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How much does cavity wall insulation cost in 2024?

The prices in this guide are accurate, as of 2024*

Illustration of a row of houses with cost of cavity wall insulation labelled on it
Cost of cavity wall insulation on different properties

If you’re looking to make your home as energy efficient as possible, one of the best things you can do is properly insulate the walls of your home. 

Cavity wall insulation can stop heat from escaping through your walls, which in turn can reduce your energy bills considerably. This is done by drilling holes into your cavity wall, and then injecting insulation inside. 

This type of insulation only works if you have cavity walls though. More modern homes tend to have solid walls or come with walls that have already been fitted with insulation. If your home was built between the 1920s and the 1980s, there is a good chance you have cavity walls. Another sign of cavity walls is uniform, lengthways fitted brickwork (alternating long and short side placed bricks are a sign of no cavity). 

You can have a survey carried out on your walls to make sure cavity wall insulation would be suitable. If you’re eligible, then adding insulation could help significantly reduce both your heating bills and your carbon footprint. It will also make your home warmer. 

Not to mention that cavity wall insulation is one of the top eco home improvements, adding an average of £11,764 to the value of your property. 

You could spend anywhere from £650 and £6,100 to get cavity wall insulation. Prices include labour and materials. Keep in mind that the cost of labour rises in London and the South East, sometimes by as much as 20% more, on average. Find an insulation specialist in your area to get a more accurate quote on how much you might spend on cavity wall insulation.

Picture of a wall with cavity wall insulation being installled

What insulation is best for cavity walls?

Picture of insulation beads for a cavity wall

There are several methods of inserting insulation into cavity walls. If you aren’t sure which would be best for you, let us know what you’re thinking and the size and age of your home, and get some free quotes today. We recommend you ask for a few quotes before you settle on a tradesperson.


Type of cavity wall insulation  What is it? Pros Cons 
Expanding polystyrene granules or beads (EPS) Beads or granules of polystyrene that are inserted into the cavity. Eco-friendly and recyclable
Damp resistant
Easy to install 

Durable and lightweight 

Water resistant (prevents damp) 
Not good at insulating sound 

You need to clean the cavity before installation 

Can cause gaps in your cavity 
Polyurethane foam (PIR) A type of spray foam that expands as it sets. Incredibly efficient at insulating
Easy to install
Won’t cause mould 
Not environmentally friendly and can’t be recycled
More expensive than other options
Material shrinks over time 
Cavity wall boards Insulation boards that are fitted whilst the house is being built. Come in a range of sizes and different types of materials
An affordable option
Fire resistant and usually water resistant 
Hard to retrofit, so more suited for new builds
Less good at insulating than other options 
Wool fibre  Insulation made from sheep wool. Usually comes in rolls, like a blanket, or as loose fibre. Easy to install
Eco-friendly, renewable, and sustainable
Fire resistant
Good at protecting from moisture / damp + mould development 
More expensive than other options
Less thermal efficient than other options
Needs to be treated with chemicals to protect it from insects 
Mineral fibre Mineral fibres are molten rock that has been bound together and turned into sheets or loose fibres. Resistant to rot
Can be blown into the cavity, which makes it easy to install
Cheap to install
Environmentally friendly 
Cavity must be clean and spacious
Prone to clumping, which can cause damp
Repair is expensive  
Types of cavity wall insulation 

Most modern cavity wall insulations should last you up to 25 years. 

As well as cavity wall insulation, you should also consider getting loft insulation installed, as it is also a great way to cut your energy bills. Check out our loft insulation cost guide to find out more on how you can make your home even more energy efficient.

How much does cavity wall insulation cost?

Picture of a tradesperson installing cavity wall insulation from the outside of a home

How much you pay for your new cavity wall insulation will depend on the type of property you have, and its size. The bigger your home, the more expensive the total cost will be. Prices will also rise if you have a very old property, as additional remedial work may be needed. Damp also complicates things, as it will need to be dealt with before the insulation is installed.

To get a more accurate sense of how much your project will cost you, tell us what you’re looking for, and get some free quotes today.


Type of home Average cost 50m2Average cost 100m2Average cost 160m2
Semi-detached or detached home £1,150 – £2,500£1,600 – £3,200£,2,300 – £6,100
Flat  £650 – £1,800£1,200 – £1,900£2,000 – £5,000
Terraced home £700 – £2,000£1,300 – £2,000£2,200 £4,800
Bungalow  £750 – £2,200£1,400 – £3,800£2,400 – £5,500
Average cost of cavity wall insulation, according to property type and size

How much you end up spending will also be determined by the type of cavity wall insulation you get. For example, mineral fibre insulation for 50m2 would cost roughly £717, whilst 100mm PIR cavity boards for the same area would cost about £1,911. Similarly, you could pay £2,296 for mineral fibre on 160m2 or £6,116 for PIR boards. These prices will fluctuate depending on where you live in the UK. How difficult your cavity walls are to access can also affect costs. 

