London street of brick townhouses and mansion flats

Who we help · Houses

Townhouse (3–4 storeys)

Usual measures: IWI, roof, glazing, MVHR in modern ones. Watch-out: Scaffolding and access costs.

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Typical prices

Semi / end-terrace prices

Installed, inc. VAT

Internal wall insulation (whole home)£10,000–£20,000
Loft insulation (new or top-up)£600–£1,300
Draught-proofing£300–£800

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Before grants · updated 11 October 2026 · a survey confirms the final figure.

At a glance

Construction, heat loss and watch-outs

Typical construction: Georgian to modern; tall solid or cavity walls
Where heat is lost: Tall walls, roof, stairwell
Usual measures: IWI, roof, glazing, MVHR in modern ones
Watch-outs: Scaffolding and access costs

Recommended

The insulation we usually recommend

With the semi / end-terrace price for each.

Internal wall insulation (IWI)

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

Solid walls where the outside must not changeSemi / end-terrace: £10,000–£20,000

Pitched roof insulation from inside

Insulation between and under the rafters to turn a cold loft into a warm one.

Converting a cold loft to a warm loft£45–£80 per m²

Loft insulation

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

Lofts with little or no insulationSemi / end-terrace: £600–£1,300

Ventilation with insulation

Trickle vents, extract fans, PIV or MVHR so a better-sealed home stays dry.

Every deep retrofit£6,000–£10,000

Draught-proofing

Sealing doors, windows, letterboxes, hatches, floorboards and unused chimneys — every home's quick win.

Every home; quick winSemi / end-terrace: £300–£800

Also from LINX:Windows and doors

Prices

Semi / end-terrace price column

Every insulation measure for this property type, installed and including VAT, before grants.

Insulation price ranges by property type
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.

Price my insulation

Start with a surveyBook a thermal imaging survey — £200–£450, credited against your installation if you go ahead.Book a survey Planning more than one measure?Book a retrofit assessment (pas 2035) — £350–£650, credited against your installation if you go ahead.Book a survey

Grants and savings that may help

ECO4Closes in 73 days
Up to fully funded; paid by energy suppliers per measure
Warm Homes: Local Grant
Grant via local councils (£960m nationally in 2026/27)
Social Housing Fund
Landlord-led bids
0% VAT
Saves 20% VAT
Local schemes
Varies

Check eligibility in 60 seconds

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

Other property types

Begin your project

Price insulation for your townhouse

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.

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