Mineral wool EWI · South Glamorgan
Mineral wool external wall insulation in Penarth
Looking for mineral wool external wall insulation in Penarth? We survey homes across Penarth and the CF64 area, then give you a fixed written price before any work starts. For homes in Penarth near busy roads, mineral wool's sound reduction can be a reason to choose it.
- Free survey in CF64 and nearby
- Guide price from £125 per m² + scaffold, 0% VAT
- Fixed written price before work starts
Free survey in Penarth
Postcode, service and a phone number is all we need.
What's included
- Heavier than EPS, so more fixings and careful handling
- Better sound reduction than foam boards
- Non-combustible board (typically Euroclass A1 or A2-s1,d0 as part of the system)
- Vapour-open, so moisture in solid walls can dry outwards
Before we quote in Penarth
Surveys in Penarth also cover the surrounding CF64 district and towns such as Cardiff and Barry. Penarth is about 3 miles from Cardiff. South Wales has long runs of solid-wall valley terraces, Victorian and Edwardian town housing and post-war council estates.
Exposure to wind-driven rain varies across South Glamorgan: sheltered town streets fare better than walls on high ground or facing the prevailing weather, and the render, beads and cill details are chosen with that in mind.
On blocks and taller buildings in Penarth, mineral wool is the default because of the fire guidance for external walls.
- Postcode district
- CF64
- County or area
- South Glamorgan
- Nation
- Wales
- Nearby
- Cardiff, Barry, Caerphilly, Risca
Approvals in Wales
Householder rules in Wales are similar to England's: in Penarth, a similar-looking finish on a house is often permitted, but conservation areas, flats and listed buildings need permission or consent.
Welsh Building Regulations expect walls to be upgraded when a substantial area is renewed, and building control signs the work off.
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 Penarth
| 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.
How it works
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 Penarth: questions
Does mineral wool get wet?
It is water-repellent and protected by the render system. Like any insulation it must not be left exposed to rain during installation, so boards are covered and work stops in wet weather.
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.
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.
Do you cover Penarth?
Yes — we survey and quote mineral wool external wall insulation in Penarth (CF64) and nearby Cardiff, Barry and Caerphilly, with a fixed written price before any work starts.