Cavity Wall Insulation

Cavity Wall Insulation

What is cavity wall insulation?

Cavity wall insulation is where the space (cavity) between the external leaf and internal leaf of your homes external wall are filled with an insulation material. It can be fitted in both traditional (brick or block) buildings and timber framed buildings.

The insulation added to the cavity will reduced the heat lost from your home in turn reducing your heating bills and increasing your homes energy efficiency.

It is often fitted by drilling holes into the cavity and blowing an insulation material in. Make sure you check how these holes will be repaired/sealed before any work starts.

How do I know if my house is suitable for cavity wall insulation?

Most homes with cavity walls are suitable for cavity wall insulation as long as,

  • The cavities aren’t blocked in any way (for instance with debris or rubble).
  • The cavity is at least 50mm wide (you can measure the width of the wall in a window or doorway).
  • The external brickwork/ masonry is in good condition.
  • The house is not susceptible to damp and/or in a location exposed to high levels of wind-driven rain.


  • Increased energy efficiency.
  • Saving on heating bills.


The purpose of a cavity is to stop water penetrating into your home causing damp problems. Closing this cavity off by filling it with insulation can cause damp problems. We would not recommend cavity wall insulation for areas of high weather exposure.

Do I need planning permission?

Planning permission is not required unless your building is listed.

Do I need building warrant?

A building warrant is not required for cavity wall insulation.

Always make sure any work you get carried out is done so by a qualified company and a full guarantee is provided.

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