Cavity Wall Insulation Cost Calculator UK | Free Estimate
Not sure how much cavity wall insulation could cost for your home?
Use this calculator to get a quick estimate, check likely savings, and see whether your property may be suitable.
Likely suitable. Most homes from this period have unfilled cavity walls.
We recommend getting a professional survey to confirm your wall type and condition. You should also check if you qualify for the Great British Insulation Scheme.
How this calculator works
Our cavity wall insulation cost calculator uses average UK installation prices to give you a realistic estimate. We take your property type and size into account to work out the likely wall area that needs insulating. The savings estimates are based on typical energy bill reductions seen in homes upgrading from unfilled cavities to standard insulation materials, such as EPS beads or mineral wool.
How Cavity Wall Insulation Works
What affects cavity wall insulation cost?
While our calculator gives you a strong basic estimate, the final quote from an installer may vary due to several factors:
Insulation Material
EPS (polystyrene) beads are highly effective and popular, but they can cost slightly more than traditional blown mineral wool. Polyurethane foam is the most expensive option, but it offers the best thermal performance for narrow cavities.
Wall Area
Larger detached homes naturally require more material and labour than mid-terraced properties.
Access Issues
If your home requires scaffolding, such as for a high flat or hard-to-reach walls, the installation cost will increase.
Wall Condition
If your brickwork needs repointing or there are existing damp issues, these problems must be fixed before the insulation is injected.
Existing Insulation
If old or damaged insulation needs to be removed first, this can add £300 to £600+ to your total bill.
Is your home suitable for cavity wall insulation?
Not every home is suitable for cavity wall insulation, and not every property should have its cavities filled. A professional survey is always required, but here are the general rules:
Build Year
Homes built before 1920 usually have solid walls, which means there is no cavity. Homes built between 1920 and 1990 are the best candidates for cavity wall insulation. Homes built after 1990 often already have insulation in place.
Cavity Width
The gap between your inner and outer walls usually needs to be at least 50mm wide.
Exposure to Rain
If your home is highly exposed to driving rain, which is common in some coastal or western parts of the UK, standard insulation may bridge the cavity and cause damp. In this case, special materials or external wall insulation may be recommended instead.
Condition
Your external walls should be in good condition, with no severe cracks or damp.
Grants, funding, and support options
Before paying the full cost, check whether you qualify for UK government support. You may be able to get cavity wall insulation installed free of charge or at a heavily subsidised rate.
The Great British Insulation Scheme (GBIS)
This scheme helps families in lower council tax bands whose homes have poor EPC ratings to improve their home's energy efficiency. It is specifically designed for single-measure upgrades, such as cavity wall insulation.
Check your eligibility on GOV.UK →