Insulation & Exteriors
Insulation for every home — priced by property type.
Lofts, cavities, solid walls, floors and roofs, external wall insulation with K Rend and brick slip, natural materials and commercial roofs. Every service has its own page and a price range for your type of home — with grants and 0% VAT applied where they fit.
- 8 groups, 74 services
- 0% VAT until 31 March 2027
- Prices updated 11 October 2026
Build-up
External wall insulation system
- 1Existing wall
- 2Adhesive and mechanical fixings
- 3Insulation boardEPS, mineral wool, phenolic, wood-fibre or cork
- 4Base coat with glass-fibre mesh
- 5Render or brick slip finish
Eight groups, every service
Everything that keeps the heat in
Loft and roof insulation
Lofts, room-in-roof, pitched and flat roofs, conservatory roofs and spray foam — done safely.
- Loft insulationFrom £400
- Loft insulation top-upFrom £400
- Blown loft insulationFrom £400
- Loft clearance and replacementFrom £900
- Raised loft boarding and storage£600–£1,200 per 10 m²
- Insulated loft hatch and ladders
- Room-in-roof insulationFrom £3,000
- Loft conversion insulation
- Pitched roof insulation from inside£45–£80 per m²
- Warm roof (over-rafter) insulation
- Flat roof warm deck£110–£170 per m²
- Inverted and green flat roofs
- Cold deck flat roof upgrade
- Conservatory roof conversion
- Garage and outbuilding roofs
- Spray foam insulation (open-cell)£1,800–£4,500
- Spray foam removal£2,500–£6,500
Cavity and internal walls
Cavity fill, extraction and refill, wall ties and internal wall insulation for solid walls.
- Cavity wall insulationFrom £800
- Cavity wall extraction and refillFrom £2,500
- Cavity wall tie replacement
- Cavity survey only
- Party wall cavity insulation
- Narrow and hard-to-treat cavities
- Internal wall insulation (IWI)From £5,000
- Breathable IWI for period homesFrom £5,000
- Thin internal liners and aerogel
- Timber frame walls
- Bay, dormer and reveal insulation
External wall insulation and render
Insulation, render and new windows in one contract — certified systems including K Rend and brick slip.
- External wall insulation (EWI)From £9,000
- EWI with brick slip finishFrom £12,000
- K Rend silicone through-coloured renderFrom £4,000
- Monocouche render£50–£85 per m²
- Acrylic and silicone thin coat£50–£85 per m²
- Lime render
- Insulating (thermal) lime render
- Sand and cement, pebbledash and spar dash
- Render repairs, removal and painting
Floors, basements and underfloor heating
Suspended and solid floors, underfloor heating insulation, basements and garage conversions.
- Suspended timber floor insulationFrom £1,200
- Underfloor insulation from the voidFrom £1,200
- Solid floor insulation£60–£110 per m²
- Insulated floor screed£60–£110 per m²
- Underfloor heating insulation£15–£35 per m²
- Floors over garages and open space
- Basement and cellar insulation
- Garage conversion insulation
New build, extension and structural wall systems
ICF, SIPs, timber frame and low-energy build for new homes, extensions and self-builds.
- ICF (insulated concrete formwork)£130–£200 per m²
- SIPs (structural insulated panels)£110–£180 per m²
- Timber frame with insulation
- Cavity wall new build
- Thermal blocks
- Passivhaus and low-energy build
Natural and specialist insulation
Wood-fibre, sheep's wool, hemp, cork and high-performance materials where space or breathability matters.
- Wood-fibre insulation
- Sheep's wool insulation
- Hemp and hemp-lime
- Cellulose (recycled paper)
- Cork board
- Aerogel
- Vacuum insulated panels
- Phenolic (Kingspan Kooltherm)
- XPS
- Multifoil thermal barriers (YBS, Actis)£25–£50 per m²
Airtightness, thermal bridging and finishing
Draught-proofing, airtightness, thermal bridges, acoustic insulation, fire-stopping and ventilation.
- Thermal bridging fixes
- Airtightness works
- Draught-proofingFrom £200
- Pipe, tank and cylinder insulation
- Acoustic insulation
- Fire-stopping and cavity barriers
- Ventilation with insulation£6,000–£10,000
Commercial and industrial insulation
Industrial roofs, commercial flat roofs, non-combustible cladding, dry lining and plant insulation.
