Cavity insulation for new builds and extensions for Llanelli properties
Llanelli sits in Dyfed, about 14 miles south-east of Carmarthen. We work across the SA15 district, including nearby Ammanford and Carmarthen.
Where a Llanelli 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 Llanelli is usually filled in a single day from outside, with drill holes made good to match the pointing.
Every elevation is judged on its own exposure. Parts of Dyfed 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.
On the rules side, in Llanelli 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 Llanelli
- Clean-cavity working
- Batts or boards to the specified U-value
- Coordination with your bricklayers
- Photo record for building control
Guide prices for Llanelli
| 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 Llanelli:
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.