Why refill at all?
Often the original problem was the wrong material for the exposure, poor installation or defects in the outer wall, not cavity insulation as such. Once the defects are fixed and the cavity is clean, a suitable certified system can usually go back in. Where the wall is too exposed for any fill, we say so and leave it empty.
What is included
- Diagnosis and extraction
- Repairs to pointing, gutters or render where needed
- Clean-cavity camera check
- Refill with a suitable certified system
- Regulations route and guarantee named on the quote
Remove and refill prices
| Remove and refill guide prices | Guide price |
|---|---|
| Detached house | £3,895–£6,495 |
| Semi-detached house | £2,495–£4,295 |
| End-terrace house | £2,095–£3,795 |
| Detached bungalow | £2,095–£3,795 |
| Semi-detached bungalow | £1,695–£2,695 |
| Mid-terrace house | £1,595–£2,495 |
Removal is normally standard-rated and installing insulation in a home is zero-rated until 31 March 2027; 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).