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Cavity Wall Insulation

What is cavity wall insulation?


Figure 1: Diagram showing how to identify the difference between a cavity wall and a solid wall.


If you want to find out which energy saving grants are available for you just fill in your details and we'll call you back to help.


Figure 2: Photograph showing mineral wool Insulation in a cavity wall

Do I need cavity wall insulation?

Buildings with a cavity wall construction (two walls with a gap in between them) were introduced in the 1920s in the UK. The cavity construction helps to prevent rainwater from tracking through the wall and causing damp problems inside a building, which is a common feature of solid wall properties.

Homes built after 2000 are likely to have been built with insulation boards in the cavity to comply with building regulations, so, in theory, properties with a cavity wall that were constructed between 1920 to 2000 can be retro-fitted with cavity wall insulation.

Is my property suitable for cavity wall insulation?

It is very important to have a surveyor check the walls of your property with a camera to see if it is suitable for cavity wall insulation to be retro fitted, as there are a number of reasons why it may not be suitable to be insulated. These include:

  • The building may be metal framed or timber framed – neither of which are suitable for retro-fit cavity wall insulation.

  • If the cement pointing between brickwork is in poor condition.

  • Dirty wall ties  (cement stuck to the wall ties).

  • If the building is exposed to a lot of driving rain (eg near the coast or on a hill).

  • If the brickwork is porous.

  • If the property does not have a damp proof course (D.P.C.)

  • If the cavity wall is too narrow (the cavity wall needs to be at least 50mm wide)

Read more: Cavity Wall Insulation Pros and Cons

If your property is deemed unsuitable for cavity fill insulation, the alternative is to have either External Wall Insulation or Internal Wall Insulation.

Whichever type of retrofit wall insulation you choose (Cavity Wall Insulation, External Wall Insulation or Internal Wall Insulation) it is important to have survey of your home to establish which is best suited for the building. 

Up to 50% of heat lost from a building is through the walls, so retrofit wall insulation can make your home much warmer as well as help to save you hundreds of pounds a year on fuel bills.



We are able to help obtain funding for Cavity Wall Insulation for some properties. An energy assessment will need to be carried out on your property to establish whether it is suitable for Cavity Wall Insulation to be installed and to calculate how much funding will be available.


This funding is based upon how much carbon dioxide will be saved by installing insulation within the cavities. The amount of funding varies and is allocated on a first-come, first-served basis. 


Please contact us on 0330 223 0333 to arrange a free, no-obligation survey of your property, or alternatively you can enter your details on our contact page and we will call you back to discuss your requirements.

Read more: ​How Long Does Cavity Wall Insulation Last?

Almost all new build houses are built with insulation in the cavity walls to prevent heat from escaping.  Existing properties can also have cavity wall insulation retro-fitted by drilling a series of small holes in the external walls and blowing insulation into the cavity under low pressure. There are a few different types of insulation that can be used – polystyrene bead, mineral wool or polyurethane foam. All of these materials have been used for retrofit cavity wall insulation in the UK for over 40 years and can significantly reduce heat loss via the walls.















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