Cavity insulation top-up for Caernarfon properties
If your property is in Caernarfon or the LL55 district or nearby Bangor, Porthmadog and Holyhead, it is within our Gwynedd coverage. It is roughly 6 miles south-west of Bangor.
Where a Caernarfon property has an extension or a conservatory, we check how the old and new walls meet, because that junction is often missed. If a wall in Caernarfon 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.
Every elevation is judged on its own exposure. Parts of Gwynedd 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.
For regulations, in Caernarfon filling a cavity is notifiable work under the Building Regulations as they apply in Wales, usually self-certified through a competent person scheme.
Funding in Wales
In Wales, Warm Homes Nest offers free improvements to eligible low-income households, and ECO4 runs to 31 December 2026.
Sources: Welsh Government: warmer and more energy efficient homes (July 2026); GOV.UK: extending the ECO4 end date, government response.
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 Caernarfon
- Borescope survey at several points
- Map of filled and empty sections
- Written result with photos
- Targeted fill with a compatible system
Guide prices for Caernarfon
| 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.
The steps for cavity insulation top-up in Caernarfon:
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.