Cavity insulation for new builds and extensions for Caerphilly properties
We cover Caerphilly and the CF83 postcode district, including nearby Risca, Newport and Cwmbran. It is around 9 miles west of Newport.
A suitable wall in Caerphilly is usually filled in a single day from outside, with drill holes made good to match the pointing. For semi-detached and terraced homes in Caerphilly, cavity barriers are fitted where your wall meets your neighbour's so the fill stays on your side.
Wind-driven rain is the first thing the surveyor weighs up. Parts of Gwent 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.
As for paperwork, in Caerphilly 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.
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 Caerphilly
- Clean-cavity working
- Coordination with your bricklayers
- Photo record for building control
- Batts or boards to the specified U-value
Guide prices for Caerphilly
| 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 Caerphilly 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.