Yes — If You Qualify
Cavity wall insulation is completely free through two government schemes: ECO4 (if you receive qualifying benefits) and GBIS (if your home is in council tax bands A-D). Around 8 million UK homes have unfilled cavity walls, and most of them qualify for free insulation.
How to Tell If You Have Cavity Walls
Most homes built between 1920 and 1990 have cavity walls — two layers of brick with a gap between them. You can usually tell by looking at the brickwork:
- Cavity walls: All bricks are the same length (stretcher bond)
- Solid walls: Mix of long and short bricks (header bond)
Your EPC will also state whether your walls are insulated or not.
How Much Does It Save?
Cavity wall insulation saves £195-£595 per year depending on your property type:
- Detached house: up to £595/year
- Semi-detached: up to £395/year
- Mid-terrace: up to £195/year
- Bungalow: up to £295/year
How Is It Installed?
Cavity wall insulation is one of the least disruptive home improvements:
- Small holes (about 22mm) are drilled into the external mortar joints
- Insulation material is injected through the holes
- Holes are sealed and colour-matched
- The whole process takes 2-3 hours
There's no internal disruption — you don't need to move furniture or redecorate.
Who Pays for It?
Through ECO4 and GBIS, your energy supplier pays the full cost. Cavity wall insulation normally costs £1,500-£3,000 if you paid privately. Through the grant schemes, it's completely free.
Check If Your Home Qualifies
Use our eligibility checker — enter your postcode and we'll tell you in 60 seconds whether you can get free cavity wall insulation.