Insulation · Group D
Floors, basements and underfloor heating — no more cold feet.
Suspended and solid floors, underfloor heating insulation, basements and garage conversions.
Build-up
Suspended timber floor
Room
Ventilated void
- 1Floorboards
- 2Airtight membrane
- 3Insulation between the joists
- 4Netting or battens
- 5Ventilated void — air bricks kept clear
Overview
About floors, basements and underfloor heating
Draughty suspended floors and cold solid floors are one of the most noticeable comfort problems in older homes. Insulating between the joists with an airtight membrane — or from below where there's a deep enough void — stops the draughts and the heat loss together.
Solid floors, screeds and underfloor heating insulation are best done when floors are coming up anyway: during a renovation, an extension or a kitchen refit. We also insulate basements, rooms over garages and garage conversions.
Every service in group D
8 ways we can help
Suspended timber floor insulation
Mineral wool or rigid board between the joists with an airtight membrane.
Underfloor insulation from the void
Insulation fitted from below through a crawl space, without lifting floorboards.
Solid floor insulation
PIR or XPS boards over the slab with a new screed or floating floor.
Insulated floor screed
Insulation plus screed, ready for underfloor heating.
Underfloor heating insulation
Insulation boards under wet or electric UFH so heat goes up, not into the ground.
Floors over garages and open space
Insulating floors over unheated garages, passages, undercrofts and overhangs.
Basement and cellar insulation
Insulating basement walls and floors with tanking or cavity drain membranes.
Garage conversion insulation
Floor, walls and roof brought up to habitable standard.
Prices
What floors and basements costs
| Measure | Mid-terrace | Semi / end-terrace | Detached | Bungalow | Flat / block |
|---|---|---|---|---|---|
| Suspended floor insulation | £1,200–£3,000 | £1,500–£4,500 | £2,500–£6,500 | £2,500–£6,000 | £1,200–£3,000ground floor |
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.
| Service | Typical range, installed |
|---|---|
| Solid floor insulation with new screed | £60–£110 per m² |
| Underfloor heating insulation boards (laid with UFH) | £15–£35 per m²extra |
Indicative ranges for London and the South East, supplied and installed, including VAT. Updated 11 October 2026. A survey confirms your final price.
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.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.
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.
Grant schemes change often. Our 60-second checker uses the current rules and tells you plainly whether you're likely, possibly or not eligible — and we never call funded work free without saying it depends on eligibility.
Check my eligibilityQuestions
Floors and Basements: common questions
Is floor insulation worth it?
For draughty suspended timber floors, usually yes — it cuts heat loss and draughts and makes rooms noticeably more comfortable. Solid floors are best insulated during a renovation, when the floor is coming up anyway.
Can floors be insulated without lifting the floorboards?
Sometimes. If the void under the floor is deep enough to work in safely, insulation can be fitted from below. We check the void at survey.
Does floor insulation stop the void being ventilated?
No — it must not. Air bricks are kept clear so the void stays dry and the joists stay sound; the insulation sits between the joists with an airtight membrane above.
Begin your project
Price your insulation in two minutes
Prices by property type, with grants and 0% VAT applied where they fit. A survey always confirms the final figure.