Cavity insulation for new builds and extensions for Swanley properties
We cover Swanley and the BR8 postcode district, including nearby Dartford, Sevenoaks and Gravesend. It is about 17 miles north-west of Maidstone.
Swanley properties with rendered or painted walls get a closer look at the outer finish, because cracked render can let rain behind it. Where a Swanley property has an extension or a conservatory, we check how the old and new walls meet, because that junction is often missed.
Exposure matters for every cavity wall. Much of Kent 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.
For regulations, in Swanley 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 Swanley
- Batts or boards to the specified U-value
- Coordination with your bricklayers
- Clean-cavity working
- Photo record for building control
Guide prices for Swanley
| 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.
What happens next for a Swanley property:
Send your details
A minute online, or call the free number.
We check the walls
Construction, cavity width, debris, damp and wind-driven rain exposure.
You decide
Plain-English result and a fixed price, with no pressure to book.
Job done properly
Holes made good, paperwork handed over, guarantee details confirmed.