Cavity insulation for new builds and extensions for Letchworth Garden City properties
If your property is in Letchworth Garden City or the SG6 district or nearby Hitchin, Stevenage and Welwyn Garden City, it is within our Hertfordshire coverage. It is around 17 miles north of St Albans.
Where a Letchworth Garden City property has an extension or a conservatory, we check how the old and new walls meet, because that junction is often missed. For semi-detached and terraced homes in Letchworth Garden City, cavity barriers are fitted where your wall meets your neighbour's so the fill stays on your side.
Local weather affects which walls can be filled. Much of Hertfordshire 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.
As for paperwork, in Letchworth Garden City 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 Letchworth Garden City
- Coordination with your bricklayers
- Trays, closers and stop ends as drawn
- Clean-cavity working
- Photo record for building control
Guide prices for Letchworth Garden City
| 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.
How it works in Letchworth Garden City:
Tell us about the property
Postcode, property type and what you need.
Free survey
Walls, cavity, condition and exposure checked and photographed.
Written result and price
Suitable, suitable after repairs, or not suitable, with a fixed price.
Work and paperwork
Installation, making good, and the regulations and guarantee paperwork.