Underfloor Insulation Cost in the UK: Prices, Savings, and Options
Underfloor insulation costs £500 to £2,500 professionally installed and saves up to £115 per year on gas heating for a detached house. Floors account for around 10 to 15% of heat loss in an uninsulated home, making floor insulation a worthwhile upgrade after loft and wall insulation. The cost and approach depend entirely on your floor type: suspended timber or solid concrete. This guide covers both, with exact costs, DIY options, and when the ECO4 scheme can fund the work for free.
Cost by floor type and property
| Floor type | Method | Cost (3-bed semi) | Annual saving | Payback |
|---|---|---|---|---|
| Suspended timber (from below) | Rigid boards or mineral wool between joists | £500 to £1,000 | £70 | 7 to 14 years |
| Suspended timber (from above) | Lift boards, insulate, relay | £800 to £1,500 | £70 | 11 to 21 years |
| Suspended timber (DIY from below) | Rigid boards pushed up between joists | £150 to £400 | £70 | 2 to 6 years |
| Solid concrete (insulation on top) | Rigid foam plus new floor finish | £1,500 to £2,500 | £55 | 27 to 45 years |
Source: Energy Saving Trust. Savings for a 3-bed semi on gas at Ofgem Q1 2026 rates. Professional costs include materials and labour.
The financial case is strongest for suspended timber floors insulated DIY from below, and weakest for solid floors (where the payback exceeds the material lifespan). Solid floor insulation makes most sense when you are already replacing the floor covering for other reasons.
Use our insulation savings calculator for your specific property type.
Savings by property type
| Property type | Annual saving (suspended timber) | Annual saving (solid concrete) |
|---|---|---|
| Detached house | £115 | £85 |
| Bungalow | £95 | £70 |
| Semi-detached | £70 | £55 |
| Terrace | £50 | £40 |
Source: Energy Saving Trust. Gas heating at Ofgem Q1 2026 rates. Detached homes save more due to larger floor area.
What type of floor do you have?
Suspended timber floor: Common in homes built before 1950. The floor sits on timber joists with an air gap underneath. You can usually identify it by the slight bounce when you walk, visible air bricks in the external wall near ground level, and floorboards visible at the edges of rooms. If you have a cellar or crawl space, you can see the underside of the floor.
Solid concrete floor: Standard in homes built after 1950. The floor is a concrete slab sitting directly on the ground. It feels rigid with no give. There are no air bricks at ground level on the relevant walls. If your home was built after 1990, the concrete floor is likely already insulated.
If you are unsure, check your EPC certificate, which states the floor type and insulation status. Use our EPC improvement planner to see how floor insulation would affect your rating.
Insulating a suspended timber floor
From below (best approach if accessible)
If you have a cellar or a tall enough crawl space (600mm minimum) beneath the floor, insulating from below is the least disruptive method. Rigid insulation boards (PIR or EPS) are cut to fit between the joists and held in place with friction, battens, or netting. The insulation sits against the underside of the floorboards with a small air gap below for ventilation.
This approach costs £150 to £400 in materials for a DIY job, or £500 to £1,000 professionally. The work takes a day for a competent DIYer. Professional installation takes half a day.
See recommended rigid PIR insulation boards for the best products for underfloor use.
From above (when no access below)
If there is no access from below, the floorboards must be lifted, insulation fitted between the joists, and the boards relaid. This is more disruptive and expensive (£800 to £1,500 professionally) because it involves moving furniture, potentially relaying floor coverings, and careful handling of old floorboards that may crack during removal.
This approach is best combined with other floor work such as replacing damaged boards, sanding the floor, or fitting new carpets. Doing the insulation at the same time adds relatively little to the total disruption and cost.
Combine draught-proofing with floor insulation
If you are lifting floorboards to insulate, it is the perfect time to draught-proof the floor at the same time. Seal gaps between boards, around the edges, and along the skirting. This adds very little cost and addresses the other major source of floor-related heat loss.
Insulating a solid concrete floor
Solid floor insulation involves laying rigid foam insulation boards (typically 50 to 100mm PIR) on top of the existing concrete, then laying a new floor surface on top. This raises the floor level by 60 to 120mm, which affects door clearances, skirting boards, stair transitions, and kitchen units.
The cost (£1,500 to £2,500 for a 3-bed semi) reflects this complexity. The work is disruptive: the room must be completely emptied, the old floor covering removed, insulation laid with a damp-proof membrane underneath, and a new floor surface (screed, floating boards, or tiles) installed on top.
Solid floor insulation rarely makes financial sense as a standalone project because the payback is 27 to 45 years. It is best done when you are already renovating the ground floor, replacing the floor covering, or converting a ground floor room. The insulation adds £500 to £1,000 to a renovation that is happening anyway.
Underfloor ventilation: do not block it
Suspended timber floors rely on air circulation underneath to prevent moisture buildup and timber rot. Air bricks in the external wall allow air to flow through the void beneath the floor. Never block these air bricks when insulating. The insulation should sit between the joists, not across the bottom of the void.
If air bricks are blocked by soil, debris, or overgrown plants, clear them. Blocked air bricks cause more damage than missing insulation. See recommended replacement air brick covers if yours are damaged.
Check for asbestos in old floor tiles
Some vinyl floor tiles from the 1950s to 1980s contain asbestos, particularly the 9-inch square tiles common in that era. If you need to lift or disturb old floor tiles to insulate a solid floor, have them tested before proceeding. Do not sand, break, or scrape them. Your local council can advise on testing and safe removal.
Grants and funding
The ECO4 scheme funds underfloor insulation for eligible households as part of a whole-house retrofit. If you qualify for ECO4, the assessor will include floor insulation in your package if your property needs it. The scheme runs until December 2026. Check our grant eligibility checker.
Underfloor insulation also qualifies for 0% VAT until March 2027 when installed by a VAT-registered professional.
Where floor insulation fits in the priority order
Floor insulation delivers less savings per pound than loft insulation (£355/year, £300 to £600 cost) or cavity wall insulation (£395/year, £400 to £1,500 cost). The recommended upgrade sequence is loft first, then walls, then draught-proofing, then floors. Floor insulation is the finishing touch, not the starting point.
However, if your suspended timber floor is the main source of draughts and cold feet, addressing it earlier delivers an outsized comfort improvement even if the pure financial return is lower. Use a recommended thermal imaging camera to identify where your home loses the most heat.
See our full guide to improving your EPC rating for the complete priority list. Track your savings with recommended energy monitors.
Frequently asked questions
How much does underfloor insulation cost?
Suspended timber: £500 to £1,500 professional, £150 to £400 DIY. Solid concrete: £1,500 to £2,500. ECO4 may cover the full cost. Use our calculator for your property.
Is underfloor insulation worth it?
For suspended timber floors done DIY, yes (2 to 6 year payback). For solid floors as a standalone project, the payback is very long. Best combined with floor renovation. Do loft and walls first.
Can I insulate under my floor myself?
Yes, if you have access from below (cellar or crawl space). Push rigid boards between the joists. No specialist tools needed. See recommended rigid insulation boards.
What type of floor do I have?
Bouncy with air bricks outside: suspended timber (pre-1950). Rigid with no give: solid concrete (post-1950). Check your EPC for confirmation.
Does underfloor insulation cause damp?
Not if air bricks are kept clear (suspended) or a damp-proof membrane is used (solid). Never block underfloor ventilation.
Data sources
Savings from Energy Saving Trust. Prices from Ofgem Q1 2026 price cap. Building standards from BRE SAP methodology.