Reasons why your cavity wall insulation has failed
When cavity wall insulation has been installed properly, it can help you to reduce your heating bills and conserve energy. That is when it has been installed properly and has not be compromised. Before we discuss the various problems, your cavity wall insulation could be having that’s causing it to fail, it’s worth discussing the difference between solid walls and cavity walls and what cavity wall insulation involves.
What if you don’t know if you have cavity wall insulation or not? Generally, if your house was built after the 90’s, it will have wall insulation. However, if it is older, it is possible that it may not have any insulation whatsoever.
Whether you have cavity wall insulation or not also depends on the type of walls your property has. In the UK, houses tend to have either cavity walls or solid walls.
Houses built after the 20’s, usually have cavity walls, while those built before the 1920s tend to have solid walls.
What is a Cavity Wall?
Compared to a solid wall, which is just as it sounds – a single solid wall – a cavity wall consists of two walls that have a gap between them, which is what is referred to as a cavity. While the outer leaf, or wall is normally constructed from bricks, the internal leaf is made of concrete block or brick.
If you do not know what kind of walls you have in your property and have no access to information that could explain it, there is an easy way to check. If the exterior of your property has visible brickwork, look at the pattern. A building with cavity walls has bricks that have been assembled so that all the bricks have been laid lengthways. A solid wall, on the other hand, is one where the bricks have been laid with some across, so that the ends are what you see.
Now that you have a better idea how to identify a cavity wall, let’s look a little deeper to what cavity wall insulation involves.
How Does Cavity Wall Insulation Work?
Injecting special insulation material into the cavity between the two walls is the most common way to install cavity wall insulation. This is handled by a special firm that starts by drilling holes of around 22mm spaced 1m apart, from the outside and then injecting the special material before sealing over the holes with cement. Although the most common insulation materials used are polystyrene beads and mineral wool, there are occasions when polyurethane foam is used.
This then forms a seal that stops warm air escaping from the house into the cavity and prevents cold air making its way into the property.
That is the theory at least. In practice, the results vary considerably. As posed in the heading though we are going to look at some of the reasons why your cavity wall insulation is failing.
The most common problems that could be causing your cavity wall insulation to fail are:
- Penetrating Damp – By far the most common reason for failed cavity wall insulation is moisture penetrating through the cavity that can lead to damaged décor, joinery and damp stains in your property.
- Corrosion of Wall Ties – This is when corrosion affects the wall ties that holds the wall leaves together
- Badly Installed Insulation – If insulation hasn’t been fitted properly and there are cold spots where there is no insulation in the cavity.
- Spray Foam Insulation – A newer method of insulation that is often used in retrofit cavities. Although effective in the short term, over time this style has been known to breakdown and shrink.
Cavity Wall Insulation Damp
There are a lot of experts who recommend avoiding retrofit cavity wall insulation because of instances of this cavity wall insulation causing damp. However, that is not strictly true. Yes, filling cavities creates bridges for moisture to travel across. The mistake many make is condemning all insulation material used when not all actually cause problems.
Most commonly, cavity wall insulation types that have been blown mineral wool and expanded polystyrene beads.
Mineral wool is the exact same material you may be familiar with in loft insulation. Tis type of insulation acts like a big sponge inside the cavity. So, when water enters the cavity, it gets absorbed by the insulation, which retains the moisture.
Although that stops the water getting into your home, it also means that you have a cavity packed with wet mineral fibre that will get cold – much colder than the cavity would be if it was empty. The real cavity wall insulation damp issue comes if you live in an area where there is a lot of driven rain or your property has defects that allows a constant stream of penetrating damp to keep it topped up. This constant moisture is able then to penetrate the interior leaf causing damages and won’t dry out.
As a further complication because it is cold and connected to the interior leaf, there is an increased risk of condensation and black mould.
Expanded Polystyrene Beads
Now, consider ESP insulation, which consists of many small polystyrene balls and imagine what happens when water pours on the top of the cavity. Where is it going go? It will move around over the balls and make its way down, touching any ball as it drips down and reaches the bottom.
Obviously, there is the possibility that the water will get inside the cavity’s inner edge. However, this should dry out quite easily, as this material does not absorb moisture. The only way it could cause problems with it not drying out properly is if you have building defect or wind-driven rain producing too much moisture for it to deal with., leading to cavity wall insulation polystyrene beads problems.
While both can result in cavity wall insulation damp, you have a much better chance of the wall drying out before anything too serious happens with cavity wall insulation beads.
Whereas with blown fibre or mineral wool has been used and subsequently gotten wet, it is best to speak to an expert about cavity wall insulation removal cost and have your cavity wall insulation removed.
Corrosion of Wall Ties
The leaves of the cavity wall in your property are tied together using little metallic strips known as wall ties. As that description suggests, yes, they are crucial. Not only can they be rather expensive to replace, but you can’t tell if they have failed until horizontal cracks appear and they are beyond repair.
You may wonder how failed cavity wall insulation connects to failed wall ties. Well, unless your cavity is packed full of insulation and there is no way for moisture to get in, penetrating damp can cause rust to occur much quicker. When moisture gets trapped in the cavity insulation as illustrated above, that means the wall ties are in constant exposure to the water.
Badly Installed Insulation
Similarly, to how penetrating damp, badly installed insulation is more of a problem for homes with blown fibre rather than EPS. The reason for this is because of the physical properties of mineral fibre insulation. Think for a second just how rough the inside of cavity walls is with rough surfaces and edges of the metal wall ties, bricks and blocks. When the wall insulation is retrofitted, the blown material catches on all those sharp edges and this can create gaps in the insulation.
The only real way to repair this issue is by finding the gaps and filling these with more.
EPS though can still be badly fitted. When beads are used and not glued, if you ever carry work out on the cavity walls you could end up with a lot of it seeping out. While glued EPS beads are used, because the glue is added just before being pumped in, human errors can cause problems, with voids being created as they are fitted.
Now that you hopefully understand why you have failed cavity wall insulation, you may be wondering what can be done about it. Well, you need to contact a specialist like LMG Home Improvements to find out the cavity wall insulation removal cost and all related cavity wall insulation help.
What types of cavity wall insulation do we remove?
Our cavity wall insulation extraction service removes mineral fibre like Rockwool and whitewool. We can also remove urea formaldehyde and polybead type insulations.
How do we remove failed insulation?
Following an initial inspection, if defects are found, a team will arrive on site and following their risk assessments will proceed to drill out the property. It will be drilled in a specialist pattern using original holes where possible. It will be necessary to open up vents and remove bricks at designated spots just above damp course level to allow exit points for the insulation to be removed.
Through the holes that are drilled, the operatives will drive compressed air through a rubber agitating whip and directional nozzle to break up and move the material to the exit points opened up.
An industrial vacuum then collects the material from the exit points and the operatives will work in a set pattern to move through the cavity ensuring that the material is removed.
The bricks are then replaced or vents installed dependent on our customers requirements
What happens to the defective insulation material?
The material is pumped into net stocking which is tied up and removed from site via our waste carrier licence and a clean down of the pathways around the property is completed to ensure any debris is cleaned up.
We can also provide photographic evidence if requested in advance of the inside of the cavity once the insulation is removed.