The average cost of cavity wall insulation
starts from £1,000 to over £3,000
Pricing guides

How much does cavity wall insulation cost?

If you’re looking for a cavity wall insulation quote, keep reading. Our cavity wall insulation cost guide covers various job sizes, materials and considerations, helping you to accurately gather pricing information before contacting a professional. Note that all estimates and cavity wall insulation costs are accurate as of 2024.

As you search for a reliable cavity wall insulation installer for your property, getting an idea of associated costs based on recent, applicable data is a must. The better prepared you are for the expense of hiring a professional, the sooner you can budget effectively and make sure that you get the high-quality service you need for your home.


Average cavity wall insulation costs

Every home in the UK has either solid walls or cavity walls. Since 1982, UK properties have been required by law to include certain minimum insulation levels. This includes cavity wall insulation, where applicable. However, if your home was built between 1924 and 1982, there’s a distinct possibility that the spaces in your walls have never been filled. 

In older properties, retrofitting cavity wall insulation is a relatively affordable way to increase the cosiness of your home by up to 33%. Doing so can also reduce your home’s CO2 emissions, improve your EPC (Energy Performance Certificate) rating and could lower your annual heating costs.

But how much does cavity wall insulation cost in the UK, from materials to installation? It’s not necessarily a straightforward answer. For instance, the cavity wall insulation cost for a 3-bed semi in its entirety might be very different from the cavity wall insulation cost for a bungalow wall. 

Many factors will go into your final quote from a contractor, but as a jumping-off point for further research, here’s an overview of the averages for some project types commonly undertaken by cavity wall insulation specialists

Cavity wall insulation projectAverage price 
Cavity wall insulation for a detached property£3,200 
Cavity wall insulation for a semi-detached property£2,700
Cavity wall insulation for a mid-terrace house£1,800
Cavity wall insulation for a bungalow£2,400
Cavity wall insulation for a flat£950

Get a free insulation quote

We can help you meet professional insulation specialists near you to get real quotes today.

Cavity wall insulation cost breakdown


How much does cavity wall insulation cost?

The price of this kind of job isn’t set in stone, making it challenging to predict how much you’ll pay for cavity wall insulation without knowledge of your project specifics. 

Across the board, though, hiring a tradesperson will be more expensive than attempting a DIY job. But, since incorrectly installed cavity wall insulation can cause damp and mould issues that could threaten the structure of your home, it’s worth footing the bill. A cavity wall insulation specialist will be able to complete the work to a high standard and comply with all the latest Building Regulations for the UK.

When you hire a cavity wall insulation specialist, the two most significant costs to account for in your budgeting phase are labour and materials. Labour usually equates to an hourly rate of around £15. Regarding materials, cavity wall cost per m2 is from £30 to £65, depending on the substance used to fill the cavity. Polyurethane foam, for example, has a higher price point than mineral wool. 

The bigger the project in terms of scope and area, the more you’ll pay for both of the above. Other cost-increasing factors include:

  • The need for a pre-installation survey to determine suitability and condition 
  • The expense of any additional repairs flagged by the pre-installation survey
  • Potential removal/extraction expenses associated with existing cavity insulation

Regardless of the size of your project, you’ll find that costs are generally recouped in energy savings within five years of installation. Plus, funding support for cavity wall insulation is available to qualifying households, so you may be eligible for a government-backed grant that makes this process less costly than initially anticipated.  

Cost of cavity wall insulation surveys and inspections

Only some properties are of a suitable style or in proper condition for cavity wall insulation, even within houses built before 1982. Before you get to work on an installation, you’ll need an initial survey conducted of your home. 

During this survey, a professional will inspect the property, discuss your plans and explain the process. Together, you’ll determine appropriate methods and materials to use. You’re likely a good candidate for the installation of cavity wall insulation if: 

  • As mentioned above, your home was built between 1924 and 1982
  • Your wall cavities are at least two inches wide 
  • Your brickwork or masonry is in good condition
  • Your walls are dry, with no signs of damp on the interior or exterior
  • Your ventilation is adequate or there’s potential to fit a vent successfully
  • Your external walls are accessible to installers

Many of your local insulation specialists will add the survey cost onto the total quote for your project, and where itemised, it costs an average of £75.

