Cavity insulation for new builds and extensions for Portsmouth properties
Portsmouth sits in Hampshire, roughly 16 miles south-east of Southampton. We work across the PO1 district, including nearby Gosport, Fareham and Havant.
If a wall in Portsmouth 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. Portsmouth properties with rendered or painted walls get a closer look at the outer finish, because cracked render can let rain behind it.
Every elevation is judged on its own exposure. Hampshire has a mix of moderate and more exposed sites. Hilltop, coastal and west-facing walls take the brunt of wind-driven rain, so the survey records exposure for each elevation before a material is chosen.
On the rules side, in Portsmouth 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.
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 Portsmouth
- Trays, closers and stop ends as drawn
- Batts or boards to the specified U-value
- Clean-cavity working
- Coordination with your bricklayers
Guide prices for Portsmouth
| 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 Portsmouth property:
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.