How much does cavity wall insulation cost in 2024?

If your home was built post-1920, it probably has cavity walls. The good news? These are quick, easy and relatively cost-effective to insulate.

Plus, doing so comes with tons of benefits – including improving your home’s energy efficiency and cutting your heating bills. But how much does cavity wall insulation cost?

Here, you’ll find everything you need to know. From average cavity wall insulation prices to the factors you’ll need to consider for this home improvement. But first…

What is cavity wall insulation?

If your home has cavity walls, this means its walls are made of two ‘skins’ with a gap between them.

Cavity wall insulation involves filling this gap with insulating material to prevent heat from escaping.

Normally, this is done by drilling small holes in your walls, before injecting insulation into the cavity. Then, the holes are filled back in.

In the UK, there are four common materials that are used for cavity wall insulation, each with its own unique benefits.

Mineral wool

This material is very common in UK homes as it’s easy to install and cost-effective. It can be made from igneous rocks (known as rockwool), recycled glass (glass wool), or sand.

Polyurethane foam

Also known as cavity foam insulation, polyurethane foam has the best insulating properties out of all the common materials – however, it does shrink over time.

Expanded polystyrene beads (EPS)

EPS beads are little beads that are stuck together with a bonding agent. This material costs a bit more than mineral wool but is a slightly better insulator. Plus, it’s recyclable!

Cavity batts

Cavity batts are made from mineral wool that’s compressed into slabs and covered with a water-resistant film. They’re lightweight and easy to handle but they can’t be retrofitted. Rather, they can only be installed during the process of building a home.

What are the benefits of cavity wall insulation?

Wondering why you should invest in cavity wall insulation?

Here are some of the main benefits of cavity wall insulation in the UK:

• Lower energy bills
• A warmer home
• Reduced carbon footprint
• Quick and easy installation

Financially savvy homeowners will be excited to hear that you should be able to recoup the costs of cavity wall insulation in under five years!

But it’s also a no-brainer for eco-conscious homeowners looking to reduce their carbon footprint by improving their home’s energy efficiency.

How much does cavity wall insulation cost in the UK?

Now on to the all-important costs. The cost of cavity wall insulation can range from around £950 to £4,600, depending on the size of your home.

Average cost of cavity wall insulation by property type

As you might expect, bigger properties come with higher cavity wall insulation costs – simply because there’s more wall space to insulate!

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 can of course vary from property to property.

The best way to get an accurate cavity wall insulation price for your home is to get a quote from an expert.

We always recommend getting 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 cost of cavity wall insulation per m² can vary depending on which insulating material you choose.

• At the lower end of the price scale, you’re looking at around £25 - £30 per m² for glass wool
• Meanwhile, at the higher end, you can expect to pay around £30 - £65 per m² for polyurethane foam

That said, it’s important not to look at price alone when you’re considering which insulating material to choose.

Although polyurethane foam falls at the higher end of the price scale, it’s the best insulator out of all the common materials – meaning you may be able to recoup your investment quicker!

Learn more about the different options available in our expert cavity wall insulation guide.

Additional wall insulation costs

When you’re budgeting for cavity wall insulation, there are some additional costs you may need to factor in as part of the project.

1. Initial survey

Before you commit to cavity wall insulation, you’ll need to hire a surveyor to inspect your walls.

They’ll be able to confirm whether cavity wall insulation is a suitable option for your property, check whether your walls are in good shape, and outline any preparatory work needed.

A cavity wall insulation survey can cost up to £300. 

However, most installers will offer a free inspection if you choose their company for installation.

2. Additional repairs

If your surveyor flags that your cavity walls aren’t in the best shape, you might need to budget for repair work before you can go ahead with the cavity wall insulation.

Any exterior cracks will need to be repaired to make sure your new insulation isn’t vulnerable to dampness. Brick wall repair costs typically range from £240 - £300 per day.

Plus, any wall ties that have loosened over time will need to be replaced. This typically costs around £30 - £50 per m², but is non-negotiable as the wall ties are responsible for securing the two wall leaves at an even width.

3. Loft insulation

To get the maximum benefit from your cavity wall insulation, it’s important to make sure that the rest of your home is well-insulated too.

In particular, many companies provide packages that combine both cavity wall insulation and loft insulation.

Insulating your loft with quilt insulation typically costs between £654 – £1,206. However, you may be able to access lower prices by choosing a package that combines it with cavity wall insulation.

4. Removing existing insulation

Does your home already have cavity wall insulation?

Older homes may already have cavity wall insulation that has become outdated. Or, perhaps your existing insulation has become compressed, damaged by mould, or infested with vermin.

Issues can also arise if your cavity wall insulation wasn’t installed properly to begin with.

Whatever the reasons, unfit cavity wall insulation will need to be removed before it’s replaced with new insulation that’s fit for purpose.

Removing cavity wall insulation from a whole house typically costs between £1,680 – £2,520 – although many companies will be able to quote you a bespoke price for a full insulation replacement.

