Heating · Updated 2026
Solid wall insulation cost
Typical range£1,500–£30,000· Average external wall insulation (semi-detached)
Internal and external solid wall insulation costs for 2025. In the UK, expect to pay between £1,500 and £30,000, with the typical project around £13,000 (average external wall insulation (semi-detached)). Regional variation, specification tier and site access conditions all shift the final quote.
Quick answer: Solid wall insulation cost in the UK typically costs between £1,500 and £30,000 (Average external wall insulation (semi-detached)). London and the South East run 20–35% above this range; the North, Wales and most of Scotland sit 5–15% below.
Homeowners researching this typically also price up cavity wall insulation cost and loft insulation cost. For wider context, browse our bathroom pricing, kitchen pricing and trades day rates.
Cost table
Indicative price ranges (UK, GBP)
| Item | Typical range (GBP) |
|---|---|
Internal wall insulation (one room) — Dot & dab or frame system on one wall | £1,500–£4,000 |
Internal insulation (whole house) — All external-facing walls, full house | £6,000–£18,000 |
External wall insulation (semi) — EWI with render finish, 3 walls | £8,000–£18,000 |
External wall insulation (detached) — Full house EWI, all four walls | £12,000–£30,000 |
Labour costs
Labour typically accounts for 55% of the total project cost in the UK.
Labour line items
| Item | Typical range (GBP) |
|---|---|
EWI installer (scaffold incl.) | £0–£0 |
Internal board fix (per m²) | £15–£35/m² |
Plaster skim finish | £10–£20/m² |
Making good (windows etc.) | £500–£2,000 |
Materials costs
Materials and fittings make up the remainder of the budget, with specification tier driving most of the variation.
Materials & fittings
| Item | Typical range (GBP) |
|---|---|
EPS insulation board (per m²) | £8–£18/m² |
Mineral wool board (per m²) | £12–£25/m² |
Render system (EWI) | £15–£35/m² |
Internal PIR board (per m²) | £12–£25/m² |
Vapour barrier | £3–£8/m² |
Factors affecting cost in the UK
- ·Region — London and the South East run 15–30% above national averages.
- ·Specification tier — premium materials and finishes can double the base cost.
- ·Access and site conditions — flats, restricted parking and listed buildings add time.
- ·Scope changes mid-project — late design decisions are the biggest cost overrun driver.
- ·Trade availability — quotes rise 10–20% in peak spring and summer months.
Ways to reduce cost
- ·Choose internal solid wall insulation for individual rooms; external for whole house.
- ·Phase external insulation with a planned re-render to share scaffold cost.
- ·Check ECO4 and Great British Insulation Scheme grants before paying full price.
- ·Specify EPS or mineral wool boards over phenolic for a 25–40% material saving.
- ·Use a TrustMark-registered installer to qualify for grants and 25-year guarantees.
Frequently asked questions
- How much can solid wall insulation save?
- Solid wall insulation can save £300–£600/year in a typical semi-detached home, compared to an uninsulated solid wall. Heat loss through solid walls accounts for ~35% of the total in an uninsulated Victorian home.
- Internal or external insulation — which is better?
- External wall insulation (EWI) is generally superior: it doesn't reduce internal room size, eliminates cold bridges, and can transform the external appearance. Internal is cheaper and doesn't require scaffold but reduces room dimensions by 80–120mm per wall.
- Is there a grant for solid wall insulation?
- Yes — the ECO4 scheme and Great British Insulation Scheme both fund solid wall insulation for eligible households. Funding can cover the full cost in some cases. Check gov.uk or your energy supplier.