Cavity wall insulation is injected into the cavity between the inner and outer leaves of brickwork that make up the external wall. An installer will do this from the outside of your home. There is a variety of different insulating materials, but they all work in the same way. By combining with the captive air within the cavity, the insulation acts as a barrier to heat loss. With most homes built before 1976, cavity wall insulation can cut heat loss through walls by two-thirds.
Cavity wall insulation brings many benefits, and these include
- Reduced heat loss through walls by up to two-thirds.
- Reduced heating bills by up to one third.
- A warmer, more comfortable home in winter
- A cooler house in summer.
- Increased value of your home.
- Reduced risk of condensation forming on the inside surface of the walls
Frequently asked questions
Is my house suitable for cavity wall insulation?
Before the installation, the contractor will undertake an assessment of your home. This will confirm:
- Whether your home has cavity walls.
- Whether or not your cavities have already been insulated.
- That your walls are in good condition, and suitable for insulation.
This assessment is normally free of charge, and will be undertaken by a surveyor or technician before installation.
How much will it cost?
An average grant aided installation will cost on average between £100 and £200 and you'll find that, with the savings you make on your heating bills, cavity wall insulation will pay for itself in just over a year.
How long will it take?
Between two to three hours for a three bedroom semi-detached house.
Will it make a mess?
No. The insulation is injected from the outside, so the installers will not be working in the house.
What about filling the holes?
All the holes through which the insulation is injected are filled with mortar to match the existing colour and texture as closely as possible. On pebbledash finishes, pebbles are added to the surface to match the existing finish. After weathering, the holes are difficult to see.
What do they use as insulation?
The material used will most likely be mineral wool or polystyrene beads. It will be properly accredited as a building material, guaranteed by the Cavity Insulation Guarantee Agency (CIGA),and will be installed by a certified contractor.
Will the work be guaranteed?
If you use a professional, the work will be guaranteed for 25 years by CIGA.
Does cavity wall insulation increase the risk of penetration by damp or rain?
There is no evidence that cavity wall insulation results in a greater risk. However, the structural condition of your walls is critical, and your installer will assess the risk before proceeding.
How can I find a registered installer?
Contact your local Energy Efficiency Advice Centre on 0800 512 012 who will be able to give you information about installers and grant and offers in your area. Alternatively, contact CIGA or the National Insulation Association (NIA).
Where can I find more information about all types of home insulation?
Visit the NIA website from the link on this page for information on all types of home insulation - cavity wall insulation, loft insulation, draught proofing and internal flexible linings.