Party wall cavity insulation for Caerphilly properties
Caerphilly is among the towns we cover in Gwent, alongside Risca, Newport and Cwmbran. It is around 9 miles west of Newport.
A suitable wall in Caerphilly is usually filled in a single day from outside, with drill holes made good to match the pointing. If a wall in Caerphilly 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.
Local weather affects which walls can be filled. Parts of Gwent 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.
On the rules side, in Caerphilly 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.
What we need from you and your neighbour
The cavity is shared, so we talk you through notifying your neighbour before work. Filling is done from your side, usually through the loft. The survey confirms the wall is a cavity wall and not solid masonry, and checks for cables, flues and any gaps that would let fill escape.
What is included in Caerphilly
- Loft inspection and borescope check
- Written result and photos
- Certified fill to the separating wall
- Neighbour notification guidance
Guide prices for Caerphilly
| Party wall cavity insulation guide prices | Guide price |
|---|---|
| Party wall, two-storey house | £595–£895 |
| Party wall, bungalow | £395–£695 |
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 Caerphilly 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.