Cavity wall insulation 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 around 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.
Exposure matters for every cavity wall. 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.
For regulations, 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 happens on the day?
Holes of around 22mm are drilled in the mortar joints in a set pattern, roughly a metre apart. The insulation is blown in from the bottom up until each section is full, then every hole is filled with colour-matched mortar. Air bricks and flues are protected, and a cavity barrier is fitted where your wall joins a neighbour's.
What is included in Portsmouth
- Suitability survey with photos and a written result
- Building regulations route for your nation, confirmed in writing
- Borescope check where the cavity is in doubt
- Cavity barriers at party walls
Guide prices for Portsmouth
| Cavity wall insulation guide prices | Guide price |
|---|---|
| Detached house | £2,295–£3,795 |
| Semi-detached house | £1,495–£2,495 |
| End-terrace house | £1,295–£2,195 |
| Detached bungalow | £1,295–£2,195 |
| Semi-detached bungalow | £895–£1,595 |
| Mid-terrace house | £795–£1,395 |
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.
From enquiry to finish 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.