COST GUIDES
How much does cavity wall insulation cost in 2026?
Updated 06/26
Thinking about getting cavity wall insulation in your property? Get the full 2026 price breakdown below, including what affects the cost and how to find a checked installer.
Fast Facts
Cavity wall insulation costs in the UK range from around £950 to £4,600
Prices vary based on your property size, wall condition, and the insulating material used
Most homeowners recoup the cost in under five years, and could save up to £470 per year on energy bills
How much does cavity wall insulation cost in the UK?
Cavity wall insulation costs range from around £950 to £4,600, depending on the size of your home.
| Example property type | Average price |
|---|---|
| Detached property | £4,600 |
| Semi-detached property | £2,700 |
| Mid-terrace | £1,800 |
| Bungalow | £2,400 |
| Flat | £950 |
| Last updated: July 2026 Our costs are ballpark averages - get a local tradesperson to quote now | |
Average cost of cavity wall insulation by property type
Bigger properties cost more to insulate, because there is simply more wall space to fill.
As a general guide, expect to pay around:
£1,800 to insulate a mid-terrace house
£2,700 for a semi-detached property
£4,600 for a detached house
That said, this varies from property to property. The best way to get an accurate price for your home is to get a quote from an installer.
It's always best to get at least three quotes so you can compare reputable companies and check you're getting a fair and competitive price for the work.
How much is cavity wall insulation per m²?
The per-m² cost depends on the insulating material you choose.
At the lower end, glass wool costs around £25 - £30 per m²
At the higher end, polyurethane foam costs around £30 - £65 per m²
Don't just look at price alone when choosing a material. Although polyurethane foam costs more upfront, it is the best insulator of the common types, so you may recoup your investment faster.
Learn more about the different options available in our expert cavity wall insulation guide.
Cavity wall insulation cost: job estimator tool
You can get an estimate for your cavity wall installation costs by using out job estimate calculator.
Enter a few details about your home and what kind of insulation you want, and the tool will use Checkatrade cost data to give you an approximate quote. Give it a go!
Job Estimate Calculator
Additional wall insulation costs
When budgeting for cavity wall insulation, there are some extra costs you may need to factor in.
1. Initial survey
Before committing to cavity wall insulation, you will need a surveyor to inspect your walls. They will confirm whether your home is suitable, check that your walls are in good shape, and outline any preparatory work needed.
A cavity wall insulation survey can cost up to £300.
Most installers will offer a free inspection if you choose their company for the work.
2. Additional repairs
If your surveyor flags that your walls are not in the best shape, budget for repair work before the insulation goes in.
Any exterior cracks need to be repaired to protect your new insulation from damp. Brick wall repair costs typically range from £240 - £300 per day.
Any wall ties that have loosened over time will also need to be replaced. This typically costs around £30 - £50 per m² and is non-negotiable: wall ties are responsible for holding the two wall leaves at an even width.
3. Loft insulation
To get the most from your cavity wall insulation, the rest of your home should be well-insulated too. Many companies offer packages that combine cavity wall and loft insulation together, which can work out cheaper than booking separately.
Loft insulation with basic quilt typically costs around £725 for an average home.
4. Cavity wall insulation removal
If your existing cavity wall insulation is causing damp or has failed, you may need to have it removed before fitting new insulation.
Cavity wall insulation removal typically costs between £1,680 and £2,520 for a semi-detached house, depending on the material and accessibility.
You can find full details in our cavity wall insulation removal cost guide.
Factors affecting the cost of cavity wall insulation
As well as the additional costs above, a few other factors affect your overall cavity wall insulation price. These include:
Insulating material
Property size
Property age
Condition of your walls
Cavity space between the wall leaves
Wall accessibility
Whether scaffolding is required
Location
An installer will be able to visit your property and give you a bespoke price. Request a quote to get experienced local installers to contact you.
If your walls are not suitable for cavity wall insulation (for example, if they are solid or have irregular cavities), external wall insulation or retrofit insulation may be alternatives worth exploring.
What is cavity wall insulation?
If your home was built after 1920, it probably has cavity walls. These are made up of two layers of brick (or block) with a gap (the "cavity") between them. That gap is a natural route for heat to escape.
Cavity wall insulation fills that gap with an insulating material, slowing heat loss and making your home easier to warm.
Do you have cavity walls?
Most homes built post-1920 do.
A quick way to check is to measure the width of your external wall. If it is more than 260mm thick, you almost certainly have a cavity.
A surveyor can confirm this before any work begins.
What materials are used?
In the UK, there are four common materials used for cavity wall insulation, each with its own benefits.
Mineral wool
The most common choice in UK homes. It is easy to install, cost-effective, and made from igneous rocks (rockwool), recycled glass (glass wool), or sand.
Polyurethane foam
Also known as cavity foam insulation. It has the best insulating properties of all the common materials, though it does shrink over time.
Expanded polystyrene beads (EPS)
Small beads stuck together with a bonding agent. EPS costs a bit more than mineral wool but insulates slightly better. It is also recyclable.
