Cavity insulation for new builds and extensions for Swansea properties
We cover Swansea and the SA1 postcode district, including nearby Briton Ferry, Gorseinon and Neath. Swansea is one of the main towns we cover in West Glamorgan.
If a wall in Swansea is not suitable, for example because of an undiagnosed damp patch or a very exposed gable, you are told so in writing with the reason. For semi-detached and terraced homes in Swansea, cavity barriers are fitted where your wall meets your neighbour's so the fill stays on your side.
Every elevation is judged on its own exposure. Parts of West Glamorgan face some of the heaviest wind-driven rain in the UK, especially exposed coastal and upland sites. Here the survey is stricter: some walls suit only certain certified systems, and some should not be filled at all.
In terms of approvals, in Swansea filling a cavity is notifiable work under the Building Regulations as they apply in Wales, usually self-certified through a competent person scheme.
Funding in Wales
In Wales, Warm Homes Nest offers free improvements to eligible low-income households, and ECO4 runs to 31 December 2026.
Sources: Welsh Government: warmer and more energy efficient homes (July 2026); GOV.UK: extending the ECO4 end date, government response.
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 Swansea
- Batts or boards to the specified U-value
- Trays, closers and stop ends as drawn
- Clean-cavity working
- Photo record for building control
Guide prices for Swansea
| 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 Swansea:
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.