External wall insulation · South Glamorgan
External wall insulation in Cardiff
We quote external wall insulation for homes in Cardiff (CF10) and nearby Penarth and Caerphilly, with guide prices online and a free survey to fix the price. For homes in Cardiff, the survey starts with the wall itself: solid brick, stone or concrete, and whether any old render is sound enough to insulate over.
- Free survey in CF10 and nearby
- Guide price from £105 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's included
- Covers tired brick, pebble dash or failing render with a new finish
- Cills, pipes, vents, meter boxes and the roofline detailed as part of the job
- Work happens outside, so you can live at home throughout
- Installing wall insulation in homes is currently zero-rated for VAT until 31 March 2027
Before we quote in Cardiff
We also cover Penarth and Caerphilly, close to 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.
Whole-house jobs and single elevations are both quoted in Cardiff; a cold gable or rear wall can be done on its own where it suits.
- Postcode district
- CF10
- County or area
- South Glamorgan
- Nation
- Wales
- Nearby
- Penarth, Caerphilly, Barry, Risca
Wales: planning and regulations
For homes in Cardiff, the local planning authority decides any borderline cases; changing a brick house to render, or work on flats, usually needs an application in Wales.
Building control in Wales applies to most insulation and re-rendering jobs of this size; the quote states who submits the notice.
Which homes is EWI suited to?
EWI is mainly used on solid-walled houses (most homes built before about 1920), on post-war concrete and steel-framed houses, on homes where cavity fill isn't possible, and on bungalows and park homes. It also suits flats and blocks where the whole building is treated at once.
It is less straightforward where the walls face a pavement with no room to project, on listed buildings, or where planning rules want the existing brick or stone left visible. A survey picks these up before you commit.
External wall insulation prices in Cardiff
| Item | Guide price | Notes |
|---|---|---|
| EPS system with silicone render | £105–£145 per m²0% VAT | Most common choice for houses |
| Mineral wool system | £125–£170 per m²0% VAT | Non-combustible, vapour-open |
| Brick-slip finish over insulation | £185–£260 per m²0% VAT | Where a brick look is wanted |
| Three-bed semi, EPS + silicone (incl. scaffold) | £10,200–£17,7000% VAT | 80–100 m² of wall; depends on detailing and access |
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.
External wall insulation in Cardiff: questions
Does EWI need Building Regulations approval?
In England and Wales, usually. Insulating more than half of a wall's area, or more than a quarter of the building's whole external envelope, counts as renovating a thermal element, so building control needs to be involved and the wall should reach about 0.30 W/m²K where that's practical. Scotland and Northern Ireland have their own building standards processes.
How much does external wall insulation cost?
Our guide price for EWI is £105–£170 per m² of wall depending on the system, plus scaffolding. A typical three-bed semi with EPS and silicone render comes to roughly £10,200–£17,700 for the whole house, including scaffold. Installing insulation in a home is zero-rated for VAT until 31 March 2027, so that's the total. You get a fixed written price after a free survey.
How long does external wall insulation last?
A well-installed render system is commonly expected to last 25–30 years or more, with occasional cleaning and inspection of sealants. The system manufacturer's documentation states the expected service life for the specific build-up.
Do you cover Cardiff?
Yes — we survey and quote external wall insulation in Cardiff (CF10) and nearby Penarth, Caerphilly and Barry, with a fixed written price before any work starts.