Should I remove my cavity wall insulation?
Not always. Welsh Government guidance makes the point that extraction is not always the right remedy. Damp can come from blocked gutters, failed pointing, bridged damp-proof courses or condensation, none of which removal fixes. We start with a damp investigation and borescope checks, then recommend removal only where the fill itself is the problem.
How extraction works
Bricks are carefully removed in a line near the base and at intervals higher up where needed. The fill is broken up and drawn out with an extraction vacuum, the cavity is cleared and checked with a camera, and the bricks are rebuilt in matching mortar. Extracted material is bagged and disposed of properly.
If you have a guarantee
Contact your original installer first. If that does not resolve it within two months, CIGA's process applies for CIGA-guaranteed installs. Removing insulation yourself can void a guarantee, so speak to the provider before work.
What is included
- Damp investigation and borescope diagnosis first
- Brick removal and reinstatement
- Full extraction and cavity clean
- Camera check before rebuild
- Waste disposal
- Option to refill with a suitable system
Cavity wall insulation removal prices
| Cavity wall insulation removal guide prices | Guide price |
|---|---|
| Detached house | £2,595–£4,195 |
| Semi-detached house | £1,695–£2,795 |
| End-terrace house | £1,395–£2,395 |
| Detached bungalow | £1,395–£2,395 |
| Semi-detached bungalow | £1,195–£1,695 |
| Mid-terrace house | £1,195–£1,595 |
This work is not insulation, so it is normally standard-rated for VAT. Guide prices include VAT where it applies. Guide ranges only: the fixed price is confirmed in writing before any work starts, and anything that could not be seen at survey is agreed with you first.
Rules and funding by nation
The building regulations route and the funding schemes differ between England, Wales, Scotland and Northern Ireland. The local pages for your area explain the rules where you are; in short:
- England: Filling a cavity is notifiable building work and needs a building notice or competent-person self-certification.
- Wales: Filling a cavity is notifiable work under the Building Regulations as they apply in Wales, usually self-certified through a competent person scheme.
- Scotland: No building warrant is needed for insulation within a wall, but the work must meet the building standards.
- Northern Ireland: Inserting cavity wall insulation needs a building control application to the council before work starts.
Sources: Energy Saving Trust: cavity wall insulation; Planning Portal: cavity wall insulation and building regulations; Welsh Government: building work competent person schemes; Welsh Government: issues arising from cavity wall insulation installations; CIGA: the CIGA guarantee; HMRC: VAT on energy-saving materials (Notice 708/6).