Party wall cavity insulation for Bangor properties
Bangor sits in Gwynedd. We work across the LL57 district, including nearby Caernarfon, Porthmadog and Holyhead.
Most Bangor 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. Where a Bangor property has an extension or a conservatory, we check how the old and new walls meet, because that junction is often missed.
Before any material is chosen, exposure is checked. 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.
In terms of approvals, in Bangor 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.
Why a party wall loses heat
Many semi-detached and terraced homes built with cavity separating walls have that cavity open to the loft. Air moves up the cavity and out at the top, a loss sometimes called the party wall bypass. Filling the cavity and sealing the top stops it.
What is included in Bangor
- Certified fill to the separating wall
- Written result and photos
- Neighbour notification guidance
- Sealing at the top of the cavity
Guide prices for Bangor
| 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 Bangor property:
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.