Frequently Asked Questions

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What are Cavity Walls?

Cavity walls were introduced on the exposed western coasts of Britain and Ireland in the nineteenth century, to stop wind driven rain from penetrating to the inside surfaces. They gradually spread to other, dryer, parts of the country, because the air layer trapped in the cavity was found to provide a degree of thermal insulation. Since 1945 this insulation quality has been enhanced by using lightweight blocks, rather than bricks, to build the inner leaf of the wall. But the main reason for building cavity walls has always been to keep the rain out.

In the 1980s, Building Regulations introduced requirements for new houses to be built with insulation material in the cavity. Since this time the government has been keen for home-owners to insulate their homes, even though cavity walls were built as a barrier against penetrating dampness and not intended to be completely filled.

As long as they were built correctly, this insulation should not compromise the walls’ resistance to rain penetration.

In most cases, the insulation is fixed to the inner leaf, leaving a narrow cavity to intercept any rainwater that penetrates the outer brick leaf. This insulation material is usually in the form of rigid foam boards, which are intrinsically waterproof, or semi-rigid mineral-wool or glass fibre “batts”, where the fibres are aligned vertically so that any penetrating rainwater should drain downwards in the cavity and not have the chance to penetrate across to the inner leaf.

Is Cavity Wall Insulation a Good Thing?

Cavity wall insulation when installed correctly is a fantastic way to help lower your energy bills. The insulation will slow the movement of heat across the wall and therefore your home will stay warm longer once you put your heating on, meaning you need to use less gas (if gas central heating) to give the home at a comfortable temperature. It is for this reason the Government are so keen to get homes to get it installed – after loft insulation, cavity wall insulation is the second most cost effective energy saving solution.

Why is Cavity Wall Insulation Failing?

Before 1995 there was no governing body to regulate the Cavity Wall Insulation (CWI) Industry. This lead to a large number of buildings receiving CWI even though they were unsuitable for this retrofit measure.

In other cases the CWI was incorrectly or poorly installed. For example, an incorrect drilling pattern or inconsistent filling and using incorrect material for the geographic location has resulted in a huge number of buildings developing damp and condensation issues. This has now been reported and linked to health issues on a wide scale resulting in class action against landlords, local authorities and Insulation contractors.

It’s said that incorrectly and poorly installed cavity wall insulation may affect as many as three million homes and rival PPI claims for compensation as a result of related health problems.

Why Remove Cavity Wall Insulation?

In the 1980’s building regulations stipulated that new buildings should be built with insulation installed during the construction phase. As soon as these regulations came into play, it became clear there were a huge number of slightly older properties that could also benefit from this type of insulation, however the only way to get the insulation into the cavity once the property was built was to inject it. Since the materials were cheap and the actual install process was relatively simple, the Government really pushed this and as such thousands of small installer companies popped up, knowing they could install the insulation in peoples home and be well paid for the work.

As a result, any property with an unfilled cavity was targeted regardless whether it was suitable or not – so obviously issues occurred – some of these issues are laid out below.

  1. The insulation material used was unsuitable – e.g. when urea-formaldehyde was used. The problems with this insulating product were two fold – firstly, it breaks down releasing formaldehyde into the home which is carcinogenic. Secondly, when the insulation breaks down it falls down the cavity, meaning walls higher up no longer benefit from the insulation.
  1. When cavity walls were first introduced in the 1930’s the cavity’s sole purpose was to prevent water crossing the wall and causing damp in the home. As a result the early cavities were very thin – so if these are retrofitted with cavity wall insulation, the insulation can cause bridges between the two skins of brick allowing water to cross the total width of the wall leading to damp issues in the home.
  1. Incorrectly installed – when the cavity wall installer puts the cavity wall insulation in the gap between the two skins of brick, the wall needs to be drilled in various places to allow an even distribution of the insulation. If the distances between the drilled holes were incorrect then the insulation would not meet leading to cold spots.
  1. Another issue when installing insulation was cut corners. Since the installer gets paid per m2 of wall, they need to do the jobs as quick as possible. When beads are injected into the cavity wall they are injected with a uPVC glue which binds all the beads together. The problem is that to do this properly (inject the glue with the beads) takes about 3 times longer than installing the beads alone, so some installers wouldn’t bother – instead they were looking to maximise profits. In this case, the beads tend to ‘settle’ in the bottom of the cavity, meaning no real insulating impact on the upper parts of the wall.
  1. Cavity wall insulation simply isn’t suitable! If a wall is privy to driving rain for instance, the cavity is required to prevent ingress of water into the home. If these walls are retrofitted with cavity wall insulation, it can very quickly lead to damp issues – this tends to occur in coastal regions for example.
  1. Another example of a wall being unsuitable is when we hear of timber frame properties getting cavity wall insulation installed. These properties should never have cavity wall insulation installed, however again a new, untrained installer will not spot this and install anyway to make sure they get paid for the job. We get several phone calls a month from homes who are in this situation and are trying to sell their properties, but are finding it impossible since mortgage companies won’t allow prospective buyers to get a mortgage on the property until the cavity wall insulation is removed.

The final reason, and we have encountered this a few times is when someone has just bought a property previously installed with cavity wall insulation. In some cases the insulation causes allergies for the new homeowner and again this needs to be removed despite the energy savings resulting from the installed cavity wall insulation.

