External wall insulation · England
External wall insulation in Wiltshire
External wall insulation across Wiltshire: measured survey, clear specification and a fixed written price before any work starts. We plan EWI in Wiltshire around the details that cause trouble later — cills, eaves, downpipes and the base of the wall above the damp-proof course.
- Free survey and fixed written price
- Guide price from £105 per m² + scaffold, 0% VAT
- Planning and building control checked for England
Free survey in Wiltshire
Tell us the postcode and what you need.
What the job covers
- 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
- Boards chosen for the wall: EPS, mineral wool, wood fibre or phenolic
- Typically takes a 225mm solid brick wall from around 2.1 W/m²K to about 0.30 W/m²K with 90–110mm of board
- Installing wall insulation in homes is currently zero-rated for VAT until 31 March 2027
Homes and walls in Wiltshire
The South West has many stone and solid-walled cottages, exposed coastal properties and a share of post-war system-built houses, including types such as the Cornish Unit.
Exposure to wind-driven rain varies across Wiltshire: 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 Wiltshire; a cold gable or rear wall can be done on its own where it suits.
- Nation
- England
- Region
- South West
- Towns covered
- Swindon, Salisbury, Trowbridge, Chippenham
- Guide price
- From £105 per m² + scaffold · 0% VAT
England: planning and regulations
For houses, external wall insulation and render are often permitted development where the finish looks similar to the existing walls. Planning permission is usually needed in conservation areas, National Parks, National Landscapes, the Broads and World Heritage Sites (where cladding a house in stone, artificial stone, pebble dash, render, timber, plastic or tiles isn't permitted development), for flats and maisonettes, for commercial buildings, under an Article 4 direction, or where the look changes noticeably. Listed buildings need listed building consent.
Renovating more than half of a wall's area — insulating it, or stripping and re-rendering it — or more than a quarter of the building's whole external envelope brings in the energy requirements of Part L, so building control needs to be involved and the wall should reach about 0.30 W/m²K where that's technically, functionally and economically feasible.
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 Wiltshire
| 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
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 Wiltshire: 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.
Can EWI go over pebble dash?
Usually yes. The dash is tested for adhesion and hollow areas; sound dash can be insulated over with additional mechanical fixings, while loose areas are removed first.
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.
Do you cover all of Wiltshire?
Yes. We survey and quote external wall insulation across Wiltshire, including Swindon, Salisbury, Trowbridge, Chippenham.
Do I need planning permission in England?
For houses, external wall insulation and render are often permitted development where the finish looks similar to the existing walls. We check your address before quoting.