It takes between 1 and 4 hours to fully insulate cavity walls, depending on the type of property you have, and how big it is.

Can you do cavity wall insulation yourself?

Picture of a handyman insulating a wall cavity

We do not recommend you attempt to insulate your cavity walls yourself, as you will need a registered professional to complete the job. 

This is because the installation involves a difficult, technical procedure using hazardous products that need to be handled with care. Incorrectly installed insulation can cause damp or can lead to a less energy-efficient cavity wall too. 

Instead, hire a skilled tradesperson to do the job for you.


Can you get free cavity wall insulation? 

Under the Energy Company Obligation (ECO), a government energy scheme in Britain that seeks to tackle fuel poverty and reduce carbon emissions, a selection of British homeowners are eligible for a grant to help pay for the installation of insulation. 

You are eligible for this scheme if you claim one of these benefits (and also meet the income requirements): 

  • Child Benefit 
  • Pension Guarantee Credit 
  • Income-related Employment and Support Allowance (ESA) 
  • Income-based Jobseeker’s Allowance (JSA) 
  • Income Support 
  • Tax Credits (Child Tax Credits and Working Tax Credits) 
  • Universal Credit 
  • Housing benefit 
  • Pension credit saving credit 

You must own your own house or have your landlord’s permission to benefit from ECO. You can access more advice on energy saving schemes here

How much energy does cavity wall insulation save? 

Picture of a person calculating heat loss of home with a calculator

The good thing about cavity insulation is that within just a few years it will pay you back for the upfront installation costs, by saving you money on your energy bills. 

This is because insulation can help trap up to a third of your home’s heat which would otherwise escape through your walls. 

The below prices refer to the average UK homeowner’s annual energy bill savings, as a result of having installed cavity wall insulation. 

 Detached home Semi-detached home  Flat Mid-terraced home Bungalow  
Yearly energy bill savings   £480  £285  £145  £180  £195 
How much cavity wall insulation could save you in energy bills, yearly, according to the Energy Saving Trust 

As well as this, depending on the type of property you have, you could save between 335 – 1100 kg of CO2 a year by inserting cavity wall insulation, helping to significantly reduce your carbon footprint. 

How much does it cost to have cavity wall insulation removed? 

Picture of tradespeople removing cavity wall insulation

There are a few reasons why you might want to get rid of the current insulation in your cavity walls. This process is completed either by sucking out the insulation using a vacuum or breaking up the insulation into smaller pieces using a specialist machine. 

You might want to have your cavity wall insulation removed if: 

  1. Older insulation methods are potentially toxic and could have carcinogenic health implications. 
  1. Occasionally, DIY or unprofessional installers install insulation that is not suitable for the property (for instance in timber framed properties). Equally, poorly installed insulation with gaps in it can lead to dampness. If your insulation develops damp, it will need to be removed. Always make sure you hire professional installers. You can do so here.


  1. If your home suffers from a flood or fire, this could cause damage to your insulation, which will need replacing. 

How much you spend on removing your cavity wall insulation will depend on the scope of the project. You can expect to pay roughly between £20 – £22 per m2 for cavity wall insulation removal. For a whole house, that could look anywhere between £1,600 – £2,600. 

What are the building regulations for cavity walls? 

All cavity wall insulation requires a building notice submitted to a building control body. 

Building regulations are required to ensure that your chosen insulation material is suitable for your property. 

Most local authorities will not levy a building control charge. For more information, access the Planning Portal website

What is the U value of cavity wall insulation? 

The U value, also known as thermal transmittance, measures the rate of heat loss of a fabric. 

The equation for the U value looks like this: 

Picture of cavity wall insulation equation

R represents thermal resistance (of your cavity wall insulation). The U value is measured in Watts-Per-Metre-Square-Kelvin (W/m2K). 

Building regulations will check your U value to make sure your insulation complies with the required amount. The lower your value, the better. Building regulations require your cavity walls to be no less than 0.18 (W/m2K). 

A skilled tradesperson will make sure your insulation conforms to all building regulations. You can hire an insulator here.



Picture of the outside of a home having cavity wall insulation installed to an extension

Cavity wall insulation is one of the most effective ways to stop heat escaping from your home, reducing your energy bills and carbon footprint. It’s no surprise that it’s currently a top eco home improvement, as properly insulated walls can add over £11,000 to the value of your home. 

Your insulator will be able to advise you on what type of insulation you should get, according to the age and layout of your home. How much you end up spending will mostly depend on the size of your property. 

For a more accurate quote on the total cost of adding cavity wall insulation to your home, let us know what you’re thinking, and get some free quotes today.


*The Rated People cost guides are produced in collaboration with the quote-building platform PriceBuilder, and a range of tradespeople across the 30+ trades on our platform were consulted. Please note that the prices included are for guidance only – how much you end up spending will depend on the specific requirements of your project.

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