If you already have cavity wall insulation and you’re looking to hire a specialist to determine whether it might need replacing, you’ll need to account for cavity wall inspection costs. Options available include thermal imaging, visual inspection of suspected areas of cracking or movement, use of detection apparatus, precision drilling and camera-assisted borescope analysis. A thorough cavity wall insulation inspection could cost up to £350.

Cost to make additional repairs

Starting one big job in the home can reveal other issues that need resolving. Whether your installer has spotted something that needs to be fixed during an insulation inspection or noticed a problem in their initial home survey pre-installation, you may get a larger bill than you budgeted for.

One common issue that might mean additional repairs is related to wall tie failure. Wall ties connect the two leaves of a cavity wall, and when they don’t function properly, there is a risk of total wall collapse and severe structural damage to your home. Since wall ties are usually unseen, it can be hard to spot external signs that they are failing until a closer inspection is carried out. 

If your installer spots signs of imminent wall tie failure, you’ll need to get these ties repaired or replaced before you can tackle replacing or adding cavity wall insulation. Cavity wall tie replacement costs could be anywhere from about £1,000 to £2,000, depending on the wall size and the amount of damage present.


Cost of removing cavity wall insulation

There are various reasons that you may need to remove and replace your cavity wall insulation, including the following: 

  • Damp and mould issues
  • Performance issues
  • Degrading insulation materials
  • Incorrect initial installation
  • Vermin problems

Luckily, extracting cavity wall insulation isn’t as complex as you might expect. Using compressed air and an industrial vacuum, your wall cavity can be thoroughly cleared and prepared for a fresh installation for an average cost of £21.50 per m2, or £2,100 for a whole house. The latter cavity wall insulation removal cost estimate is based on an average-sized property, so if your home is smaller than average, your quote may be closer to £1,600 or thereabouts.


Cost of insulation materials

As discussed above, the materials used to insulate your cavity walls will affect project costs to a significant degree. The best insulation material for your job and budget will usually be recommended by your installer, a specialist in this area with valuable experience to draw on. Different materials provide different quality standards and benefits, with price points breaking down as follows:

  • The mineral wool (either glass or rock) blown cavity wall insulation cost per m2 is usually from £13 to £18
  • The expanded polystyrene bead cavity wall insulation cost per m2 is usually from £18 to £22
  • The polyurethane foam cavity wall insulation cost per m2 is usually from £22 to £26


Cost of additional insulation services

If you’re interested in adding cavity wall insulation to a property, you may well be facing other insulation deficiencies that affect the energy performance and warmth of your home, too. Most expert insulation installers will also recommend looking at your roof insulation if you haven’t already, as this can hugely impact your home’s efficiency and EPC rating. The cost of roof insulation is determined by:

  • The scope of the project and size of the space to be insulated
  • The type of roof insulation to be used in that space
  • The hourly/daily labour rates of the installers you choose to work with
  • The availability of government funding support
  • The existing situation with your loft or roof and whether any other work is needed

The average cost of roof insulation installation in the UK is from £400 to £600, but exploring even one of the above factors more thoroughly will show how subject to change these figures are. Looking purely at material costs, for example:

  • The cost per m2 for glass wool insulation is usually from £4 to £6
  • The cost per m2 for rock wool insulation is usually from £5 to £9
  • The cost per m2 for warm deck insulation boarding is usually from £15 to £20
  • The cost per m2 for spray foam insulation is usually from £20 to £30

How long does cavity wall insulation installation take?

The time required for cavity wall insulation to be professionally installed depends primarily on the size of your property and project and the accessibility of your exterior walls. In usual circumstances, in the hands of an experienced installer, it shouldn’t take longer than a couple of hours. Along with the factors previously listed, the relatively quick and easy process may be affected by:

  • The number of professionals assigned to the job, e.g., a team of two, three or four 
  • Whether installation will be preceded by the removal of old insulation or repair of other wall issues, which will increase the total working time
  • The material your specialist is working with and the associated ease of supply and installatio


How to reduce cavity wall insulation costs

When working with the structural elements of a home, we find our customers want to balance professional, trustworthy support with affordable, value-for-money options. They want to save where they can without sacrificing on quality or care. If you’re in this boat, hoping to reduce the total cost of cavity wall insulation, there are several routes that you might like to take.

