How to buy wall insulation Install wall insulation and save
A house before and after cavity wall insulation installation (image courtesy of Horton Levi Ltd)
More than a third of all heat lost from an uninsulated home escapes through the walls, so it shouldn't be a surprise to learn that installing wall insulation and loft insulation are often the most cost-effective measures you can make to save energy in your home.
You could save up to £135 a year on your heating bills by insulating cavity walls, or around £445 to £475 a year by insulating solid walls.
The thermal images on the right show the same house before and after cavity wall insulation was fitted. It shows that with insulation, there is less heat loss and the heat is more uniformly spread around the house.
How wall insulation works
Wall insulation acts as a blanket that prevents heat from escaping through the walls of your home. It can also help to stop your home getting too hot in summer.
The type of wall insulation you’ll need depends on whether your home has cavity or solid walls. Both types should be installed by a professional installer.
Cavity wall insulation
Cavity wall insulation is injected through the outer wall of your home into the space between the inner and outer leaves of brickwork that make up cavity walls.
It's very cost-effective – it costs between £100 and £350 and should pay for itself in around nine months to three years through the savings you'll make on your heating bills.
Most homes built from 1920 onwards have cavity walls
When Which? investigated cavity wall insulation sales practices in early 2011, we uncovered some concerns about assessments, price differences and poor advice. To make sure you're paying the right price and getting the right advice, see our cavity wall insulation section and watch our undercover insulation installation video.
Solid wall insulation
External wall insulation is much more expensive than cavity wall insulation, but could save you around £445-475 a year on your energy bills.
Solid wall insulation can be applied to either the inside or outside of solid walls. A professional installer can advise on which option is most suitable for your home. Our solid wall insulation page has more information about the costs and options.
Solid wall insulation could save you around £445-£475 a year on your energy bills
Loft and floor insulation
If you already have wall insulation, or want to make additional energy-saving home improvements, you could also consider installing loft or floor insulation. See our guide to loft insulation and wall insulation FAQs section for more information.
Other home energy efficiency measures include fitting a jacket to your boiler and installing double glazing.
Cheaper wall insulation
There are various government initiatives that provide discounts on the price of wall and loft insulation.
If you are aged 70 or over, or receive certain benefits, you could even get loft and cavity wall insulation installed completely free of charge. Some councils also offer discounts and free insulation for 'priority' groups. Offers change all the time and can be location-specific so, before carrying out any wall insulation work, check whether an energy grant or special offer is available.
Our full guide to energy grants has more information on which grants are available and how to apply.
The Energy Saving Trust's grants and offers database will also help you to find contact details for local schemes – or you can call your local EST advice centre on 0800 512 012.
An Energy Performance Certificate (EPC) shows you how energy efficient a house is
Insulation and home energy efficiency ratings
Home's Energy Performance Certificate (EPC) shows an overall energy-efficiency rating for your home from A-G.
‘A’ represents the most energy efficient properties and ‘G’ the worst. The EPC also contains advice on how to cut carbon emissions and fuel bills by making home improvements.
Fitting insulation is an effective way of raising your home’s energy efficiency rating. If you don't have insulation installed, the EPC will recommend the type and level of insulation required for maximum efficiency.
- Read our wall insulation FAQs
- Find out about loft insulation
- Save money with an energy efficiency grant
