Cavity wall insulation can be a hard topic to get to grips with, and knowing whether or not your home will benefit from it is something you need to fully understand before undertaking any work.
It’s estimated that as much as 35% of heat loss from homes is due to walls that have no insulation – meaning that if you opt to install cavity wall insulation, you can increase your home’s energy performance and save money on your annual bills.
In this article, we’ll be helping you to:
- Understand how much cavity wall insulation costs
- What affects the cost of adding cavity wall insulation
- How to save money on cavity wall insulation for your home
- What’s involved in adding cavity wall insulation to your home
- How to find and hire a professional.
Keep reading to find out everything you need to know about cavity wall insulation.
How Much Does Cavity Wall Insulation Cost?
The costs for cavity wall insulation will vary depending on the size of your house, as well as the insulating material your contractor deems appropriate for your home. Below are typical costs for installing cavity wall insulation in different types of houses:
| HOUSE TYPE | ESTIMATED INSTALLATION COST | POTENTIAL SAVINGS |
|---|---|---|
| Detached bungalow | £750 to £800 | Up to £110 per year |
| Flat | £400 to £450 | Up to £85 per year |
| Mid-terrace house | £600 to £650 | Up to £105 per year |
| Semi-detached house | £1,000 to £1,200 | Up to £165 per year |
| Detached house | £1,800 to £2,000 | Up to £280 per year |
Prices last reviewed in November 2022.
For a detached bungalow, the estimated installation cost will be between £750 to £800, and the potential savings in energy bills will be up to £110 per year.
A flat will cost between £400 to £450 to have cavity wall insulation installed, and can potentially save you up to £85 in bills per year.
Moving up the size scale, a mid-terrace house will cost between £600 to £650 for installation, and could save you up to £105 per year in heating bills.
A semi-detached house will be between £1,000 to £1,200 to have cavity wall insulation installed, saving you up to £165 per year.
Finally, a detached home can cost anywhere between £1,800 to £2,000 for cavity wall insulation and can save you up to a potential £280 per year on heating bills.
These figures will vary depending on where you live in the UK, and there may be grants available that may cover the entire cost of the insulation or a significant portion of it. The estimated energy bill savings per year have been taken from the Energy Savings Trust.
As a general guide, cavity wall insulation costs around £200 to £250 per two-storey wall, and it’ll take the labourers around two hours per wall to install the insulation.
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What Affects the Cost of Adding Cavity Wall Insulation?
As you’d expect, there are some areas of cavity wall insulation that are non-negotiable, and will drive your price up or down – and there’s nothing you can do about it. However, as we’ll discuss, there are ways of being financially savvy that can help to bring your overall project costs down.
Size of Your Home
As you can see from the table above, the size of your home will have a direct impact on the price you will be expected to pay for cavity wall insulation.
With it costing between £200 to £250 per two-storey wall, you can quickly tot up how much your home might cost based on the space you have – but, as mentioned above, this can all be offset by the potential heating bill savings you’ll pick up year after year, so it can result in a cost-neutral situation when installed correctly and used effectively.
Type of Insulation
There are different types of thermal insulation to choose from, all with different price tags. Wool fibre is the most expensive at between £25 to £30 per metre squared; while mineral fibre is between £13 to £18 for the same size.
Survey Costs
This is another inescapable cost – unless you want to run the risk of not having it done, and then having to pay up when it’s time to get the insulation taken out as it’s causing your home damp problems.
The cost of your wall survey won’t be included in the cost of installation or supplies, and will usually add another £75 to your bill. It is an essential part of the project, and not something you should skip to save a bit of extra cash.
How Can I Save Money on Cavity Wall Insulation for My Home?
Comparing quotes is a great way to potentially reduce the cost of cavity wall insulation. HouseholdQuotes can help you get quotes from multiple cavity wall fitters near you, so that you can find someone that suits your budget.
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There are some great ways to make cavity wall insulation that bit cheaper – you just need to be savvy about your choices during your project planning stage.
Finding out if you actually need cavity wall insulation is the number one cost saver – as it may well turn out that your walls aren’t suitable for it, and so having it fitted would be a complete waste of money.
Generally speaking, walls that are constantly exposed to the elements (sea-facing particularly) won’t be great candidates for cavity wall insulation as it may result in damp problems – which will inevitably cost you a lot more than the cost of installation to put right.
If you have the means to pay for the insulation right now, and it’s suitable for your property, then do so – the sooner you do, the sooner you’ll be reaping the benefits of having a better-insulated home, protected from the cold outdoors.