  • Changing your chosen insulation material: If you’ve opted for polyurethane foam insulation, you may be able to reduce your quote by selecting a lower-budget option instead. Swapping foam for polystyrene beads could save you up to £8 per m2, and changing foam out for mineral wool could save you up to £16 per m2. These cost cuts add up, especially over larger-scale whole-house projects. 
  • Comparing and contrasting like-for-like quotes from local installers: After using MyBuilder to share your job for free, you can reach out to multiple available installers in your area for a full, all-inclusive quote. You can then compare the quotes you gather to get the best deal. This will lead you to a final hiring decision that suits your budget but made with a good understanding of your chosen installer from reading customer reviews and professional histories.
  • Looking into government funding support: As mentioned, certain households and individuals will be eligible for government-backed schemes that seek to reduce carbon emissions, support homeowners and tenants and improve the efficiency of UK properties. It’s worth looking into your options in this area, especially if you’re currently receiving income benefits or living in a home with a low EPC rating and high carbon emissions.
  • Taking a long-term approach to the expense: Though not strictly a way to reduce the cost, looking at your cavity wall insulation as a long-term investment might help you better contextualise what you’ll be paying for. Once you have cavity wall insulation, you’ll save around £400 on average on your energy bills each year. If you spend £2,000 on the insulation installation, the cost will have paid itself off in five years.



Can I DIY cavity wall insulation?

Much as we love to save money when working on our homes, a DIY approach isn’t recommended for cavity wall insulation. Connecting with an experienced specialist is your safest bet. A team of installers should be able to complete the job and remove any resulting mess for you in a few hours. Meanwhile, doing it yourself could mean voiding your property insurance and missing structural issues in need of rectification that only a professional would have spotted.

Which cavity wall insulation material should I choose?

It all depends on your budget. The three cavity insulation options available to you vary in price and efficiency Polyurethane foam is the most expensive option but also the most effective, with a lambda value of 0.030 W/mK (the lower the option’s lambda value, the less heat will escape from your home). Mineral wool lambda values range from 0.034 to 0.040. Polystyrene bead insulation is a middle ground between the two in terms of price and performance, with a lambda value of 0.034. 

What should I look for when hiring a cavity wall insulation specialist?

Cavity wall insulation installers don’t legally need a particular qualification or certification. That said, many will have pursued an NVQ or similar to evidence their knowledge and expertise to customers. The best things to look for when hiring a cavity wall insulation specialist are relevant experience with projects like yours and a strong track record, both of which you should be able to find by browsing an installer’s MyBuilder profile and checking out their verified reviews from past customers. 


Your cavity wall insulation checklist

If you’re unsure how to find and hire an insulation installer, this simple checklist should set you on the right path. Follow the five steps below, and you’ll soon find the perfect cavity wall insulation specialist for your needs.

Do some independent research – Do some initial research to understand the insulation options available, from wool to foam. Then, begin to shape your budget, looking into costs and averages so that you know what to expect from installers’ quotes.

Confirm your budget with a cavity wall insulation cost calculator – By inputting your wall measurements into an online cavity wall insulation calculator, you’ll get a more accurate initial price estimate than is possible from looking at the averages. 

Find installers with relevant experience and positive reviews – MyBuilder makes this simple, but however you source potential hires, don’t waste time on a tradesperson with bad reviews or no experience working with cavity walls. Get the expertise you’re paying for.

Ask for comprehensive quotes from multiple professionals – Gather a full breakdown of costs, including things like debris removal and initial surveying, from each installer you speak with. Compare these to feel reassured that you’ll be paying a fair price as well as the price that best suits your budget.

Never make payment in full before the job is complete – Most tradespeople will request a deposit in advance of installation and payment of the remainder once the job is done. An out-of-the-ordinary payment request could indicate bad intentions or cash flow issues.

Looking for a reliable cavity wall insulation specialist local to you? Post your job for free on MyBuilder, and we’ll help you find your perfect tradesperson match. 


Get a free insulation quote

We can help you meet professional insulation specialists near you to get real quotes today.

Loft insulation costs

Loft insulation costs

How much does loft insulation cost?

Roof insulation costs

Roof insulation costs

How much does roof insulation cost?

Insulation costs

Insulation costs

How much does insulation cost?

View more pricing guides