Factors affecting the cost of cavity wall insulation

As well as the additional costs above, there are a few other factors to account for when calculating 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

Don’t worry! An expert installer will be able to visit your property to give you an idea of how much you can expect to pay for your bespoke project.

Simply enter your postcode below to find a trusted professional near you.

Cavity wall insulation grants

Although cavity wall insulation can help to save you money in the long run, it does come with an upfront cost. Luckily, there are some cavity wall insulation grants available that may be able to help.

UK government grants for wall insulation

There are two key government grant schemes that 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 by covering part of the cost.

Head over to the Gov.uk website to check whether you might be eligible for the GBIS or ECO4 schemes.

Grants from UK energy suppliers

Many UK energy suppliers also give out grants and are able to provide cavity wall insulation for low-income households.

This includes suppliers such as British Gas, EDF Energy, E.On, Npower, and Scottish Power.

You can find a full list of energy companies that are obligated to help homeowners through ECO4 on Ofgem’s website.

On Checkatrade, you'll only find trades who meet our high standards and pass up to 12 checks.

Find a qualified cavity wall insulation specialist near you

Ready to reap the benefits of cavity wall insulation? Then it’s time to find the best professional for the job.

Who can install cavity wall insulation?

Cavity wall insulation can’t be installed by just anybody. Rather, you’ll need to look for a registered installer who’s a member of the National Insulation Association (NIA), the Cavity Insulation Guarantee Agency (CIGA), or the British Board of Agrément (BBA).

This ensures that your installer has the skills, qualifications, and experience needed to check your home’s suitability for cavity wall insulation, recommend the best type for you, and install it to a high standard.

It will also give you peace of mind that your insulation will be installed in compliance with regulations and building control.

Find approved installers with Checkatrade

All our tradespeople have to pass up to 12 checks to be listed on our directory – so, you know they’re professionals you can trust.

In fact, we’re so confident in the quality of the trades on Checkatrade that if you book through us, we guarantee their work up to £1,000 (guaranteed for 12 months – Eligibility and T&Cs apply). Simply enter your postcode below to get started.

FAQs

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

If your property has cavity walls, it’s likely to be suitable for cavity wall insulation.

However, there are exceptions – for instance, if your property has timber frames or the wall cavities aren’t wide enough for installation.

A professional installer will be able to assess your home’s suitability and recommend the best type of cavity wall insulation for your needs.

How do I know if I have cavity walls?

The age of your home is a great place to start. As a general rule, properties with cavity walls started being built in the 1920s and were a popular technique until building regulations changed in the mid-1980s.

Another clue is the appearance of your walls. If you have cavity walls, the bricks will usually be arranged in an even pattern, and all the bricks will be laid lengthways. If your bricks are arranged in an alternating pattern, producing rows of what looks like long and short bricks, the chances are you have solid walls instead.

Don’t worry if you’re not sure. A professional installer will be able to tell you for certain whether your property has cavity walls. They can check whether or not the walls are solid with what’s known as a borescope inspection, which involves drilling a small hole in your wall.

How long does cavity wall insulation last?

Cavity wall insulation typically lasts around 25 years.

However, it could last even longer depending on factors like which insulating material you choose, the quality of installation, and the condition of your walls.

How long does it take to install cavity wall insulation?

It should take an experienced professional around two hours to insulate cavity walls in an average house with easily accessible walls.

Can I install cavity wall insulation myself?

No, you can’t install cavity wall insulation yourself. Rather, you’ll need a registered installer to carry out the work for you, who’s a member of the National Insulation Association (NIA), the Cavity Insulation Guarantee Agency (CIGA), or the British Board of Agrément (BBA).

What types of insulation are used in cavity walls?

There are four main types of insulation used in cavity walls in the UK. These are:

• Mineral wool
• Polyurethane foam
• Expanded polystyrene beads (EPS)
• Cavity batts

How much can I save on energy bills with cavity wall insulation?

Cavity wall insulation savings can be quite significant. How much you can save on your energy bills with cavity wall insulation will depend on the size of your home and your energy usage.

The Energy Saving Trust estimates that a mid-terrace house could save roughly £160 per year, while a detached house could save a whopping £470 per year!

How is cavity wall insulation installed?

Cavity wall insulation is usually installed by drilling small holes in the mortar of your walls. Then, the insulating material is injected into the cavity and the holes are refilled.

Can cavity wall insulation cause damp?

Yes, cavity wall insulation can cause damp if it’s not installed correctly.

Plus, fully filling the cavity with insulation can increase the risk of rain penetration.

That said, damp caused by cavity wall insulation is rare when it’s installed properly.

What is the average payback period for cavity wall insulation?

You should be able to recoup the costs of cavity wall insulation in under five years.

Does cavity wall insulation add value to my home?

Yes, cavity wall insulation can add value to your home, as a well-insulated, energy-efficient property will be attractive to buyers.

How do I remove cavity wall insulation if needed?

To remove cavity wall insulation, a professional will usually blow compressed air into the cavity while collecting the old insulation with an industrial vacuum.