External wall insulation costs £8,000 to £18,000 for a typical house in 2026. The price depends on wall area, insulation thickness, render or cladding finish, and how complex the installation is. Here's the breakdown.
Cost by house type
| House type | Wall area | Typical cost |
|---|---|---|
| Mid-terrace | 50-60 m² | £6,000-£9,000 |
| Semi-detached | 70-90 m² | £8,000-£13,000 |
| Detached | 130-180 m² | £15,000-£25,000 |
| Bungalow | 60-80 m² | £7,000-£11,000 |
What's included in the cost
A typical external wall insulation quote includes:
- Survey and design
- Insulation boards (usually 100-120mm EPS or mineral wool)
- Fixings (adhesive and mechanical fixings)
- Render (base coat with mesh, top coat)
- Scaffolding (often 20-30% of the total cost)
- Removing and refitting gutters, downpipes, external lights
- Labour (2-4 weeks for most houses)
What affects the price
Scaffolding
Scaffolding costs £800 to £2,000 depending on house size and how long it's needed. Bungalows and single-storey extensions can sometimes use mobile towers instead, which are cheaper.
Render vs cladding
Silicone or mineral render is the cheapest finish (included in the costs above). Timber or fibre-cement cladding costs more (add £2,000 to £5,000). Brick slips (thin brick tiles) cost even more (add £5,000 to £10,000).
Insulation thickness
Most installs use 100mm insulation. Going to 120mm or 150mm adds material cost and makes window reveals more awkward (they need extending). Adds £1,000 to £2,000 to the total cost for marginal thermal benefit.
Complexity
Simple rectangular houses with few windows are cheapest. Houses with bay windows, complex roof lines, lots of external features (porches, canopies), or listed building constraints cost more due to extra detailing work.
How to reduce the cost
Apply for ECO4 grant
If you receive benefits or your household income is under £36,000 and your home has an EPC rating of D or below, you may qualify for free external wall insulation through ECO4. Use the gov.uk Simple Energy Advice tool to check eligibility.
Combine with re-rendering
If your render is failing and needs replacing anyway, adding insulation behind new render is a smaller incremental cost. The scaffolding and labour are already there. You might add £3,000 to £5,000 to a re-render job rather than paying the full £10,000+ for standalone insulation.
Do one wall at a time
Some homeowners insulate the most exposed wall first (often north or west-facing), then do other walls later when budget allows. This spreads the cost but loses some economy of scale (you pay for scaffolding twice).
Is it worth the cost?
External wall insulation saves £200 to £400 per year on heating for a typical solid-wall house. Payback is 20 to 40 years, so it's expensive for the benefit unless you qualify for a grant.
See our full guide on whether external wall insulation is worth it for the complete calculation.