Cavity Wall Insulation – Prices, Damp Issues and Some Great Advice

Cavity wall insulation is one of the cheapest ways to improve the thermal efficiency of your home.

The material is cheap and quick to install, it should last forever and you’ll notice a drop in your heating bills.

Unfortunately, some homeowners have experienced serious issues with their cavity wall installations, including:

  • Damp patches on walls.
  • Odours and smells.
  • Bad air quality in the home.
  • Hefty bills to remove the insulation.
  • Increased heating bills.

Jeff Howell, a popular Telegraph writer stated that in his opinion, cavity wall insulation could be the next PPI scandal.

More recently, an entirely new industry of cavity wall insulation removers has appeared and guess what? It costs more to remove this stuff than it does to install it.

No surprise there.

While many thousands of installations have been completed without issue, we recommend researching the potential damage cavity wall insulation could do to your home.

Not every property is a good candidate for this type of insulation.

Researching cavity wall damp would be a good place to start.

We’ve also published some crucial information you’ll find located further down on this page, we think it should help you make the right choice.

Our Guide to Cavity Wall Insulation and Prices

We initially created this page as a price guide so consumers could get an idea of how much it costs to install cavity wall insulation (jump to that section if you’re in a hurry).

During our research, we came across hundreds of complaints regarding botched projects, damp, mould and even increased heating bills.

The discovery certainly piqued our interest.

What was going on in this industry and how can consumers make the right choice so they can protect their homes?

We hope you find our guide helpful, this page was last updated on the .

What You (Should) Get For Your Money

Here is a list of everything you should get when you choose to have this insulation inserted into the cavity:

  • A full inspection of the property, it may already have cavity wall insulation or it may not be suitable for this type of work (more about that later).
  • The installers will drill 20mm holes along every metre throughout the wall.
  • The insulating material will then be blown into the cavity, a pressure gauge will tell the installer when the wall is full.
  • All holes will be filled with cement.
  • A certificate or letter confirming the work has been completed will then be issued.

cavity wall being filled

Not Every House is Suitable for Cavity Wall Insulation

This is where the problems arise.

According to the UK government, around 55,000 consumers experience botched cavity wall installations each year.

The vast majority of these are because of the following three reasons:

Concrete Gutters – These gutters are placed directly above the cavity and are prone to leaking. If rainwater soaks the insulation, damp problems will arise. It’s vital that any concrete gutters are first lined with either a rubber or aluminium product prior to the installation of this insulation.

Wind Driven Rain – This is a common problem. If your property is located in an exposed location that experiences wind-driven rain, the water will soak through the bricks and saturate the insulation. It can take months for wet insulation to dry out and dehumidifiers are often needed.

Non-Standard Wall Construction – Some walls don’t have any cavity at all (called solid walls), while some have a cavity that’s made from alternating brick patterns which may prevent an installer from injecting the insulation fully.

The issue of cavity wall insulation damp has been around for years.

In 2011, the consumer protection service released this statement:

In early 2011 Which? uncovered some bad practices when it came to getting advice about cavity-wall insulation for a house prone to damp problems.

What Happens if the Insulation Gets Wet?

Wet cavity wall insulation is a major problem that often leads to:

  • Wet internal and external walls.
  • Damp patches.
  • Mould and unhealthy air.
  • Wet walls are cold walls, so your heating bills may go up – the exact opposite of what you were expecting.

It can take a long time for the insulation to dry out, by which time the plaster on the walls may be ruined.

In addition to the cost of redecorating, you can also expect to incur a fee to remove the insulation.

Consider This…

We have also heard of reports of homeowners installing this insulation in the spring or summer and not experiencing any damp problems until the winter.

We know of two consumers that have then paid out thousands of pounds for unnecessary rising damp treatments, costly air dehumidifiers and redecorating BEFORE realising the damp was actually caused by the insulation.

Many damp proof specialists are unaware of how common insulation damp is and simply misdiagnose the cause as rising damp.

Your Next Step

The truth is that 98-99% of installations are trouble-free, but doing your homework first only takes a few minutes and could save you a lot of problems in the future.

Below you’ll find our cost guide for cavity wall insulation and at the base of this page, you can get your own quote.

But first, we suggest you determine if your property is a good candidate for cavity wall insulation.

The map below highlights areas where wind-driven rain is common.

Think long and hard before installing this insulation if you live in one of the areas marked as “very severe”.

We also suggest you try to answer some questions:

  • Is the property on a hill that experiences wind-driven rain?
  • Does the property have concrete gutters? What condition are they in?
  • What condition is the wall in? Is the mortar pointing in good condition or are there gaps that could let water in?
  • Have any of my neighbours had issues with cavity wall insulation?

Cavity Wall Insulation Cost

As part of our research, we contacted 23 cavity wall insulators and requested a price to fill our cavity with insulation.

The property is a typical 3-bed semi detached house with 3 external walls.

While the prices aren’t a guarantee of what you’ll be charged (get your own price here) they are an average of the figures we were given:

LocationSmall Business /TraderLarger Business (5+ employees)
Need a Custom Price? >Compare Up To 3 Personlised Quotes Here
London AreaN/A£500.00
South, SW and MidlandsN/A£500.00
Outer Region and NorthN/A£475.00




How to Get a Hefty Discount

Many utility suppliers now offer free or discounted loft and cavity wall insulation.

These discounts are often based on where you live, the type of property you live in and also whether you receive certain benefits.

Local councils occasionally offer financial incentives to have wall insulation, so check your council’s website and for any offers.

Expected Cost Savings

Approximately 1/3 of heat loss in an uninsulated home will be through the walls.

According to the Energy Saving Trust, the following savings can be achieved per year:

Detached Property – £275.00

Semi Detached – £160.00

Terraced – £105.00

Flat – £90.00

The statistics are based on a typical 3-bed home with gas central heating.

Get a Cavity Wall Insulation Price Today

We hope you found our research into cavity wall insulation helpful, informative and not too negative!

The truth is that the vast majority of installations go without a hitch, you just need to take a few extra steps to make sure you’re not the 1% of folks that experience problems.

If you would like to start comparing prices for cavity wall insulation, just tap the button below:

  • Submit details about your property
  • Read reviews from previous but recent customers
  • Get a written quote in a timely manner
  • Leave your own feedback when the project is complete
Click Here to Get Your Free Competitive Quotes

Not ready to get quotes? See all of our cost guides here

5 Responses to “Cavity Wall Insulation – Prices, Damp Issues and Some Great Advice”

  1. myrooffOctober 4, 2016 at 4:46 pm #

    Thanks but what about the cost of insulation?

  2. Gordon FisherNovember 23, 2016 at 3:25 pm #

    Hi there

    I would like to know the cost of cavity wall insulation for a linked bungalow, 3 bedrooms, 6 rooms altogether and a conservatory which is not heated as yet.

    Thank you

  3. john kissaneDecember 11, 2016 at 8:44 pm #

    I would like to know the cost of cavity wall insulation to one wall of a flat about 2.5 metres by 2.5 metres

    • Colin MoullDecember 18, 2016 at 6:42 am #

      You could try Wallrock Thermal Liner 10m x 75cm supplied by toolstation (free delivery), its applied a bit like wallpaper but insulates and leaves a robust surface to decorate as an alternative to cavity wall insulation.

      I think you’ll find most insulation firms will not want to tackle such a small job.

  4. Des ShillingfordDecember 29, 2016 at 8:51 am #

    Need cavity insulation in extension

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