling.

How does this affect me?

To keep this short, CWI may not affect you but there are properties that need a cavity to stop wind driven rain from entering home and causing damp. There are now complaints that homes in these areas are now suffering from damp due to the cavities being filled (usually with mineral wool).

For more information on this, you can visit my website for details.

How do I know if it’s CWI causing damp?

Diagnosing cavity wall problems is not as tricky some may think and the most effective way is to use a surveyor who has an infrared imaging camera. This device will show you if the insulation is installed incorrectly with cold-spots illustrated in the report.

If your property has been filled with blown fibre wool, you can instruct a surveyor or extraction company to remove a brick at the bottom of the property and see if it is damp.

Wet Cavity Wall Fill

Removing Cavity Insulation

There has been a surge in newly formed extraction companies to help remove the insulation. But what’s concerning is that a lot of these firms are owned by the directors of the dissolved installation companies.

My advice is to contact your Tenant or previous owner and see if they have a guarantee from the installation company, as you may be able to claim the extraction from CIGA.

Who are CIGA?

This is the guarantee agency set-up to cover any faulty insulation and all installers have been advised to register with them. If the firm is registered, then they will help you further.

What if the installer is not registered with CIGA?

Then you may need talk to the insulation firm yourself and see if you can claim anything back direct.

There are now a number of specialist solicitors who have taken on cases and had considerable success in claiming back damages. They will also carry out a survey and diagnoses and let you know if you have a case.

Visit for  free guidance from professionals that will help diagnose and resolve your damp problems


So you if you’re thinking about investing in a property, I would certainly instruct your surveyor to check the cavities. This will not be included in a standard homebuyer’s report but there are some mortgage companies becoming a bit savvier on this subject. 

cavity wall insulation