Cavity batts
Mineral wool compressed into slabs and covered with a water-resistant film. Lightweight and easy to handle, but they can only be installed during a build, not retrofitted.
How long does cavity wall insulation take?
Cavity wall insulation typically takes around two hours for an average house with easily accessible walls. Larger properties or those with restricted access may take longer.
The installer drills small holes into the mortar of your external walls, injects the insulating material into the cavity, then fills the holes. It is a quick job compared with other insulation types - most homeowners can have the work done in the space of a morning.
Cavity wall insulation grants
Although cavity wall insulation saves you money in the long run, there is an upfront cost. There are grant schemes that may help.
UK government grants for wall insulation
Two main government schemes can help with the cost of cavity wall insulation:
The Great British Insulation Scheme (GBIS)
The Energy Company Obligation (ECO4)
Both are designed to help low-income and fuel-poor households, either by providing free insulation or covering part of the cost. Eligibility rules are updated periodically, so check the latest guidance before applying.
Head to Gov.uk to check whether you might be eligible for the GBIS or ECO4 schemes.
Some local councils also run insulation grant schemes via the ECO flex mechanism. Check your council's website for details.
Grants from UK energy suppliers
Many UK energy suppliers provide cavity wall insulation for low-income households. This includes British Gas, EDF Energy, E.On, Npower, and Scottish Power.
You can find a full list of obligated energy companies on Ofgem's website.
What are the benefits of cavity wall insulation?
Wondering whether it is worth the investment? Here are the main benefits of cavity wall insulation:
Lower energy bills
A warmer home
Reduced carbon footprint
Quick and easy installation
A potential boost to your home's EPC rating
You should be able to recoup the costs of cavity wall insulation in under five years. According to the Energy Saving Trust, a mid-terrace house could save roughly £160 per year, while a detached house could save £470 per year.
A better EPC rating also makes your home more attractive to buyers, and may help you meet energy efficiency requirements if you are a landlord.
Find a cavity wall insulation specialist near you
How to find an insulation installer
Finding a qualified insulation installer is straightforward with Checkatrade. We check and verify all of our members, so everyone in our directory meets our standards.
Use our quick and easy request a quote feature and we'll get local insulation installers to contact you directly. To get accurate quotes, be as detailed as you can:
The type of walls you have (cavity or solid)
Your property type and approximate size
Whether you have had an energy survey or EPC assessment
Any known issues such as damp or existing insulation that may have failed
Whether you are applying under the ECO4 or Great British Insulation Scheme
You can also find cavity wall insulation installers near you in our directory.
Find an insulation installer covering your area
Enter your postcode to get started. Or download the Checkatrade app to browse and hire tradespeople on the go.
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Cavity wall insulation cost checklist
Use our handy checklist to make sure you've got everything ticked off, so you get the most accurate quotes on your cavity wall insulation.
Cavity wall insulation cost checklist
Before contacting a tradesperson, here's what to check:
Cavity wall insulation cost FAQs
Most homes built after 1920 are suitable for cavity wall insulation. A quick way to check is to measure the thickness of your external wall: anything over 260mm likely has a cavity. A registered installer will carry out a survey to confirm suitability before starting any work.
It should take an experienced professional around two hours to insulate cavity walls in an average house with easily accessible walls.
No. Cavity wall insulation must be installed by a registered professional who is a member of the National Insulation Association (NIA), the Cavity Insulation Guarantee Agency (CIGA), or the British Board of Agrément (BBA).
There are four main types used in UK homes: mineral wool, polyurethane foam, expanded polystyrene beads (EPS), and cavity batts.
How much you save depends on the size of your home and your energy usage. The Energy Saving Trust estimates a mid-terrace house could save roughly £160 per year, while a detached house could save around £470 per year.
Cavity wall insulation is usually installed by drilling small holes in the mortar of your external walls. The insulating material is then injected into the cavity and the holes are refilled.
Yes, if it is not installed correctly. Fully filling the cavity can also increase the risk of rain penetration in some properties. That said, damp caused by cavity wall insulation is rare when the work is done properly by a registered installer.
You should be able to recoup the costs of cavity wall insulation in under five years.
Yes, cavity wall insulation can add value to your home. A well-insulated, energy-efficient property is attractive to buyers and typically earns a higher EPC rating.
To remove cavity wall insulation, a professional will usually blow compressed air into the cavity while collecting the old insulation with an industrial vacuum.
Yes, for most UK homeowners. The cost of insulating a semi-detached house is around £2,700, and according to the Energy Saving Trust, you could save up to £160 a year on your heating bills. That gives a payback period of well under five years. You also benefit from a warmer home and a better EPC rating.
Glass wool is generally the most affordable option, at around £25–£30 per m². Polyurethane foam costs more (around £30–£65 per m²) but is the best insulator of the common types, so it can pay back faster.
In most cases, no. Cavity wall insulation is considered permitted development in England and Wales. If your property is in a conservation area or is listed, check with your local planning authority before proceeding.
Need help with your home insulation? At Checkatrade we have a number of resources to help with your decisions, such as eco-friendly choices and planning guides.
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