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. In some cases though, cavity wall insulation simply isn’t the answer – the good news is that it can be rectified, the bad news is that there is a cost.
7 reasons why you would 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.
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.
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.
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.
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.
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.
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.