- Industrial roof upgrades
- Commercial flat roofs
- Insulated cladding and EWI
- Internal insulation and dry lining
- Pipework and plant insulation
- Cold rooms and controlled spaces
Price by property type
What insulation costs for your home
| Measure | Mid-terrace | Semi / end-terrace | Detached | Bungalow | Flat / block |
|---|---|---|---|---|---|
| Loft insulation (new or top-up) | £500–£1,000 | £600–£1,300 | £900–£1,800 | £900–£2,000 | £400–£900top floor |
| Loft clearance and replacement | £1,200–£2,500 | £1,500–£3,000 | £2,000–£4,000 | £2,000–£4,500 | £900–£2,000 |
| Room-in-roof | £3,500–£7,000 | £4,000–£9,000 | £5,500–£12,000 | £4,500–£9,000chalet | £3,000–£6,000 |
| Cavity wall insulation | £800–£1,500 | £1,200–£2,500 | £2,000–£3,500 | £1,000–£2,000 | £600–£1,200 per flatper flat |
| Cavity extraction and refill | £2,500–£4,500 | £3,500–£7,500 | £6,000–£11,000 | £3,000–£6,000 | Block survey |
| Internal wall insulation (whole home) | £7,000–£14,000 | £10,000–£20,000 | £15,000–£30,000 | £9,000–£18,000 | £5,000–£10,000 |
| External wall insulation + render | £9,000–£15,000 | £14,000–£24,000 | £20,000–£35,000 | £12,000–£20,000 | £130–£220 per m²block |
| EWI with brick slip finish | £12,000–£20,000 | £18,000–£32,000 | £26,000–£45,000 | £16,000–£27,000 | £170–£280 per m² |
| Re-render only (K Rend silicone) | £4,000–£7,500 | £6,500–£12,000 | £9,000–£18,000 | £5,500–£10,000 | £55–£95 per m² |
| Suspended floor insulation | £1,200–£3,000 | £1,500–£4,500 | £2,500–£6,500 | £2,500–£6,000 | £1,200–£3,000ground floor |
| Draught-proofing | £250–£600 | £300–£800 | £450–£1,100 | £300–£800 | £200–£500 |
| Whole-house fabric package | £15,000–£30,000 | £22,000–£45,000 | £35,000–£70,000 | £20,000–£40,000 | Per-block quote |
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.
New-build systems: ICF walls £130–£200 per m² of wall (structure and insulation), SIPs £110–£180 per m² of panel. Natural insulation typically costs 20–50% more than mineral wool. Commercial work is priced per m² after survey.
How it works
Survey, check, install, guarantee
- 1
Survey
A surveyor visits, measures and checks the construction — borescope for cavities, moisture and ventilation for roofs — then confirms what suits your home and the final price.
- 2
Condensation risk and PAS 2035, where needed
Internal and external wall insulation and roof conversions get a condensation risk analysis for each build-up. Funded and whole-house jobs follow PAS 2035, starting with a retrofit assessment.
- 3
Install
We install to the manufacturer's or system holder's specification, with one named contact throughout. Scaffolding, making good and any building control are set out in your quote.
- 4
Guarantee and paperwork
You get the paperwork for what's installed — the guarantee from the relevant body or manufacturer, explained before you sign, plus any building control or competent-person certificates.
Spray foam, done safely
Some lenders and valuers refuse homes with spray foam. We only install certified open-cell systems after an independent suitability assessment — and remove it where it's blocking a sale or remortgage.
How we handle spray foamRender is never sold as insulation
K Rend, monocouche and lime renders renew a wall's finish but don't insulate it. When you're comparing quotes, we show you exactly which is which.
Render without insulationWho we help
Recommendations change with your property
Grants and savings
Funding and 0% VAT that may apply
Grants and savings that may help
- ECO4Closes in 73 days
Up to fully funded; paid by energy suppliers per measure
Grant via local councils (£960m nationally in 2026/27)
- Social Housing Fund
Landlord-led bids
Saves 20% VAT
- Local schemes
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.Questions
Insulation, answered
What's the best insulation for my home?
It depends on your property type. Most homes start with the loft and, where the cavities are empty, the cavity walls — usually the best value. Solid-walled homes look at internal or external wall insulation, and older homes with suspended floors gain from floor insulation. Our EPC planner ranks the options for your home.
How long does insulation take to install?
Loft and cavity insulation are usually done in a day for a typical house. Floors take a few days, internal wall insulation a few days per room, and external wall insulation a few weeks including scaffolding. Your survey confirms the timetable.
Will insulation cause damp or condensation?
Not when the right system is chosen and installed properly. We check ventilation, moisture risk and the wall or roof construction first — with a condensation risk analysis for internal and external wall insulation — and use breathable materials on older solid walls.
Can I get a grant for insulation?
You may. Depending on eligibility, ECO4, Warm Homes: Local Grant, Social Housing Fund and Local schemes can help with insulation costs — based on things like household income, benefits, your home's EPC rating and where you live. Our 60-second checker tells you which you're likely to qualify for; final eligibility is confirmed by the funder or council.
Do I pay VAT on insulation?
Insulation installed in homes in Great Britain is zero-rated for VAT until 31 March 2027, so there's no VAT to add on the insulation itself. Render on its own, and commercial work, are standard-rated.
Begin your project
Price your insulation in two minutes
Choose your measure and property type to see a live price range, with grants and 0% VAT applied where they fit. A survey always confirms the final figure.