As shown above, you can look to save hundreds in your annual energy bill, which can, over time, make your installation cost-neutral.
We know by now that local companies will charge less than nationals, as they have little to no overheads to cover. While you might have to wait a little longer for the local company to have space in their books, what you lose in expediency you’ll gain in money, which is useful when embarking on potentially costly projects.
How Do I Know If Cavity Wall Insulation Is Right For Me?
Cavity wall insulation can be brilliant and help you reduce your bills, but it may not be the right choice for every home. Let’s take a look at the key advantages and disadvantages of having it installed.
| ADVANTAGES | DISADVANTAGES |
|---|---|
| When fitted in properties where thermal benefits will be effective, you can save money on your energy bills | Some homes aren’t suitable for cavity wall insulation, and can cause damp problems over time |
| Reduces heat loss | Unscrupulous traders are taking advantage of government funding for cavity wall insulation, so you need to perform background checks before agreeing to work with someone |
| Helps to make your home cheaper to heat in the colder months | Surveys are required before cavity wall insulation is fitted, which comes at an extra cost |
Cavity wall insulation has the potential to save you money on your energy bills, if fitted in walls where the thermal benefits will be effective. Here are some projected savings over a year and the payback period for the different types of houses typical in the UK:
- For a detached house that costs between £1,800 to £2,000 to insulate, you can potentially see a saving of £280 per year giving a payback period of around three years
- If you spend between £1,000 to £1,200 in insulating your semi-detached house, you should notice £165 in savings which is a payback of three to four years
- Insulating a mid-terrace house by spending £600 to £650 should give you your money back in three to four years and save you £105 per year
- For a bungalow and mid-floor flat, you will enjoy savings of £110 and £85, respectively, both having a payback period of under five years
Given the payback figures above and the savings you can get from just this simple energy efficiency measure, cavity wall insulation is well worth the investment. However, numerous unscrupulous traders are taking advantage of government funding for cavity wall insulation, you should only hire cavity wall installers who are registered with a trade body like the Cavity Installation Guarantee Agency (CIGA), National Insulation Association (NIA), or the British Board of Agrément (BBA).
Looking next at the disadvantages, some homes (or parts of a home) may not be suitable for cavity wall insulation. Some homeowners report damp problems soon after they have had cavity wall insulation – in the majority of cases, damp problems are missed during the pre-installation inspection or the insulation has been poorly installed, or installed in unsuitable walls.
A professional cavity insulation contractor should advise you on whether your walls are suitable or not. Taking the steps above should help prevent damp issues from arising after cavity wall insulation.
What’s Involved in Adding Cavity Wall Insulation?
Cavity wall insulation is the process of filling the cavity with an insulating material, commonly foam, which is pumped into the cavity through holes drilled in the external wall. Other insulating materials include mineral wool and polystyrene beads.
Homebuilding practices in use in the past have double walls, an inner wall, and an outer wall, with a cavity between them. The thinking behind the cavity is to prevent rain from penetrating through the wall.
However, unfilled cavities will let heat travel from the inside to the outside, placing increased demand on your heating system.
How Do I Find and Hire a Professional?
Finding the right cavity wall insulation specialist can be challenging. At HouseholdQuotes, we can connect you to traders in your area.
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Choosing an installer who is a member of a recognised trade body is critical in obtaining a good and guaranteed cavity wall insulation service.
The top three trade organisations for the insulation industry are:
- National Insulation Association (NIA)
- Cavity Insulation Guarantee Agency (CIGA)
- British Board of Agrément (BBA)
Seeking out referrals from friends, family and neighbours can be a great way to go to ensure a good service has been had recently – else it’s a name to strike off your list of potential traders!
If you want to keep your online search consolidated and as easy as possible to navigate, using HouseholdQuotes can help to save you up to 40% on your project fee by allowing you to directly compare contractors with one another, without the need to ever leave the website.
Ensuring the Professional Is the Right Fit
Your trader must check your walls first to make sure they’re eligible for cavity wall insulation. Without this step, you could end up having it fitted just to have it ripped out again after a few years of wet weather causing you damp problems.
You should always seek a written quote to save yourself from any nasty financial add-ons at the end of the project, and always remember to refuse to work with someone if they won’t give you written confirmation of terms.
Seeking out their experience, as well as past references and photos or videos of their older jobs will help you to see if their work is of a standard you want. If you’re going on a word-of-mouth referral, speak to them and find out what the traders are like day-to-day at the property, as you want to make sure they’re a good match for you as they’ll be in your home for a little while.
Finally, checking to make sure they have insurance in place will save you from anything falling on your lap in terms of liability if something goes wrong during the job.
