Cavity Wall Insulation can save energy and money
Have my neighbours done this?
What is it?
The most cost effective way of reducing heat loss from walls
What will it save me?
Could save up to £150 per year
How do I get it?
Insulating an existing wall needs a specialist contractor
What does it cost?
Costs around £750 depending on house size
What are the technical details?
New houses are required to have effectively insulated walls but existing homes can be made just as efficient by adding insulation. Most houses built after 1945 will have a cavity built within the wall which can be insulated although newer houses may be fully or part filled with insulation when the house was built.
If the wall is in good condition it can, in most cases, be filled with thermal insulation through holes drilled in the outer wall and insulation blown into the cavity. If the cavity is narrow or has other problems it may be necessary to adopt the insulation method for solid walls.
Although modern timber frame homes normally have a cavity, they can‘t be filled in the same way as masonry walls without risking condensation issues. It’s also unwise to insulate the cavity if there is a known damp penetration problem. Any such issues should be resolved and the wall allowed to dry out first.
Retro fitted cavity wall insulation can be in the form of mineral fibres which bind together in the wall to form a solid mat, or lightweight beads which are injected with a resin to make them stick together in the wall. Either system will achieve a well-insulated cavity wall that will reduce the heat loss from the wall by up to 50%.
This is definitely not a DIY job as it requires specialist pumping equipment and may also require scaffold if there are external obstructions such as a conservatory.