Is floor insulation worth it?

For suspended timber floors, yes. The cost is low (£500 to £800 professionally, under £300 DIY), the comfort improvement is immediate, and grants can cover it entirely. For solid concrete floors, only if you're already replacing the floor surface for another reason. The savings of £50 to £70 a year don't justify ripping up a good concrete floor just to insulate it.

Can I insulate my floor myself?

If you have a suspended timber floor with crawl space access (500mm or more of clearance), yes. You'll need mineral wool batts or rigid insulation boards, netting or clips to hold them in place, a dust mask, overalls and a head torch. Materials cost £150 to £300. The key rule is don't block the airbricks. Those ventilate the void and prevent timber rot.

Does floor insulation reduce draughts?

Significantly, especially on suspended timber floors where gaps between boards let cold air rise from the ventilated void below. Combining insulation with draught-proofing (filling gaps between boards and sealing the skirting line) makes the biggest difference. Some homeowners find the draught reduction matters more to comfort than the actual heat saving.

What thickness of floor insulation do I need?

For suspended timber floors, 100mm to 150mm of mineral wool or 75mm to 100mm of rigid PIR board (like Celotex) is standard. For solid concrete floors, 50mm to 100mm of rigid foam board. Thicker is better for thermal performance, but you're limited by the joist depth on suspended floors and the acceptable floor level rise on solid floors.

Will floor insulation affect my EPC rating?

Yes, but modestly. Floor insulation typically adds 2 to 5 SAP points to your EPC score. That's less than wall insulation (10 to 40 points) or loft insulation (5 to 15 points), but it can be enough to tip you into the next band if you're close to the boundary. Combined with other measures, it contributes to the overall package.

Floor Insulation UK 2026: Costs, Types and Grants

Two completely different jobs. That's what most floor insulation guides get wrong. They talk about "floor insulation" as if it's one thing, when in reality your floor type determines everything: the method, the cost, the disruption and whether you can do it yourself.

Suspended timber floor? Relatively cheap, often accessible from underneath, and a solid weekend project if you're handy. Solid concrete floor? Expensive, disruptive, and almost always a professional job. Before you do anything else, you need to know which one you're standing on.

What Type of Floor Do I Have?

This matters more than anything else in this guide.

Suspended timber floors sit above a void. Wooden joists span the gap between your walls, with floorboards laid across the top. There's an air gap underneath, usually 150mm to 500mm, ventilated by airbricks in the external walls. Most houses built before the 1950s have suspended timber ground floors. You can usually tell by looking for airbricks at the base of your external walls, or by feeling draughts coming up between the floorboards.

Knock on the floor. If it sounds hollow, it's suspended timber.

Solid concrete floors sit directly on the ground. A concrete slab, sometimes with a damp-proof membrane, sometimes without. Most houses built after the 1960s have solid concrete ground floors. They feel solid underfoot (no bounce, no flex) and there are no airbricks in the external walls at ground level.

Some houses have both. A Victorian terrace might have suspended timber in the front reception rooms and a solid concrete extension at the back. Check each room separately.

Your EPC certificate should describe your floor type under the floor section, but it's not always specific. The knock test and airbrick check are more reliable.

What Does It Cost?

The price gap between the two floor types is significant.

Floor Type	Method	Typical Cost	Annual Saving	DIY Possible?
Suspended timber (from below)	Mineral wool or rigid board between joists	£500 to £800	£40 to £65	Yes, if crawl space accessible
Suspended timber (from above)	Lift floorboards, insulate, relay	£800 to £1,200	£40 to £65	Possible but harder
Solid concrete (insulation on top)	Rigid foam board + new floor surface	£1,000 to £1,500 per room	£50 to £70	Difficult

Costs based on Energy Saving Trust data and current installer quotes. Savings assume gas heating at current Ofgem cap rates.

The savings are modest compared to wall or loft insulation. £40 to £70 a year won't set the world on fire. But floor insulation does something the numbers don't fully capture: it eliminates cold feet and draughts. If you've got a suspended timber floor with gaps between the boards, the comfort improvement is immediate and noticeable. The house feels warmer even before the thermostat reading changes.

Insulating Suspended Timber Floors

This is the easier job, and the approach depends on whether you can get underneath.

From Below (Crawl Space Access)

If there's enough space to crawl under the floor (and roughly 500mm of clearance is the minimum for comfortable working), insulation can be fitted from below without disturbing anything upstairs. This is the cheapest and least disruptive method.

