22nd July 2021
The cost of insulating your property’s walls depends on the size of your home, whether the walls are cavity or solid and the condition they’re in.
Installing wall insulation is one of the most cost-effective improvements you can make to your home. The savings you make on your heating bills means insulation could pay for itself in as little as nine months.
The picture above shows a solid wall (left) and a cavity wall (right). The brick pattern can often be an indication of the type of wall you might have.
Solid walls tend to be fortified with bricks laid across, rather than along, the wall. These will look like smaller, half-sized bricks from the front. A cavity wall will have all the bricks laid in the same direction, so they'll all look the same size.
If your home was built from 1920 onwards, it’s likely to have cavity walls. To be suitable for cavity wall insulation, the cavity should be at least 50mm wide and the walls need to be in good condition.
If your house was built in the past 20 years, it’s likely that the cavity walls were insulated when they were built.
Maybe. Under the Energy Company Obligation, some households are eligible for discounted or free insulation, but the eligibility criteria is complex and depends on the condition your property is in.
Wall cavities are designed to catch rain coming through the outer walls and divert it away from the inside of your property, so if cavity wall insulation is poorly fitted or used in the wrong place, it can cause damp problems.
But provided the insulation material is water-repellent and is installed correctly, damp shouldn’t be an issue.
Any installer registered with the Cavity Insulation Guarantee Agency (CIGA) should check whether your home is suitable. Their work and materials will be covered by a 25-year guarantee.
Some cavity walls are not suitable for cavity-wall insulation, including those regularly exposed to wind-driven rain.
Planning permission is not normally required for wall insulation.
However, if your property is listed, is in a conservation area or the insulation will change the appearance of your property, you should consult your local planning authority.
For cavity-wall insulation, choose an installer registered with one of the following organisations:
You should check that your installer has signed up to a code of professional practice, such as that offered by the NIA, and make sure the insulation installation is guaranteed for 25 years by the Cavity Insulation Guarantee Agency (CIGA).
The CIGA provides independent 25-year guarantees for cavity wall insulation fitted by registered installers in the UK and Channel Islands.
You can also use our Trusted Traders search tool above to find local fitters near you.
There are plenty of ways to improve your home's insulation and reduce your energy bills: