Cavity insulation for new builds and extensions for Barnes properties
If your property is in Barnes or the SW13 district or nearby Chiswick, Putney and Fulham, it is within our Greater London coverage. It is around 6 miles south-west of London.
A suitable wall in Barnes is usually filled in a single day from outside, with drill holes made good to match the pointing. Barnes properties with rendered or painted walls get a closer look at the outer finish, because cracked render can let rain behind it.
Local weather affects which walls can be filled. Much of Greater London sits in the more sheltered driving-rain zones of the UK, which widens the choice of fill. Exposed elevations, coastal sites and high ground still get checked wall by wall.
On the rules side, in Barnes filling a cavity is notifiable building work and needs a building notice or competent-person self-certification.
Funding in England
In England, ECO4 runs to 31 December 2026 and Warm Homes: Local Grant supports low-income households through councils.
Sources: GOV.UK: extending the ECO4 end date, government response; GOV.UK: Warm Homes Plan.
Extensions that join an older house
Where an extension meets an existing cavity wall, the junction is a weak point. We can borescope and fill the existing wall at the same time so the old and new walls perform together.
What is included in Barnes
- Batts or boards to the specified U-value
- Coordination with your bricklayers
- Clean-cavity working
- Photo record for building control
Guide prices for Barnes
| Cavity insulation for new builds and extensions guide prices | Guide price |
|---|---|
| Full-fill batts supplied and fitted, per m² | £9–£16 |
| Partial-fill boards supplied and fitted, per m² | £14–£26 |
Prices are shown before any VAT; the VAT treatment for new-build work is confirmed on your quote. 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.
The steps for cavity insulation for new builds and extensions in Barnes:
Get in touch
Online, by phone or WhatsApp, whichever suits you.
Survey visit
The surveyor checks each wall and looks into the cavity where needed.
Your result in writing
What we found, what it means, and a fixed price if work is needed.
Booked work
Carried out by the installer named on your quote, with their scheme registrations.