Key differences between cavity wall insulation and solid wall insulation

There are two main types of insulation for your walls; cavity wall insulation and solid wall insulation. While they both do the same job, there are a few crucial differences between the two products which determine how effectively they will do the work they need to do. Sometimes, this can get a bit confusing, especially when you’re not a trained insulation installer. Below, the key differences between cavity wall insulation and solid wall insulation have been outlined.

Cavity walls and cavity wall insulation

Cavity walls were developed in the first half of the 20th century, as a method of combating damp. Rather than having one solid wall, cavity walls are composed of two layers of brick with a gap in the middle. The gap can be anything from 20 to 100mm wide, meaning that cavity walls are generally much wider than solid brick walls.

Cavity wall insulation is installed in the wall “cavity” between the two layers of brick. Most newbuilds are built with insulation already installed, but when it is retrofitted into over properties, the options are fiberglass type insulation or polystyrene bead insulation.

Solid walls and solid wall insulation

A solid wall is exactly what it sounds like. Rows of bricks that interlock to form a completely solid 9 inch brick wall. There is no gap between the bricks to insulate, so homeowners must choose between internal and external wall insulation.

What’s the price difference?

The price difference between cavity wall and solid wall insulation comes as a shock to many. While cavity wall insulation sits at roughly £5 – 8 per square metre, solid wall insulation averages at £100 per square metre. The worst part is, homeowners don’t get a choice about which they get installed. If you don’t have cavity walls, you’ll be searching for “external wall insulation near me” and hoping you don’t get your eyes torn out!

How efficient are they?

If your home was built before 1985 and has cavity walls, the insulation will not be nearly as effective as solid wall insulation. This is because the cavity wall only has a gap of 40mm, and when comparing that to 100mm of solid wall insulation, there is no competition in terms of efficiency. Some people who have had cavity wall insulation installed have reported still feeling cold in their home, simply due to the layer of insulation being thin.

How long does it take?

A typical cavity wall insulation installation only takes a few hours for the entire home. A solid wall insulation installation however takes much longer, and depends on whether you opt for internal or external insulation. Choosing internal wall insulation could see you needing your entire house redecorating and furniture replacing, so most installers suggest having this done to one room at a time, as you plan to redecorate.

When it comes to cavity wall insulation and solid wall insulation there is no real “winner”. Both options stand to improve the energy efficiency of your home. The best choice is totally dependent on the construction of your house and how much you can afford to pay.