External wall insulation · South Glamorgan
External wall insulation in Penarth
Quotes for external wall insulation in Penarth list the system, the detailing and the VAT position in writing, so you know exactly what's included. Whole-house jobs and single elevations are both quoted in Penarth; a cold gable or rear wall can be done on its own where it suits.
- Free survey in CF64 and nearby
- Guide price from £105 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 you get
- Boards chosen for the wall: EPS, mineral wool, wood fibre or phenolic
- Covers tired brick, pebble dash or failing render with a new finish
- Typically takes a 225mm solid brick wall from around 2.1 W/m²K to about 0.30 W/m²K with 90–110mm of board
- Cills, pipes, vents, meter boxes and the roofline detailed as part of the job
What we look for in Penarth
Surveys in Penarth also cover the surrounding CF64 district and towns such as Cardiff and Barry. Penarth sits around 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.
We plan EWI in Penarth around the details that cause trouble later — cills, eaves, downpipes and the base of the wall above the damp-proof course.
- Postcode district
- CF64
- County or area
- South Glamorgan
- Nation
- Wales
- Nearby
- Cardiff, Barry, Caerphilly, Risca
Permissions 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.
Building control in Wales applies to most insulation and re-rendering jobs of this size; the quote states who submits the notice.
How does external wall insulation work?
Heat moves out through a wall faster when the wall is solid or poorly insulated. EWI wraps the outside face in a continuous layer of insulation, so the masonry stays on the warm side and the cold bridges at floor and party-wall junctions are reduced. The boards are bonded with adhesive and, on most walls, mechanically fixed. A base coat with an embedded glass-fibre mesh goes over the top, then a primer and the decorative finish.
Because the wall itself sits inside the insulation, it stays warmer and drier, and the rooms keep their full size. That is the main difference from internal insulation.
External wall insulation prices in Penarth
| 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.
How it works
Enquiry
Send your postcode and a few details.
Measured survey
Walls, damp, eaves, cills and services recorded.
Written price
A fixed price with the specification attached.
Work and handover
Installed, inspected and documents handed over.
External wall insulation in Penarth: questions
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.
Does external wall insulation cause damp?
Not when it is specified and detailed properly. Problems usually come from poor detailing: no starter track above the damp-proof course, gaps at cills and penetrations, or a vapour-closed system on a wall that needs to breathe. The survey checks moisture, ground levels and the wall type before a system is chosen.
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 Penarth?
Yes — we survey and quote external wall insulation in Penarth (CF64) and nearby Cardiff, Barry and Caerphilly, with a fixed written price before any work starts.