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Cavity Wall Extraction FAQs

We are regularly asked questions regarding cavity wall extration, please see below for cavity wall insulation extraction FAQs:

What is cavity wall insulation?

Cavity wall insulation is a layer of insulation that is installed in a cavity wall, that is between the outer and inner skins of brick or block.

Cavity Wall Insulation

These days cavity wall insulation is normally installed when the house is built however in times gone by cavities were left entirely clear when they were built. To keep these older properties warmer and reduce heating bills it was determined that retro fitted or ‘blown’ cavity wall insulation was a viable option. Generally speaking, there are three main categories of cavity wall insulation: fibre, bead and foam. All are installed in much the same way: by injection through a pattern of small holes through the outer (or inner) skin of the cavity wall.

Can I remove cavity wall insulation?

Yes, most types of cavity wall insulation can be removed by a specialist contractor. Blown fibre and bead cavity wall insulation is relatively straightforward to remove with the right equipment, however foam insulation can be much more stubborn. Wet cavity wall insulation or insulation mixed up with rubble can also be more difficult to remove, but with patience and the right tools and techniques cavity walls can be successfully cleared.

How can I tell if I have cavity wall insulation?

The only way to know for certain if you have cavity wall insulation is to inspect the inside of the cavity wall, either by removing a brick or by inserting a small inspection camera through a drill hole in the wall. Homeworks Energy can do this for you, but most builders or general handymen should be able to help. There are other clues to help you: for instance, you may be able to spot the original drill pattern used to inject the cavity wall insulation into the wall (look particularly for small drill holes under windows). You may also have a guarantee certificate, usually issued by the Cavity Insulation Guarantee Agency (CIGA) which will confirm that your property has been treated with cavity wall insulation. If need more help determining if you have cavity wall insulaiton, please contact us.

What are the signs of problems with cavity wall insulation?

The vast majority of cavity wall insulation installations create no problems. It has helped many thousands of people reduce their fuel bills and keep their homes warmer. However, if cavity wall insulation was not installed correctly or to the appropriate type of house, problems can occur.

The most common sign of problems is cavity wall insulation damp. This can present in a number of ways, but the most common forms are penetrative (water ingress from the outside in) and condensing (water vapour condensing on cold spots internally). Penetrative damp can occur in areas of high exposure: when the cavity wall is particular susceptible to wind driven rain. If the cavity wall insulation has not been fitted properly (to the right density) it can become wet and this may eventually present internally. By contrast, condensation can sometimes occur when cavity wall insulation has not been fitted fully to the entirety of the cavity wall and cold spots remain. These areas attract warm air which then condenses on the colder surface and can encourage mould growth.

Why should you remove cavity wall insulation?

The great majority of cavity wall insulation is doing a good job and should be left well alone to help keep heat in homes.

Reason why you should remove cavity wall insulation:

  • The property has been subject to fire or flood
  • The cavity wall has been infested by pests
  • The property suffers from damp that can be attributed to wet cavity wall insulation
  • Cavity wall insulation has been improperly installed
  • The cavity wall insulation is old and beyond its useful economic life (generally considered to be 30 years or so) and therefore needs to be replaced
  • The cavity wall insulation has in some way been compromised (perhaps spilled out during the construction of an extension) and needs to be removed and replaced

See also: Cavity wall insulation problems

How is cavity wall insulation removed?

It is really only possible to remove cavity wall insulation by using a specialist contractor; such as Homeworks Energy. The procedure involves three main techniques:

  1. The use of a specialist industrial vacuum fitted to extraction points at the foot of the cavity wall
  2. The introduction of compressed air to blow the insulation down the wall
  3. The use of a ‘whip’ to agitate stubborn pockets of cavity wall insulation where they occur.

Through a combination of these techniques, we are able to gradually move the cavity wall insulation down the wall and into specially sealed bags for disposal. We use the XtractaVac system developed by Stewart Energy for this purpose.

How much does it cost to extract cavity wall insulation?

There are a number of factors that affect the price of cavity wall insulation removal (for instance: insulation type, location, house type and size and accessibility). As a guide it typically costs in the region of £1,200 – £1,800 to remove insulation from a three bed semi detached house. Small houses maybe a little cheaper and larger detached houses a little more expensive. The work to remove cavity wall insulation often takes 2-3 days, but again this depends on a number of factors. Please contact us for a free consultation and quotation.

Should I replace my cavity wall insulation?

If you are concerned that your cavity wall insulation is too old, has been damaged or has been installed incorrectly and this is leading to problems, then it may need replacing. Before new insulation is fitted, the property must be carefully surveyed to ensure that it is suitable for cavity wall insulation. Homeworks Energy can help you at every stage. Please contact us at the Homeworks Energy head office for further advice and assistance.