Final Checklist
Cavity wall insulation can help to cut down your annual energy bills, keep your home warmer for longer and block out unwanted noise. However, there are a few crucial components to be made aware of when looking at cavity wall insulation, so before you get started on your project, here’s what we suggest:
- Get a survey completed to see if your walls are eligible for cavity insulation
- Make sure the walls in question haven’t been subject to damp problems in the past, as this can render them ineligible for cavity wall insulation
- Find a credible trader who is a member of a recognised trade body to make sure you have a reputable trader working for you
- Get a written quote to make sure there are no nasty surprises at the end of the job
- Make sure they have insurance in place
- Enjoy the savings in your energy bills for years to come!
Use HouseholdQuotes to find local cavity wall insulation installers and potentially save money on your cavity wall insulation.
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Frequently Asked Questions
How Long Does Cavity Wall Insulation Last?
If properly installed and in an eligible wall, cavity wall insulation should be able to last for the lifetime of the building, as it is built for life. The Cavity Insulation Guarantee Agency (CIGA), however, runs for 25 years.
Does Cavity Wall Insulation Reduce Noise?
Cavity wall insulation can reduce noise – you can also have soundproofing put in place to muffle sound further.
Can Cavity Wall Insulation Cause Damp?
Damp after cavity wall installation is a tell-tale sign that your walls weren’t eligible for it in the first place. If you experience damp problems on a wall that is exposed to the elements, likely, it won’t be a great candidate for cavity wall insulation as it’ll just soak up the moisture and trap it between your walls.
To prevent any damp issues, try to keep the following in mind:
- Resolve any pre-existing moisture problems before adding cavity wall insulation
- During the survey, check the integrity of the outer walls to ensure there are no cracks in the render or poorly laid brickwork
- Don’t add cavity wall insulation to any walls prone to driving rain, as they are likely to get wet
Can All Houses Have Cavity Wall Insulation?
No – it’s always best to have a survey done on your walls beforehand to make sure you are eligible. You’ll need no cavity wall insulation, at least a 50mm wide gap between your walls, and not have experienced damp problems before.
In particular, you should not add cavity wall insulation to any walls which are exposed to the elements, especially wind-driven rain – filling the walls persistently exposed to driving rain may result in damp problems, especially if mineral wool is used and it gets wet.
Are There Any Government Grants for Cavity Wall Insulation?
There are government grants available for eligible households, subject to usual caveats about meeting the eligibility criteria.
As we’ve mentioned earlier, this is why it’s important to have a reputable trader complete your work, else they’ll just fit the cavity wall insulation anyway to reap the rewards of this scheme, which doesn’t have you or your home’s best interests at heart – especially if your walls aren’t even eligible for insulation, which may result in it costing you an awful lot more than originally anticipated.
Which Type of Insulation Is Best for Cavity Walls?
It’s essential that you have a survey conducted first before having cavity wall insulation installed. Whilst you should have everything checked by a professional surveyor, here are some general factors which can help you determine whether your home is suitable (or unsuitable) for cavity wall insulation:
- Your property’s walls are empty cavity walls
- Your cavity is at least 50mm wide
- The masonry or brickwork of your home is in good condition and not crumbling
- It is more than 10 years old, as most newer houses will have insulation already
- The walls are not exposed to driving rain, and you are not experiencing damp problems
The most common material is polystyrene beads, although there is foam available, too. If you are under any doubts, ask your cavity wall insulation installer who will be able to advise you further.
Can Cavity Wall Insulation Keep My Home Cooler in the Summer?
Yes – although the main concept of insulation is to keep heat in and to keep your home warmer in the cooler months, cavity wall insulation can also help to keep your home cooler in the summer months as the warm air from outside cannot travel through your bricks as freely.
How Much Does Loft Insulation Cost?
As the warmth from our heating systems rises, it escapes through the roof – but loft insulation has the power to retain this heat, slashing heating bills significantly.
If you live in a terraced house, your cost of loft insulation can range from £125 to £1,720, while for those in terraced homes, these prices can rise to £300 to £4,125. For full information on loft insulation prices, take a look at our dedicated page.
Does the Government Offer Any Grants for Solid Wall Insulation?
Most homes built before 1920 – and some after – have solid walls, and they’re notoriously bad at retaining heat; in fact, energy escapes at almost twice the rate of cavity-walled homes.
The good news is that solid wall insulation grants are available to help install external and internal insulation. To qualify, you must be on certain benefits, and at least 50% of your exterior walls must be solid and uninsulated.
For more information, take a look at our dedicated page on solid wall grants.
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