Mineral wool EWI · Gwynedd
Mineral wool external wall insulation in Caernarfon
We quote mineral wool external wall insulation for homes in Caernarfon (LL55) and nearby Llangefni and Bangor (Gwynedd), with guide prices online and a free survey to fix the price. On blocks and taller buildings in Caernarfon, mineral wool is the default because of the fire guidance for external walls.
- Free survey in LL55 and nearby
- Guide price from £125 per m² + scaffold, 0% VAT
- Fixed written price before work starts
Free survey in Caernarfon
Postcode, service and a phone number is all we need.
Included as standard
- Finished in mineral or silicone render, or brick slip
- Non-combustible board (typically Euroclass A1 or A2-s1,d0 as part of the system)
- Heavier than EPS, so more fixings and careful handling
- Used on blocks of flats and buildings with storeys above 11m
Local considerations in Caernarfon
Surveys in Caernarfon also cover the surrounding LL55 district and towns such as Llangefni and Bangor (Gwynedd). It's roughly 8 miles from Caernarfon to Bangor (Gwynedd), the largest town in Gwynedd. North Wales has many solid stone and slate-built homes, Victorian seaside terraces and post-war council estates.
Parts of Gwynedd fall in the higher wind-driven rain exposure bands, especially coastal and upland sites, so render specification, movement joints and detailing at cills, verges and the base of the wall matter more than usual.
For homes in Caernarfon near busy roads, mineral wool's sound reduction can be a reason to choose it.
- Postcode district
- LL55
- County or area
- Gwynedd
- Nation
- Wales
- Nearby
- Llangefni, Bangor (Gwynedd), Holyhead, Llandudno
Permissions in Wales
Householder rules in Wales are similar to England's: in Caernarfon, a similar-looking finish on a house is often permitted, but conservation areas, flats and listed buildings need permission or consent.
In Wales, insulating or re-rendering more than half of a wall's area is treated as renovating a thermal element under Approved Document L (Wales), so building control is involved before work starts.
Wales applies its own external wall fire rules, updated in 2025; on taller residential buildings we specify non-combustible mineral wool systems.
Why choose mineral wool over EPS?
Two reasons come up most: fire and moisture. Mineral wool doesn't burn, which is why guidance for taller residential buildings points to non-combustible external wall materials. It is also vapour-open, so a solid wall that holds some moisture can keep drying outwards through the insulation and render.
The trade-offs are weight and cost. Slabs are denser, need more fixings and take longer to install, so the price per m² is higher than EPS.
Mineral wool external wall insulation prices in Caernarfon
| Item | Guide price | Notes |
|---|---|---|
| Mineral wool + mineral or silicone render | £125–£170 per m²0% VAT | Excluding scaffold |
| Mineral wool + brick slip | £195–£260 per m²0% VAT | Heavier slip systems need extra fixings |
| Three-bed semi, full house | £11,800–£20,2000% VAT | 80–100 m² of wall, including scaffold |
Confirmed by a fixed written quote after survey. 0% VAT: installing insulation in a home is zero-rated until 31 March 2027, so these figures are the total; 5% applies from 1 April 2027.
From enquiry to finished wall
Tell us about the property
Use the quote tool or form, or call. Photos help.
Free survey
We measure, check the walls and confirm approvals.
Fixed written quote
System, details, access, exclusions and VAT in writing.
Installation
Scheduled for suitable weather, with a clear programme.
Mineral wool EWI in Caernarfon: questions
Is mineral wool needed for a bungalow?
Rarely for fire reasons. It may still be chosen on a damp-prone solid wall where a vapour-open build-up is wanted.
Is mineral wool better than EPS?
Not always better — different. Mineral wool wins on fire performance, breathability and acoustics; EPS wins on cost, weight and thinner boards for the same U-value. The wall, the building height and your priorities decide it.
Can mineral wool EWI have a brick finish?
Yes. Brick slips can be bonded over mineral wool systems designed for them, with additional fixings for the extra weight.
Do you cover Caernarfon?
Yes — we survey and quote mineral wool external wall insulation in Caernarfon (LL55) and nearby Llangefni, Bangor (Gwynedd) and Holyhead, with a fixed written price before any work starts.