Cavity insulation for new builds and extensions for Derry properties
Derry sits in County Londonderry. We work across the BT48 district, including nearby Limavady, Coleraine and Magherafelt.
Derry properties with rendered or painted walls get a closer look at the outer finish, because cracked render can let rain behind it. Most Derry houses built from the 1920s onwards have cavity walls, but the survey still checks each one: cavity width, debris, the condition of the brickwork and how exposed each wall is.
Local weather affects which walls can be filled. Parts of County Londonderry 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 Derry inserting cavity wall insulation needs a building control application to the council before work starts.
Funding in Northern Ireland
In Northern Ireland, the Affordable Warmth Scheme helps eligible households with a gross income under £23,000.
Sources: NI Housing Executive: Affordable Warmth Scheme; Utility Regulator: NI Sustainable Energy Programme.
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 Derry
- Trays, closers and stop ends as drawn
- Clean-cavity working
- Photo record for building control
- Batts or boards to the specified U-value
Guide prices for Derry
| 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 Derry:
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.