Cavity insulation for new builds and extensions for Harrow properties
If your property is in Harrow or the HA1 district or nearby Wembley, Northolt and Greenford, it is within our Greater London coverage. It is roughly 10 miles north-west of London.
Where a Harrow property has an extension or a conservatory, we check how the old and new walls meet, because that junction is often missed. A suitable wall in Harrow is usually filled in a single day from outside, with drill holes made good to match the pointing.
Wind-driven rain is the first thing the surveyor weighs up. 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.
For regulations, in Harrow 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.
What we work from
Your architect's or designer's specification and the energy calculation for the job. We match the product, thickness and fixing to that spec, keep cavities clean as the walls rise, and fit cavity trays, closers and stop ends where shown so the building control inspection goes smoothly.
What is included in Harrow
- Coordination with your bricklayers
- Batts or boards to the specified U-value
- Photo record for building control
- Trays, closers and stop ends as drawn
Guide prices for Harrow
| 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 Harrow:
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.