Cavity insulation top-up for Portsmouth properties
If your property is in Portsmouth or the PO1 district or nearby Gosport, Fareham and Havant, it is within our Hampshire coverage. It is roughly 16 miles south-east of Southampton.
Most Portsmouth 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. Portsmouth properties with rendered or painted walls get a closer look at the outer finish, because cracked render can let rain behind it.
Wind-driven rain is the first thing the surveyor weighs up. 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.
How do I know if my walls need a top-up?
Cold patches on internal walls, a thermal image showing uneven heat loss, or an EPC that says 'filled cavity' when parts of the house feel colder are all signs. Extensions are a common cause: the new wall is insulated as built, but the old wall it joins may have been left partly empty.
What is included in Portsmouth
- Targeted fill with a compatible system
- Borescope survey at several points
- Making good
- Map of filled and empty sections
Guide prices for Portsmouth
| Cavity insulation top-up guide prices | Guide price |
|---|---|
| Detached house | £1,295–£2,295 |
| Semi-detached house | £795–£1,495 |
| End-terrace house | £695–£1,295 |
| Detached bungalow | £695–£1,295 |
| Semi-detached bungalow | £595–£995 |
| Mid-terrace house | £595–£995 |
No VAT is charged on installing insulation in homes until 31 March 2027 (then 5%). 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 Portsmouth:
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.