Floor insulation in London costs a median of £4,320 per home, with half of all jobs falling between £2,900 and £6,700. The per square metre rate is typically £76 to £110, median £83, for a suspended timber floor insulated from above. Those figures come from 59 priced floor quotes in our own quote book, not a national average.
Key takeaways
- Median floor insulation job in London and the South-East: £4,320 (59 quotes, 2025 to 2026).
- Half of all jobs cost between £2,927 and £6,705; the cheapest was just over £1,000 and the largest £14,253.
- Per m² rate: median £83, typically £76 to £110, range £55 to £160.
- Suspended timber floors from below (a cellar or crawl space) are the cheapest route because no floorboards come up.
- Solid floors cost more per m² because the floor build-up, screed and finishes have to come out or the floor level rises.
- Installation is 0% VAT until 31 March 2027 as an energy-saving material.
What floor insulation really costs
These are the priced floor insulation quotes we issued across London, Surrey, Kent and Hertfordshire, taken from our quote system on 2 August 2026. They include labour, materials, membranes, rubbish clearance and VAT at 0%. They exclude any extras the customer added, such as new flooring on top.
| Measure | Value | What it tells you |
|---|---|---|
| Priced floor projects | 59 | The sample behind every number here |
| Median project price | £4,320 | Half of homes paid less, half paid more |
| Middle half of projects | £2,927 to £6,705 | Where a typical 2 or 3 bed ground floor lands |
| Smallest and largest | £1,016 to £14,253 | One room up to a whole large ground floor |
| Per m² rate (42 jobs) | median £83 | Suspended timber floor, insulated from above |
| Middle half of rates | £76 to £110 per m² | Higher end: solid floors and awkward access |
For a quick estimate, measure the ground floor rooms that sit over a void or over the ground and multiply by £83. A 45 m² ground floor comes out at about £3,700; a 60 m² floor at about £5,000. Then add or subtract for the factors below.
Suspended timber floor insulation cost
Most London homes built before 1950 have a suspended timber ground floor: boards on joists over a void, with air bricks in the outside wall. Cold air moves through that void all winter and the floor is often the coldest surface in the house.
From above (boards lifted)
We lift the floorboards, fit a breather membrane or support netting between the joists, lay mineral wool or PIR board between them, and put the boards back. This is the standard method and the one behind the £83 per m² median. It adds a day or two per room because furniture, carpets and boards all come up.
From below (cellar or crawl space)
If there is a cellar or enough crawl space, the insulation goes in from underneath and nothing upstairs moves. Materials are the same, labour is lower, and there is no making good. Typical rates sit at the lower end of the range, around £70 to £85 per m². Ask about this first; it is the route people forget.
Solid floor insulation cost
Concrete ground floors, common from the 1950s and in every extension, are insulated either on top (rigid board and a new floor finish, which raises the floor by 60 to 120 mm) or by breaking out the slab and rebuilding it with insulation underneath. The first costs less but takes height; the second is a building job.
| Method | Indicative rate | Notes |
|---|---|---|
| Insulate on top of the slab | £80 to £120 per m² | Rigid PIR or phenolic board, new floor finish on top, doors trimmed |
| Break out and re-lay the slab | £150 to £250 per m² | Only when the floor is being replaced anyway |
| Kitchen or bathroom floors | Quoted separately | Units, sanitaryware and services add cost |
The upper part of our rate range, £110 to £160 per m², is almost entirely solid floor work and rooms with fitted kitchens.
What pushes the price up or down
- Access. From below is cheapest; lifting fitted floors, laminate or tiles is dearest.
- Floor area. Small jobs carry the same set-up cost, so one room costs more per m² than a whole ground floor.
- Material. Mineral wool between joists is the standard; PIR board gives more insulation per centimetre where joists are shallow, at a higher material cost.
- Condition. Rotten joists, damp voids or missing air bricks need fixing first. We price the repair as its own line.
- Finishes. Putting carpet, laminate or engineered wood back, or fitting new, is quoted separately.
Is floor insulation worth it?
An uninsulated ground floor loses roughly 10 to 15% of a home's heat, more in a draughty suspended floor. The Energy Saving Trust puts the saving from insulating a suspended floor at around £50 to £100 a year for a typical house, which on its own is a long payback. The reason people do it is comfort: the floor stops feeling cold underfoot, draughts through the skirting stop, and the room reaches temperature faster.
It also matters for an EPC and for a heat pump. Floor insulation is one of the few measures that improves an EPC score cheaply on a solid wall house where external insulation is not an option, and a heat pump running at low flow temperatures needs every surface to hold heat. See do I need to insulate before a heat pump.
How we quote a floor
- Free survey: we lift a board or look from below, check the void depth, joist size, ventilation and any damp.
- Fixed written quote within 24 hours, priced per room with the method, material and thickness stated.
- Installation, usually one to three days for a whole ground floor, with rooms done one at a time so you can stay in.
- Written guarantee and Building Regulations certificate where the work needs one.
Every figure on this page is from real quotes, but every floor is different. The floor insulation service page has the full method detail, and the London insulation price report shows how floors compare with walls and lofts.
Frequently asked questions
How much does it cost to insulate a suspended timber floor?
From our quote book, a median of £83 per m² when insulated from above with the boards lifted, typically £76 to £110. A 3 bed ground floor of 45 to 60 m² comes to £3,700 to £5,000. From below, where there is a cellar or crawl space, it is cheaper.
How much does solid floor insulation cost?
Insulating on top of an existing concrete slab costs around £80 to £120 per m² including a new floor finish. Breaking out and re-laying the slab with insulation underneath is £150 to £250 per m² and only makes sense when the floor is being replaced anyway.
Is floor insulation cheaper than loft insulation?
No. A loft top-up costs £400 to £900 for a whole house because the loft is empty and accessible. A floor needs boards lifted or a crawl space entered, so a whole ground floor is £3,000 to £7,000. Do the loft first if it is not already done.
Do I pay VAT on floor insulation?
No. Floor insulation is an energy-saving material under HMRC VAT Notice 708/6, so the installation is 0% VAT until 31 March 2027, after which the rate is due to become 5%.
Can I insulate a floor myself to save money?
Suspended floors from below are a realistic DIY job if you have the access and can fit a breather membrane correctly. From above, lifting and relaying boards without damage is the skilled part. Solid floors are a building job. Poorly fitted floor insulation that blocks ventilation causes rot, so if in doubt get a survey.
Is there a grant for floor insulation?
Not for most homeowners. Councils fund insulation for low income households through the Warm Homes: Local Grant until March 2028, and the council chooses the installer. For everyone else the 0% VAT rate is the support. Our insulation grants guide has the detail.