Independent costs, scores and savings data for external wall insulation in the UK. Free comparison tool and local installer matching.
External wall insulation (EWI) is the primary solution for solid-walled homes built before 1920 that have no cavity. Insulation boards are fixed to the outside of the property and covered with render or cladding. Higher upfront cost but comprehensive thermal improvement.
| Factor | Detail |
|---|---|
| Our Independent Score | 7.0/10 |
| Typical Cost (semi-det) | £6,000–£15,000 |
| Annual Energy Saving | £200–£400/yr |
| Payback Period | 20–30 years |
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