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Usual measures: EWI or IWI on gable, loft, floor, room-in-roof. Watch-out: Gable wall is the main loss.
Typical prices
Semi / end-terrace prices
Before grants · updated 11 October 2026 · a survey confirms the final figure.
Read the full guide: Semi-detached homes
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Recommended

A complete certified build-up of insulation board, mesh and render from one system holder.

Insulated plasterboard or stud systems fitted inside solid walls where the outside must not change.

Mineral wool laid between and across the joists to 270–300 mm so heat stays in the rooms below.

Mineral wool or rigid board between the joists with an airtight membrane.

Insulating the sloping ceilings, stud walls, flat ceiling, gables and dormer cheeks of an attic room.

A borescope survey, then blown mineral wool or bonded bead injected into empty cavity walls.
Prices
| Measure | Semi / end-terrace |
|---|---|
| Loft insulation (new or top-up) | £600–£1,300 |
| Loft clearance and replacement | £1,500–£3,000 |
| Room-in-roof | £4,000–£9,000 |
| Cavity wall insulation | £1,200–£2,500 |
| Cavity extraction and refill | £3,500–£7,500 |
| Internal wall insulation (whole home) | £10,000–£20,000 |
| External wall insulation + render | £14,000–£24,000 |
| EWI with brick slip finish | £18,000–£32,000 |
| Re-render only (K Rend silicone) | £6,500–£12,000 |
| Suspended floor insulation | £1,500–£4,500 |
| Draught-proofing | £300–£800 |
| Whole-house fabric package | £22,000–£45,000 |
Indicative ranges for London and the South East, supplied and installed, including VAT, before grants. Updated 11 October 2026. A survey confirms your final price.
Up to fully funded; paid by energy suppliers per measure
Grant via local councils (£960m nationally in 2026/27)
Landlord-led bids
Saves 20% VAT
Varies
Eligibility depends on your circumstances and is confirmed by evidence and the funder or council.
0% VAT on energy-saving materials
Insulation, solar panels, batteries and heat pumps installed in homes in Great Britain are zero-rated for VAT until 31 March 2027. Windows and doors are not included.Houses
Begin your project
See a price range for your property type in two minutes, with grants and 0% VAT applied where they fit. A survey always confirms the final figure.