Quotatis | Insulation Advice

Cavity wall insulation


Homes built since the mid-1930s have probably been built with a cavity wall. This provides a small space between two layers of bricks. It provides some thermal protection but that can be improved on.

To check if you have a cavity wall the best way is to look at the pattern of the bricks on the external wall. If the bricks are laid length-ways with one brick laid to cover the join of the bricks below – that’s a cavity wall. If the wall is laid one brick length-way and the next end-ways that’s a solid wall.

Cavity wall insulation needs to be undertaken by an expert. They have the equipment, and the expertise to judge exactly how much material is required to give your home good insulation.

The method is to inject the insulant into the gap between the two skins of the wall.

The material most normally used is foam, alternatives include mineral or glass fibre mixed with a binder of beads or granules.

All the materials are treated to be water resistant to prevent damp entering the building, and are also fire retardant.

These forms of insulation should come with a 25-year guarantee issued by CIGA (Cavity Insulation Guarantee Agency) so shop around.

A question to ask would-be installers is does the material and work comply to British Standards or the British Board of Agreement (BBS). If they don’t – go elsewhere.


      • Any problems with condensation need to be tackled before insulation is installed.
      • Walls must be dry before the work can be carried out as sealing in damp won’t solve anything.
      • You need a professional to check out what is causing the damp and how it can be eradicated – that includes inspecting damp courses to see if they are sound and fit for purpose.
      • It is vital not to cover any ventilation already provided in the building and to check if additional sources are recommended by the installer.

How long will it take to install cavity wall insulation?

The whole process shouldn’t take more than two or three hours, depending on the size of the property and access to the exterior walls.
The installer drills holes at regular intervals and injects the insulant through them. Once in place the holes are plugged – leaving little evidence that anything has been done.

How to help the installer

A sensible move is you tell your neighbours what is going on and, if applicable, advise them to move any cars so that they don’t get covered with dust.

Neighbours would probably also appreciate being warned that there will be some drilling going on for a little while.
Removing pictures or other valuables that might be dislodged through the vibration is recommended.


Facts & Figures You’ll Love To Share

  • Improving your home efficiency with insulation will help you to save hundreds of pounds every year on heating bills.
  • As heat naturally rises, loft lagging acts as a superb insulator to retain warmth in the home.
  • 20% of heat can be lost through inefficient walls, so consider wall cavity and solid wall insulation.
  • You could be wasting £200 a year on heat with inefficient windows. Consider replacement double glazing.

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Tom Crosswell

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