Mineral wool EWI · South Glamorgan
Mineral wool external wall insulation in Cardiff
Quotes for mineral wool external wall insulation in Cardiff list the system, the detailing and the VAT position in writing, so you know exactly what's included. On blocks and taller buildings in Cardiff, mineral wool is the default because of the fire guidance for external walls.
- Free survey in CF10 and nearby
- Guide price from £125 per m² + scaffold, 0% VAT
- Fixed written price before work starts
Free survey in Cardiff
Postcode, service and a phone number is all we need.
What you get
- Non-combustible board (typically Euroclass A1 or A2-s1,d0 as part of the system)
- Used on blocks of flats and buildings with storeys above 11m
- Finished in mineral or silicone render, or brick slip
- Better sound reduction than foam boards
What we look for in Cardiff
Surveys in Cardiff also cover the surrounding CF10 district and towns such as Penarth and Caerphilly. 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.
Older solid-walled homes in Cardiff can suit a vapour-open mineral wool build-up better than foam; the survey checks the wall first.
- Postcode district
- CF10
- County or area
- South Glamorgan
- Nation
- Wales
- Nearby
- Penarth, Caerphilly, Barry, Risca
Permissions in Wales
Householder rules in Wales are similar to England's: in Cardiff, 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.
What about noise?
Dense mineral wool adds mass and absorbs sound, so homes beside main roads or railways often notice a quieter interior, particularly where windows are also upgraded. The improvement depends on the whole wall and windows, so we don't quote decibel figures without testing.
Mineral wool external wall insulation prices in Cardiff
| 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.
What happens next
Get a guide price
Try the online quote tool for a ballpark figure.
Book the survey
A visit at a time that suits you.
Agree the quote
Nothing starts until you've signed the written price.
We do the work
Planned around weather, with you kept informed.
Mineral wool EWI in Cardiff: questions
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.
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.
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.
Do you cover Cardiff?
Yes — we survey and quote mineral wool external wall insulation in Cardiff (CF10) and nearby Penarth, Caerphilly and Barry, with a fixed written price before any work starts.