Cavity wall insulation

Did you know that around a third of all the heat lost in an un-insulated home is through the walls? Insulating cavity walls reduces heat loss and can save you around £160 a year on your fuel bills.

Cavity wall insulation - what's it all about?

If your home was built from 1920 onwards, the chances are that its external walls are made of two layers with a small gap or `cavity' between them. This means they are `cavity walls'.

Insulating your cavity walls means filling that gap - with very good reason.

• Why insulate your cavity walls?
• What could you save?
• Could cavity wall insulationn work for your home?
• How do I get cavity wall insulation?
• Where can you go for more advice?

Why insulate your cavity walls?

Cavity wall insulation is an effective way to save energy and money at home. A well insulated house keeps warmth exactly where you need it - indoors.

So, insulating your cavity walls will help you to heat your home more efficiently. Using less energy reduces carbon dioxide emissions (CO₂): one of the biggest causes of climate change. You will also save money on your bills too.

Cavity wall insulation can also help to reduce condensation inside the house if it is a problem on external walls.

Find out how cavity wall insulation works

What could you save?

Cavity wall insulation is so cost effective that it will pay for itself over and over again. The better insulated your home, the less energy you need to keep it warm - and the more money you'll save.

In fact, by insulating your cavity walls you could cut your heating costs by up to 15%. By saving energy, your household will produce less CO₂. So, insulating your cavity walls is a great way to help fight climate change.

Let's do the maths*

Measure	Annual saving per year (£)	Installed cost £	Installed payback	CO 2 saving per year
Cavity wall insulation	Around £160	Around £250	Around 2 years	Around 800kg

The installed cost includes the subsidy available from the major energy suppliers under the Carbon Emissions Reduction Target (CERT); the typical unsubsidised installed cost is around £500

*Estimated figures based on insulating a gas-heated, semi-detached home with three bedrooms.

There are grants and offers available to help pay for cavity wall insulation - you can search our grants and offers database to see what's available or call your local advice centre free on 0800 512 012, they'll be happy to help.

Could cavity wall insulation work for your home?

Generally speaking, your home will be suitable for cavity wall insulation if:

• its external walls are unfilled cavity walls.
• the masonry/brick work of your property is in good condition.
• your cavity is at least 50mm wide

If your home was built in the last 10 years it is likely that it will have cavity walls which are already insulated. In all cases if you're thinking about cavity wall insulation, always check with a registered installer who will assess whether your home ticks all the right boxes. Your local Energy Saving Trust advice centre can put you in contact with a registered installer - just call 0800 512 012.

In the meantime, find out how to identify whether you have cavity walls.

Or, if you're sure your home is not suitable for cavity wall insulation, why not think about solid wall insulation?

Did you know?

An un-insulated home loses around a third of its heat through its external walls. If every UK household that is suitable for cavity wall insulation installed it, we could save more than £750 million and 6.5 million tonnes of CO₂ every year.

How do you get cavity wall insulation?

Filling cavity walls is not a job you can do yourself. Installation must always be carried out by a registered installer. Find out how to get cavity wall insulation installed.

What is a registered installer?

We consider a registered installer for cavity wall insulation being one that is a member of any one of the following organisations:

1. The National Insulation Association (NIA)
2. The Cavity Insulation Guarantee Agency (CIGA)
3. The British Board of Agrement (BBA)

Two key things to look out for when considering an installer:

1. They sign up to a code of professional practice like those provided by the NIA
2. The installation is guaranteed for 25 years by CIGA.

For these installers, the job is simple, quick - and makes no mess. Typically, a home will take around two hours to insulate, depending on how big your house is and how accessible its external cavity walls are. Watch our video to see how it's done.

Find out all about installation: how cavity wall insulation is installed, who will install it - and how a grant or offer could help with the costs.

Where can you go for more advice?

Call your local Energy Saving Trust advice centre (insert link to advice centre page) on 0800 512 012 for free, impartial, one-to-one advice on saving energy at home.

If you are interested to know more about cavity wall insulation our advisors will be able to help you with any questions you might have. They can explain any practical issues and can put you in touch with local installers. A registered installer will assess whether your home is suitable for cavity wall insulation.

We'll also tell you about any grants and offers available to help with your planned home energy improvements. So, it pays to call freephone 0800 512 012.

Useful links for cavity wall insulation:

• Find out how cavity wall insulation works
• Find out how to identify whether you have cavity walls
• Find out how to get cavity wall insulation installed

Saving assumptions