Mineral wool batts or rigid insulation boards are cut to fit between the joists and held in place with netting, clips or battens. The insulation sits against the underside of the floorboards, with the void below remaining ventilated. Those airbricks must stay open. Blocking them causes damp and timber rot, which is far worse than a cold floor.

£500 to £800 for a professional installation. A competent DIYer with a dust mask, overalls and a head torch can do it for £150 to £300 in materials. Mineral wool batts (100mm to 150mm thick) from any builders' merchant will do the job. Rigid PIR boards (like Celotex or Kingspan) are easier to handle in a tight crawl space but cost more.

From Above (No Crawl Space)

If there's no access from below, the floorboards have to come up. This is more disruptive and more expensive, but the insulation itself is the same: mineral wool or rigid board fitted between the joists.

While the boards are up, it's worth draught-proofing the gaps between boards and at the skirting line. Flexible filler or foam strips between boards, and decorator's caulk where the boards meet the skirting, can make a noticeable difference to draughts even without adding insulation underneath.

£800 to £1,200 professionally, depending on the room size and whether the existing floorboards can be relaid or need replacing.

Insulating Solid Concrete Floors

This is the expensive, disruptive option, and it's only worth doing if you're already replacing the floor surface for another reason (renovation, damp-proofing, level changes).

The method is to lay rigid foam insulation boards (typically 50mm to 100mm of PIR or EPS) on top of the existing concrete, then lay a new floor surface on top. That raises the floor level by 70mm to 120mm, which means adjusting door heights, skirting boards, kitchen units, radiator pipes and anything else that meets the floor.

£1,000 to £1,500 per room, including materials and labour. If you're already renovating the ground floor, the marginal cost of adding insulation is much lower because the floor is being disturbed anyway.

Don't dig up a perfectly good concrete floor just to insulate it. The savings of £50 to £70 a year don't justify the disruption and cost. Wait until the floor needs replacing for another reason, then insulate at the same time.

Grants for Floor Insulation

ECO4 covers floor insulation as an eligible measure. If you're on qualifying benefits and your home has an EPC rating of D or below, your energy supplier could fund the work at no cost, per GOV.UK. Floor insulation is less commonly delivered under ECO4 than wall or loft insulation because the SAP point improvement is smaller, but it is available, particularly as part of a package of measures.

The Warm Homes Local Grant may also cover floor insulation depending on your council's priorities, per GOV.UK. Household income must be under £36,000 and your EPC must be D or below.

GBIS includes floor insulation for eligible properties in council tax bands A to D. If you're unsure whether your home qualifies, the Great British Insulation Scheme guidance explains which properties and measures are covered.

The National Insulation Association maintains a directory of certified floor insulation installers if you're paying privately and want to find a qualified contractor.

Use our eligibility checker to see which schemes cover floor insulation for your property.

DIY vs Professional

Floor insulation is one of the few energy upgrades where DIY is genuinely practical, but only for suspended timber floors with crawl space access.

DIY makes sense when:

You have a suspended timber floor with 500mm or more of crawl space
You're comfortable working in a confined, dirty space
You want to save £300 to £500 on labour
You're doing it as part of a broader renovation

Hire a professional when:

The crawl space is tight (under 500mm) or has standing water
You're insulating a solid concrete floor
The floor has asbestos-containing materials (common in 1950s to 1970s properties, particularly vinyl tiles and adhesives)
You want the work covered by a guarantee

If you go the DIY route, the key rules are: don't block the airbricks (ventilation prevents rot), wear a proper dust mask (the crawl space will be filthy), and leave a small gap between the insulation and the floorboards to allow moisture to escape upward. The Energy Saving Trust has a step-by-step guide for DIY floor insulation.

The Decision Tree

Here's how to decide what to do about your floor.

Suspended timber or solid concrete? Knock on it. Check for airbricks.
Suspended timber with crawl space access? Insulate from below. Cheapest, least disruptive. DIY if you're able.
Suspended timber, no crawl space? Insulate from above when you next lift the floorboards for any reason.
Solid concrete, planning a renovation? Add insulation when the floor is being replaced anyway.
Solid concrete, no renovation planned? Leave it. The cost and disruption don't justify the savings on their own.
On qualifying benefits? Check ECO4 eligibility first. Free is always better than cheap.

Floor insulation won't transform your energy bills the way wall insulation does. But if you've got a draughty suspended timber floor and you're already insulating your walls and loft, the floor is the final piece. Cold floors make a warm house feel cold. Fix the floor and the whole house feels different.

Open the eligibility checker. Two minutes. You'll see every grant that applies to your home, including floor insulation.