Cavity insulation top-up across West Glamorgan
We cover 4 towns in West Glamorgan: Swansea, Neath, Briton Ferry and Gorseinon.
Every elevation is judged on its own exposure. Parts of West Glamorgan 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.
If a wall in West Glamorgan 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. Most West Glamorgan 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.
Building Regulations in Wales
In Wales, filling an existing cavity is also notifiable building work under the Building Regulations as they apply in Wales. A registered installer normally self-certifies it through a competent person scheme; otherwise a building notice goes to your council's building control before work starts. Welsh rules can differ from England's, so the notification route is confirmed in writing on your quote.
Funding in Wales
- Warm Homes Nest offers free improvements, including insulation, to eligible low-income owner-occupiers and private renters; eligibility was widened to some households without means-tested benefits.
- Green Homes Wales has been piloting advice and interest-free loans for households above the Nest and ECO4 income thresholds.
- ECO4 runs until 31 December 2026 across Great Britain, including Wales.
Sources: Welsh Government: building work competent person schemes; CIGA: CWISC competent person scheme; Welsh Government: issues arising from cavity wall insulation installations; Welsh Government: warmer and more energy efficient homes (July 2026); GOV.UK: extending the ECO4 end date, government response.
When a top-up is not enough
If the existing fill is wet, contaminated with debris or breaking down, adding more on top can make things worse. In that case we tell you the honest option, which may be partial or full removal and refill.
What is included
- Borescope survey at several points
- Map of filled and empty sections
- Targeted fill with a compatible system
- Making good
- Written result with photos
Cavity insulation top-up prices in West Glamorgan
| 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.
What happens next for a West Glamorgan 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.