What are the steps involved in CWI extraction?
  1. On-site Planning and Management including Risk Assessment
  2. Internal Pre-Extraction Checks. External Pre-Extraction Checks
  3. Pre-Extraction Instructions for Crew Assistant/s
  4. Identifying Extraction & Air Pressure Holes-Drilling
  5. Holes Drilling Pattern
  6. Identifying Extraction Drill Holes
  7. Identifying Air Pressure Drill Holes
  8. Air Pressure Holes Drilling Pattern
  9. Extraction Equipment Preparation
  10. Extraction Process
  11. Making Good
  12. Post-Extraction External Checks

Post-Extraction Internal Checks

How do you Remove CWI?

Removing cavity wall insulation depends on the material within the walls. If it is wool insulation we can simply extract it with what essentially is a giant vacuum cleaner (although made specifically for this task!). If it is solid insulation, it is more fiddly because we need to break up the insulation so it crumbles and can be removed safely. This is carried out using high pressure air blown within the cavity through injection holes via a compressor.

What Percentage Of Properties With CWI Experience Dampness Problems?

There are no hard statistics about growing epidemic, as no in depth research has not been completed. The manufacturers, installers, CIGA and HM Govt (through their quango the Energy Saving Trust) all refuse to acknowledge that cavity wall insulation can cause dampness problems.

MP Amber Rudd, did write a letter to reporter Jeff Howell of the Telegraph after his articles on this issue where she wrote berating him for “failing to recognise that the vast majority of (CWI) installations, over 99 per cent, go ahead without any problems”.

CIGA (Cavity Insulation Guarantee Agency) have stated “Problems with cavity wall insulation are exceedingly rare, affecting only around two in every 1,000 installations.” This would equate to some 12,000 of the six million homes covered by CIGA guarantees.

Amber Rudd’s figures of “over 99 per cent” success, would imply a failure rate of less than one per cent – let’s say 0.9 per cent, or 54,000 homes, I’m not quite sure why the Department of Energy and Climate Change’s (DECC) figure for failures should be four-and-a-half times greater than CIGA’s, but it is at least an admission that nobody knows the true figure. Both CIGA and DECC seem to be making the schoolboy error of mistaking absence of proof for proof of absence.

Infra-red imaging company IRT Surveys Ltd has surveyed 250,000 properties across the UK and found that one-third of homes are well insulated, one-third have no insulation at all, and one-third have damp, slumping or missing insulation. The third with no insulation at all will include all the solid-walled Georgian, Victorian and Edwardian houses. The other two-thirds will be predominantly cavity-walled properties, and these statistics indicate that HALF of these are likely to have faulty insulation. CIGA itself has issued six million guarantees, so if IRT’s findings hold true, this would indicate that some three million UK homes have current or potential CWI problems.

Does the removal process damage the walls?

No – in fact, when we clean the cavity we also remove pre-existing rocks and mortar that the builders had dropped down the cavity when it was being built – so the cavity is in better shape than before it was ever insulated.

Can cavity wall insulation be removed from any property?

We have helped many homeowners remove the cavity wall insulation from their homes having previously had it incorrectly installed. We are yet to encounter a property where we have been unable to remove the existing cavity wall insulation.

How long will it take to remove the insulation?

This is a little bit like asking how long is a piece of string – it depends entirely on the building in question. First we carry out a technical survey which will include prices, the plan of attack and a rough timeline.

Who regulates the Cavity Wall Insulation industry?

CIGA (the Cavity Insulation Guarantee Agency) has refused to acknowledge that the cavity wall insulation was the cause of quite literally thousands of people having to have failed CWI removed following the installation of blown mineral-wool fibre and incorrectly installed product from their walls which have become damp and moldy, and their homes have become uninhabitable and unsalable.

In nearly all cases the installers and CIGA have insisted that the dampness problems were due to construction faults in the building (even though these are supposed to be identified by the “surveyor” prior to installation) or to “lifestyle condensation” caused by the occupants (even though condensation had not been a problem prior to the CWI).

However there have been some recent cases where homeowners have taken their cases to litigation and won the argument. The growing issue has also been discussed in parliament.

What are the Efects Of Increased Rainfall On Cavity Walls?

A further point to the failure of CWI is due to buildings not being correctly maintained and modern day weather causing ongoing degradation to buildings, leading to the breakdown and failure of the CWI.

The issues buildings are now facing stem from the practices detailed above, along with dated insulation techniques that has lead to water penetration causing the insulation to become saturated. This breaks down the fabric and purpose of the insulation leading to the thermal properties and function becoming defective.

Property’s suffering from problems of damp, condensation and water ingress can be remedied by completely removing the old defective insulation material and obstructions of rubble and debris and installing the correct insulation product for the property, such as External / Internal Wall Insulation.

What are the Effects of Climate Change on Cavity Walls?

Since the early 1990’s it has been predicted that we will experience periods of considerably more adverse weather and increased periods of heavy rainfall than we had been used to. This has now become a much talked about point in recent years and well reported that weather conditions are becoming increasingly worse from one year to the next.

Properties within the blue areas should never have had the cavity walls filled using wool products. This is now causing a big problem for local authorities, housing associations and private home owners.

Rainfall clearly shown in reports for the UK, now shows more of the country to be in high exposure zones, where the amount of rain is far greater than previously reported or expected.

Buildings in these areas are now facing the growing issues of more driving rain that we have ever experienced before. This has lead to failure of insulation materials used, due to the wrong product being installed, the incorrect installation or simply the product was used when it should not have been.

How Much Does it Cost?

Unfortunately this is a difficult question to answer without first viewing your property.  This is entirely dependent on the type of property and the type of material in the walls.  Typically, to remove blown fibre or bead insulation the cost is £12-£16 per m2.  However, if there is rubble or debris in the cavity this can increase the cost.