How Do I Know If I Have Cavity Wall Insulation?

How do I know if I have cavity wall insulation?

Cavity walls exist in properties that do not have solid walls, and usually date after the 1920s. Without adequate insulation in these cavities, a home can be highly inefficient and add to your heating costs.

But what if you don’t know if your property has cavity walls, or indeed if they have already been insulated? There are ways to carry out a cavity wall check, and if you need to, to arrange to have cavity wall insulation fitted at your property. Read on to find out more…

What are Cavity Walls?

Cavity Walls are made up of two distinct walls that are regarded as one yet have a gap or cavity between them. A hollow wall’s two walls are known as its leaves, with the outer wall known as the external leaf and the interior wall known as the internal leaf.

A property that is without cavity walls will be of solid wall construction, and therefore there is no cavity to fill, in which case solid wall insulation is the suitable option.

What is Cavity Wall Insulation?

Cavity wall insulation is an insulating material, such as mineral wool, polystyrene beads, polyurethane foam, that can be installed in the space or cavity between the inner and outer walls of a home. When installed correctly, it is a cost effective technique for retaining heat in a home. As heat rises, it tries to escape the warm boundaries of an indoor environment and will quickly attempt to move outdoors into the colder air.

Cavity wall insulation can include spraying expanding foam into a cavity wall to create an additional barrier between your home and the colder conditions outside. Installing wall insulation minimises heat loss inside a home — up to 35% of all the heat lost in a home is thought to be through uninsulated walls.

What exactly is cavity wall insulation?
Image: What is cavity wall insulation?

How Do I Know If My Property Has Cavity Wall Insulation?

There are several ways to identify whether your home has cavity walls and if you already have cavity wall insulation installed.

Look at your property’s EPC (Energy Performance Certificate)

The EPC, which is a measure of how energy efficient a property is, should specify the type of walls of your home. It will usually state if they are cavity or solid in structure.

If you can’t find your EPC at home, you can use your postcode to look it up on the Government’s EPC Register. Visit and click the “Retrieve Report Using Property Address” button.To download your EPC, enter your postcode and choose your home address. The second page will show the wall type and insulation.

Check when your property was built

Your home is likely to have cavity walls if it was built after the 1920s. Solid walls are more commonly found with older properties. Houses built after the 1990s most likely had cavity wall insulation installed at the time as was required by building regulations.

Check the brickwork pattern on outside walls

Check the brickwork on the external wall of your house to see if you have a cavity wall or not. If your house has cavity walls, the bricks will typically be laid in a regular manner, with the bricks arranged lengthwise on the outside wall.

Cavity wall
Image: A cavity wall

Solid, single walls are typically less consistent and have a more uneven brick pattern, displaying both the square ends of bricks and bricks stacked lengthwise.

Uneven Wall Pattern
Image: Solid brick wall

If your brickwork has been covered by render you can usually identify the status of the brick wall by measuring the width of the wall. Examine a window or door on one of your external walls to accomplish this. If a brick wall is more than 300mm thick (from the exterior to an inner wall), it most likely has a cavity; a narrower wall is most likely a solid wall. Stone walls can be even thicker, but they are usually sturdy.

Look for other signs on external walls

Many contractors should have installed unique air vents which can be a good indication that cavity wall insulation has been installed to a high grade of quality.

Small holes or bore holes in the masonry walls are another sign that you probably already have cavity wall insulation fitted. As part of an energy or insulation survey, many companies will conduct this test to determine whether insulation material actually has been installed.

Get Cavity Wall Insulation Installed

If you discover that you have unfilled cavity walls, or they are inadequately insulated, and your home is usually cold regardless of how much you crank up the heating, it is critical that you look at installing cavity wall insulation.

If your home is persistently cold, this likely indicates that heat is escaping from your property, implying that your home is insufficiently insulated. You could be wasting money every time you switch on the heating and also adding to your carbon footprint.

Cavity wall insulation is not for the typical DIYer, and it is always recommended that you speak with an registered installer who will run over your wall insulation options and the costs involved. They should also be able to tell you how much you could improve your home energy efficiency and lower energy bills if you get sufficient cavity wall insulation installed in your home.

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