Fill in the gap with cavity wall insulation

The majority of homes built between the 1920s and 1990s have a gap - or cavity - in the walls. Designed to stop rainwater coming into your property, this cavity unfortunately allows precious heat to escape. Taking steps to fill the gap will make your home more efficient and save you money on your energy bills.

What kind of walls do you have?

Buildings designed before the 1920s usually have solid brick walls, while those built after the 1990s have added insulation to minimise heat loss. Otherwise, most homes in the UK will likely have a gap between two layers of wall. 

If you’re unsure, taking a look at the wall itself will give you some clues as to whether or not you have cavity walls, as all the bricks will be laid lengthwise. Solid walls, on the other hand, can be easily recognised by their alternating pattern, with bricks laid both lengthwise and crosswise.

If you can’t see the brickwork because it’s covered with paint or wallpaper, the width of the wall will also help you figure out whether it’s solid or not. You can measure the wall at a window or door - if it’s over 260mm thick, there’s probably a gap, while thinner walls are likely to be solid. 

There are special cases where you should consult a professional to decipher what kind of wall you have, such as if your home is a steel-frame or timber-framed building, or made from prefab concrete.

How much can you save from insulating your cavity walls?

The savings you’ll see on your energy bills from undertaking this type of insulation will depend on the size of your house. According to the Energy Saving Trust, the installation cost can go up to £1,000 for a mid-floor flat, £2,700 for a semi-detached house, and £4,600 for a detached house, while yearly savings can reach up to £135, £165, and £185 respectively. 

Who shouldn’t install cavity wall insulation? 

Some people have experienced damp and mould after their cavity wall insulation wasn’t installed properly - or perhaps shouldn’t have been installed at all. Homes that are often exposed to wind-driven rain - many of which are situated on the west coast of the UK - are most at risk of these issues. Check with your installer, and get a second opinion if you’re still unsure your home is suitable.

How can you insulate cavity walls? 

Cavity wall insulation isn’t a task you should take on yourself - it should be done by a professional. They’ll inject insulation into a hole in the wall from the outside, then seal the holes with cement so they won’t be noticeable. The insulation material will typically be either mineral wool, polystyrene beads, or polyurethane foam.

Want a warmer and more comfortable home with cheaper energy bills? Start with your Heatio Home Energy Score today.

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