Cavity wall insulation

Claim 66% off with the Green Homes Grant and save up to £280 a year on energy bills(1) with cavity wall insulation that stops 33% of heat from escaping.

from £600 £204

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Middle aged couple happy outside their home

Waste 33% less heat and save £280 a year on energy bills(1)

Cavity wall insulation is one of the best and most affordable things you can do to improve your home's energy efficiency.

For a typical home, cavity wall insulation starts from £204 with the Green Homes Grant.

The Green Homes Grant means you could get two-thirds off the cost, so there's never been a better time to consider it.

Cavity wall insulation - Installing cavity wall insulation

What is cavity wall insulation?

Houses in the UK mostly have either cavity walls or solid walls:

  • Cavity walls are made of two layers with a gap or ‘cavity’ between them. If your home was built after the 1920s, it's likely to have cavity wall.
  • Solid walls have no gap, so they can’t be filled with cavity wall insulation. If your home was built before the 1920s, it's likely the external walls are solid walls rather than cavity walls


Cavity walls can be insulated by injecting insulation into the cavity from the outside through drill holes in the outside walls.

Insulation is usually mineral wool or polystyrene beads or polyurethane foam.

Cavity wall brick pattern example 1
Cavity wall brick pattern example 2
Cavity wall brick pattern example 4
Cavity wall brick pattern example 3

How can I tell if I have a cavity wall?

There are some common ways to tell if your property has a cavity wall:

  • It was built after 1920; homes built within the last 40 years almost certainly do
  • It has walls more than 260mm thick
  • It has brickwork like below

Why is cavity wall insulation a good idea?

Insulating the cavity space between the outside and inside wall adds a barrier to stop the cold from coming in and heat from escaping.

Save up to £280 on energy bills

Less heat escaping means less energy used to heat your home, saving you money.

Reduce your carbon footprint

Wasting less energy to heat your home, means your carbon emissions will drop

Better EPC rating

Your home will be more energy-efficient and more attractive to buyers

Get 66% off now

Claim Green Homes Grant vouchers to cover 66% of the cost

What our customers say

I have noticed a huge difference in the warmth of my home. Before I was having the heating on not just high during the day but also I had to keep it on through the evening during very cold winter nights. This was extremely expensive.

Mr H, Kingston

How can I fund my cavity wall insulation?

There's other insulation to consider

thermal loft insulation roll

Loft insulation

from £136

Around 25% of your heating can be lost into through your roof - save up to £250 a year on energy bills(2)

installing external wall insulation

Solid wall insulation

from £2,516

Save as much as £375 a year on heating bills(3) and transform the look of your home.

Insulation and energy-saving advice