Proper insulation is one of the best investments you can make to improve energy efficiency, lower heating bills, and increase comfort in your home. However, the total cost of insulating a property depends on several factors, including the type of insulation, the size of the home, and any additional preparation work required. This guide breaks down all aspects of home insulation cost in the UK for 2025.
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Average total cost to insulate a home in the UK
| Insulation type | Typical cost range (small house) | Typical cost range (large house) |
|---|---|---|
| Loft insulation | £300 – £700 | £500 – £1,200 |
| Cavity wall insulation | £400 – £800 | £800 – £1,500 |
| Solid wall insulation (internal) | £4,000 – £7,000 | £8,000 – £12,000 |
| Solid wall insulation (external) | £8,000 – £15,000 | £12,000 – £20,000+ |
| Floor insulation (suspended floors) | £1,000 – £2,500 | £2,500 – £4,500 |
| Roof insulation (pitched roof, internal) | £1,500 – £3,000 | £3,000 – £5,000 |
| Roof insulation (flat roof) | £2,000 – £4,000 | £4,000 – £7,000 |
| Draught proofing (whole house) | £200 – £400 | £400 – £700 |
Note: All prices are inclusive of materials, labour, and VAT (at 5% for energy-saving home improvements).
Cost breakdown by insulation type
Loft insulation
One of the quickest and cheapest ways to boost energy efficiency. Mineral wool rolls are the most affordable option.
- Materials only: £5–£15 per m²
- Installed price: £300–£700 for most homes
Cavity wall insulation
Suitable for homes built after the 1920s with empty wall cavities. Typically filled with foam, beads, or mineral wool.
- Materials and installation: £400–£1,500 depending on property size
- Energy savings: Up to £300 per year for detached homes
Solid wall insulation
Older homes with no cavity need solid wall insulation, which can be applied internally or externally.
- Internal insulation: £90–£120 per m²
- External insulation: £120–£180 per m²
- Grants: Some support is available under ECO4 for eligible households
Floor insulation
Mainly for older homes with suspended timber floors. Insulating ground floors helps prevent cold draughts.
- Labour intensive: Involves lifting floorboards and installing rigid boards or mineral wool
- Typical cost: £1,000–£4,500
Roof insulation
Important for homes where the roof itself (rather than the loft floor) needs insulating — particularly for conversions.
- Pitched roof (internal insulation): £1,500–£5,000
- Flat roof insulation: £2,000–£7,000
Draught proofing
Sealing gaps around doors, windows, floors, and chimneys can save up to £125 per year in heating costs.
- DIY draught proofing: £100–£300
- Professional whole-home draught proofing: £200–£700
Additional costs to consider
- Old insulation removal: £300–£800
- Loft boarding (if using loft for storage): £25–£50 per m²
- Ventilation upgrades (after insulation): £100–£400
- Energy performance certificate (EPC): £60–£120 (if needed for grants)
How government grants can reduce your home insulation costs
In the UK, homeowners may qualify for financial help through schemes such as:
- ECO4 scheme: Free or subsidised insulation for eligible low-income households
- Great British Insulation Scheme (new 2024/25): Support for middle-income households
- Local authority grants: Vary by council and location
Applying for grants can dramatically lower your insulation costs — in some cases, insulation could be installed at no cost at all.
Conclusion – Typical total project costs
- Basic insulation package (loft + cavity walls): £700 – £2,000
- Comprehensive home insulation (including floors and solid walls): £6,000 – £20,000+
While full home insulation can seem expensive initially, the long-term savings on energy bills — often £300–£600+ per year — mean most homeowners recover their investment within a few years.
Proper insulation also improves comfort, cuts carbon emissions, and can add value to your property.