Cavity walls

About a third of heat loss in uninsulated homes is lost through the walls. So it is usually worth making sure that your walls are as well insulated as possible.


The first question is what kind of walls your home has. Most buildings constructed since the 1930’s have cavity walls, which can be identified by having only the sides of the bricks visible, no ends (as with a solid wall):

Cavity walls can be insulated in the cavity, using either a foam insulant; a kind of wool made from minerals; or beads made from carbon, which are the most energy-efficient choice. Cavity wall insulation is not a DIY job, but it is easy for a professional to do. More information and recommended suppliers can be found through the National Insulation Association. Most buildings constructed since the 1990’s have a filled cavity.

Geek says

  • If you are in doubt about whether your cavity walls have been insulated, you could get a thermal image which often shows how good or bad they are. LCON usually arranges for a camera to be available during the winter. Surveyors can also check for the existence of the filler.
  • Don’t forget the value of “old fashioned” solutions such as putting bookcases against walls and doing DIY draught-proofing.
  • Make changes when you are doing other building work: it makes the pain easier to bear!
  • When government incentives were brought in to encourage people to have their cavity walls insulated, some companies did very poor jobs – so even if you know your walls were insulated, it’s worth checking how well it was done, using the thermal imaging method. If you find gaps in the insulation, you should be able to go back to the company that did the work (if they still exist and you know who it was) and require them to do it again.

Local experiences

Judith had a thermal imaging survey done by LCON after she had the cavity walls surveyed and filled by Energy Care group. The images revealed that the insulation hadn’t quite got into all the corners of the walls, leaving cold, leaky areas. Once she reported the findings they came back promptly and did the remedial work without question. She would recommend a thermal check after any work like this where it isn’t possible to see the results.


Useful links

Thermal imaging of cavity walls

Advice on hard to treat cavity walls.

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