Problems caused by Cavity Wall Insulation can be harder to spot than you might think

 Even for those people who keep a close eye on problems caused by retro-fit cavity wall insulation, and who are aware that adding modern insulation to older houses can find the issues surrounding cavity wall insulation confusing to say the least seeing we are not builders or construction experts.

There are many different ways that cavity wall insulation problems can occur in your house, and this can make it difficult to attribute the problems to cavity wall insulation failure.

There can be many problems caused by cavity wall insulation and adding insulation to a cavity wall can cause rain water to penetrate the inner wall in many ways such as spalled brickwork or bad pointing or cracked bricks or render, resulting in a damp house potentially top to bottom. However, it is also true that there are many more kinds of problems caused by cavity wall insulation than rain penetration.

Rain water doesn’t need to penetrate the inner wall to cause cavity wall insulation problems. It is possible for your house to become damp in a few different ways due to various cavity wall insulation problems.

Problems with Cavity Wall Insulation are not always caused by rain penetration!

Even when insulation is not affected by rain penetration from the outer wall because the outer wall bricks and mortar are in excellent condition, filling your cavity wall with insulation of any kind can result in damp if the insulation is installed where full and proper pre-checks and treatment where required are not carried out prior to install, and ultimately cause a colder house due to wet cavity wall insulation problems. This can mean your boiler is turned up and heat is being drained out of your wet walls quicker than it is heating your house.

One of the ways you may experience problems with cavity wall insulation, is that your house can become damp caused by cold spots. When cavity wall insulation is poorly installed, gaps can be left in the insulation, creating cold spots. This is a big cause of problems with cavity wall insulation. The insulation in your cavity wall warms the house up, which is great in theory, but in the places where there are cold spots, this condenses more quickly because of the warmer air. This condensation has nowhere to run off, and so festers, hot air and cold air meet meaning more and more damp.

Cavity Wall Insulation problems caused by condensation are often found near the floor on the ground level, and near the ceiling especially in the upper levels and bedrooms. Other danger areas for condensation are near windows and doors.

Installers should carry out fill checks on site prior to installing insulation and this is typically done in a see-through test box and done to check the machines and insulation material all perform and fill as they should. Most installers did not carry this out. We have seen very little evidence of this from hundreds of installers on thousands of houses installed with cavity Wall Insulation.

Another method where insulation can get wet and cause damp is where rubble in the cavity is not removed and bridges over the damp proof course and then more than likely into the insulation and the damp comes from the bottom up and will cause damp around the bottom of your walls and skirting boards.

Properties near the coast often have a lot of sand that over the years has penetrated the cavities and builds up in the cavity and is already above the damp course line, meaning cavity wall insulation should never have been installed until the cavity was fully cleared of sand and rubble.

Damp cavity wall insulation of this nature can be some of the worst because when the rain hits the ground it gathers and around some elevations in particular and constantly soaks the insulation. Many parts of the UK encounter a lot of rain and this is a particularly big issue again with failed cavity wall insulation.

Damp can quickly cause mould and have an adverse and severe effects on the internal décor, furniture and fittings, and more importantly your health, so if you are worried that you may be experiencing the first signs of cavity wall insulation problems or want advice on making a claim against the installer or removing insulation, please don’t hesitate to get in touch with our friendly team.

Wall Cavity Claims are a regulated claims management company. We serve and help clients across England and Wales affected by failed wall cavity insulation.

Call us freephone 0800-8-654321

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Why might you need to have your cavity wall insulation removed?

When the right material is correctly installed, and your property is suitable and in good condition externally, cavity wall insulation will help your home stay warm, safe and energy efficient.

However, cavity wall insulation can cause penetrating damp, mould and excessive condensation if:

  • It’s old and worn
  • It was installed incorrectly
  • Your home is in a high exposure area. (Find out if yours is)
  • The cavity was not clear before the insulation was installed
  • The structure of your home is not suitable for cavity wall insulation
  • You have damaged walls such as cracks in the brickwork, render or pointing
  • Blockages have entered the cavity because of building works


  • Gaps in the insulation allow heat to escape and damp to penetrate
  • If the insulation gets wet it will act as a sponge, drawing water across and holding it against your walls
  • The insulation can prevent adequate ventilation and cause damage to, for example, a steel or timber frame, suspended wooden floors and can corrode wall ties.

It may take a few years before you notice anything, but damp could still be damaging your walls before it becomes obvious. It’s likely your energy costs will be rising too, as your heating will have to work harder to maintain a comfortable temperature.

If you think your cavity wall insulation may be damaging your home, we can help.

We can:

  1. Carry out a survey to see if your cavity wall insulation is damaging your home
  2. Advise you on how any problems we find can be resolved
  3. Remove problem cavity wall insulation
  4. Completely clear every elevation of any other materials or blockages.

Removing your cavity wall insulation

OSCAR is the accredited body that can certify quality workmanship has been maintained and that your cavity wall insulation extraction has been completed to a high standard and it is certificated to prove so.

  1. OSCAR approved extractors undertake a thorough process from start to finish and evidence the extraction. They can then let you know how much it will cost to clear your cavities.
  2. They prepare the site and erect scaffolding if necessary.
  3. They typically create openings at damp proof level in the external wall by removing bricks at predetermined distances right around the house.
  4. They fix specially designed extraction covers to the openings and attach an extractor.
  5. They drill a series of holes in the mortar line or render and use air pressure to force the insulation materials down to the extractor.
  6. They inspect the cavity at regular intervals throughout the extraction using a 360ovideo borescope that gives them a 2m view in every direction.
  7. When the extraction is complete, and they’ve confirmed all the cavities are completely clear they reinstate the walls and return your home to its original state.
  8. They then clear and clean the site.
  9. They carry out a final inspection of your property.
  10. OSCAR technicians should visit and carry out the final inspection to check the work has been done 100% correctly.

If you have a dispute about a previous installation of cavity wall insulation that you think may be causing damp in your home

Contact Wall Cavity Claims on Freephone 0800-8-654321