Average Price to Have Cavity Wall Insulated

Welcome to Quotation Check – the leading home improvement cost comparison site in the United Kingdom. How much does it cost to fill a cavity wall with insulation to reduce heating bills? We have researched the prices charged by tradespeople for this type of work so explore our guideline prices on this page. We last updated the content of this page on the .

What You Get For Your Money

Here is a list of everything you can expect when it comes to cavity wall insulation:

  • Full inspection of the property, it may already have cavity wall insulation or it may not be suitable for this type of work (more about that later).
  • The installers will drill 20mm holes every metre throughout the wall.
  • The material will then be blown into the cavity, a pressure gauge will tell us when enough has been inserted.
  • All holes will usually be filled with cement.
  • A certificate or letter confirming the work has been completed.

Not Every House is Suitable for Cavity Wall Insulation

When it comes to this type of work, we know our stuff. Most houses are suitable for cavity wall insulation, but not all:

Concrete Gutters – If you have concrete gutters then leaks may result in the cavity wall insulation becoming soaked with water, this can lead to damp patches on both the internal and external walls. This does not affect normal gutters (metal, plastic etc). It is important that the concrete gutters are first lined with either a rubber or aluminium product to prevent rainwater leaking into the cavity wall.

Wind Driven Rain – If your property is located on an exposed location and suffers from wind driven rain frequently coming into contact with the external wall, it may seep into the cavity causing the insulation to become soaked. It is then only a matter of time until it leaves long term damp patches, again on both internal and external walls.

Non-Standard Wall Construction – Some walls don’t have any cavity at all (called solid walls), while some have a cavity that that made from alternating brick patterns that may prevent an installer from injecting the insulation.

cavity wall being filled

Cavity Wall Insulation Cost

We contacted 12 cavity wall insulators and asked them to cost for cavity wall insulation to a typical 3-bed semi detached house with 3 external walls:

LocationSmall Business /TraderLarger Business (5+ employees)
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London AreaN/A£500.00
South, SW and MidlandsN/A£500.00
Outer Region and NorthN/A£475.00

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How to Get a Hefty Discount

Most gas/electric suppliers offer free or heavily discounted loft and cavity wall insulation. These are based on where you live, the type of property you live in and also whether you receive certain benefits.

Local councils sometimes offer incentives to have wall insulation, so do check your council’s website and check for any offers.

How Long Does the Work Take?

Usually around 2 hours for a semi detached 3 bed house. On rare occasions, access issues may mean a small amount of scaffold is required.

Is the Work Messy? Are any Special Precautions Required?

The work does involve drilling 20mm holes into the external wall every square metre. This will result in some vibrations through the property and some dust which may fall on patios, flower beds etc. It may be worth moving or covering any delicate or valuable items.

How Will the Holes be Filled?

The holes in the wall will be filled with cement, this is fine for brick walls but if you have render (such as this) the cement will need to be painted. This won’t be done by the cavity wall insulators, it will be something that has to be arranged by yourself.

Touch up paint can look patchy, so consider repainting the entire wall.

Expected Savings

Approximately 1/3 of heat loss in an uninsulated home will be through the walls.

According to the Energy Saving Trust the following savings can be achieved per year:

Detached Property – £275.00

Semi Detached – £160.00

Terraced – £105.00

Flat – £90.00

The statistics are based on a home with gas central heating.

What is the Insulation Made From?

There are several different types of cavity wall insulation. Mineral wool, granules and beads are the most common. Foam can also be inserted into the walls.

We Want Your Feedback

What do you think of our article about cavity wall insulation costs and prices? You can leave a comment at the base of the page.

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5 Responses to “Average Price to Have Cavity Wall Insulated”

  1. myrooffOctober 4, 2016 at 4:46 pm #

    Thanks but what about the cost of insulation?

  2. Gordon FisherNovember 23, 2016 at 3:25 pm #

    Hi there

    I would like to know the cost of cavity wall insulation for a linked bungalow, 3 bedrooms, 6 rooms altogether and a conservatory which is not heated as yet.

    Thank you

  3. john kissaneDecember 11, 2016 at 8:44 pm #

    I would like to know the cost of cavity wall insulation to one wall of a flat about 2.5 metres by 2.5 metres

    • Colin MoullDecember 18, 2016 at 6:42 am #

      You could try Wallrock Thermal Liner 10m x 75cm supplied by toolstation (free delivery), its applied a bit like wallpaper but insulates and leaves a robust surface to decorate as an alternative to cavity wall insulation.

      I think you’ll find most insulation firms will not want to tackle such a small job.

  4. Des ShillingfordDecember 29, 2016 at 8:51 am #

    Need cavity insulation in extension

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