External wall insulation · County Down
External wall insulation in Castlereagh
External wall insulation in Castlereagh: free survey, written specification and a fixed price, with the details that keep walls dry planned from the start. We plan EWI in Castlereagh around the details that cause trouble later — cills, eaves, downpipes and the base of the wall above the damp-proof course.
- Free survey in BT5 and nearby
- Guide price from £105 per m² + scaffold, 0% VAT
- Fixed written price before work starts
Free survey in Castlereagh
Postcode, service and a phone number is all we need.
What's included
- Work happens outside, so you can live at home throughout
- Typically takes a 225mm solid brick wall from around 2.1 W/m²K to about 0.30 W/m²K with 90–110mm of board
- Boards chosen for the wall: EPS, mineral wool, wood fibre or phenolic
- Cills, pipes, vents, meter boxes and the roofline detailed as part of the job
Castlereagh: walls, weather and approvals
Surveys in Castlereagh also cover the surrounding BT5 district and towns such as Belfast and Holywood. It's roughly 11 miles from Castlereagh to Bangor (County Down), the largest town in County Down. Northern Ireland has many rendered and pebble-dashed homes, older solid-walled rural houses, and estates built by the Housing Executive.
Exposure to wind-driven rain varies across County Down: 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 Castlereagh; a cold gable or rear wall can be done on its own where it suits.
- Postcode district
- BT5
- County or area
- County Down
- Nation
- Northern Ireland
- Nearby
- Belfast, Holywood, Newtownabbey, Lisburn
Planning and building control in Northern Ireland
In Northern Ireland, permitted development is set by the 2015 Order; in Castlereagh, changing a house's external appearance, and any work on flats or listed buildings, may need permission, so we check with the council.
External wall insulation is building work under the Building Regulations (Northern Ireland) 2012, so council building control is involved, with Technical Booklet F1 covering dwellings.
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 Castlereagh
| 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 Castlereagh: questions
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.
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.
Do you cover Castlereagh?
Yes — we survey and quote external wall insulation in Castlereagh (BT5) and nearby Belfast, Holywood and Newtownabbey, with a fixed written price before any work starts.