Is Cavity Wall Insulation a Good Idea For Your Home?
Understand the pros and cons of cavity wall insulation.
Published: September 28, 2022 Author: Matt Jackson
Cavity wall insulation has grown in popularity in the UK over recent years.
You may have seen several neighbours having it pumped into their houses.
But is it a good thing?
Well, while cavity wall insulation is helpful, there are some areas of the house that it is a bad idea to insulate. Retrofit cavity wall insulation is one of these problem areas.
So, what actually is cavity wall insulation?
Retrofit cavity wall insulation is basically an insulating material that is injected into the gap between the outer and inner brickwork layers of your external wall.
Filling the gap with insulating material is meant to reduce the amount of energy that you lose through your walls.
How is cavity wall insulation installed?
A company will drill small holes into the outer layer of your brickwork and pump millions of little polystyrene balls (they’re actually called EPS balls) into the gap between the two brickwork layers.
Then they fill the holes in your wall, and the process is complete.
1. Risk of Damp
The gap is there for a reason to begin with. By filling the gap between the two layers of brickwork you will inevitably create a bridge between the outer and inner layers. Which means a barrier will be created between hot (inside your home) and cold (the outside temperature) and between the wet outside and dry inside of your home.
If water enters the gap, it will run down the outer layer of your brickwork and dry out (For that reason airbricks are important). If you have retrofit cavity wall insulation in your property then the water should run down through the non-absorbent insulation balls and come out at the bottom
However, if you live in a wet area like myself, you will face the same problem that I face. Due to the weather always being wet and windy. The cavity will not have sufficient time to dry, consequently the moisture could transfer to your inner wall and thus entering your home.
2. Lack of Accurate Coverage
Moreover, the people installing the insulation are essentially blind to how they are filling the gaps, since they can’t see it. Although they drill a lot of holes to make sure it is sufficiently filled, some areas in the wall might be left without insulation.
This not only keep in the heat; it also creates a thermal bridge which is basically a vulnerable spot in the insulation that permits cold and hot air to mix. The difference in temperature caused by this will result in condensation that can result in damp issues.
In conclusion, this is something that I prefer not to go through and if you are on the same boat as I am and you have a cavity that is less than 5cm wide. Don’t do it. You are free to do whatever you like, but it’s just my advice.
Hopefully new technology might arise in the future that fixes this but at the moment it’s not worth the risk.
Dare I say that I would not even consider buying a house that has retrofit cavity wall insulation. I know that this sounds a bit extreme, especially when you consider the state our home was in when we bought it, but for me, it just comes with too many risks and it is not worth it.
What if I’ve already had retrofit cavity wall insulation installed?
If you already live in a house that has retrofit cavity wall insulation, a good idea is to have your house scanned with an infrared camera.
This will allow you to check whether the insulation is evenly distributed or not. In addition, it will also allow you to check for gaps that need filling so not to cause thermal bridging problems in the future.
A further precaution that I would recommend is checking your pointing and gullys just to make sure that everything is well maintained and to avoid any unnecessary issues that may arise in the future.
Conclusion
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