Energy and green upgrades
Loft insulation: cost, ECO4 and GBIS grants (2026)
Loft insulation slows heat escaping through your roof and is one of the cheapest energy upgrades. Eligible households may get it funded through ECO4 or the Great British Insulation Scheme. The Energy Saving Trust recommends a depth of 270mm of mineral wool. Get a quote, or check grant eligibility first.
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Get matchedWhat it is
Loft insulation is a layer of material, usually mineral wool, laid across the floor of an unused loft to slow the heat rising out of your home. Around a quarter of heat can be lost through an uninsulated roof, so it is often the first upgrade to make.
It is inexpensive, quick and, for eligible households, frequently fully funded by a government scheme.
How it works
For a standard accessible loft, insulation is rolled out between and over the ceiling joists to the recommended depth. The Energy Saving Trust recommends 270mm of mineral wool.
Where the loft is used for storage, boarding can be raised on battens so insulation depth is not squashed. Rooms in the roof, or hard-to-treat lofts, need a specialist approach.
A straightforward loft is often done in a few hours.
Cost
- Standard loft (DIY or installed)
- Get a quote Among the cheapest measures; cost depends on loft size and access.
- If grant-funded
- Potentially fully funded ECO4 or GBIS may cover the cost for eligible households (Ofgem).
- Recommended depth
- 270mm mineral wool Energy Saving Trust recommendation.
Who it is for
- Almost every home with an accessible, uninsulated or under-insulated loft, since it is cheap and effective.
- Lower-income and benefit-eligible households, who may get it funded through ECO4 or GBIS.
- Homeowners planning a heat pump, since good insulation helps it run efficiently.
Grants and savings
- ECO4: means-tested funding for insulation in eligible homes, delivered by obligated suppliers (Ofgem).
- Great British Insulation Scheme: further means-tested help with insulation (Ofgem).
- Loft insulation reduces heat loss through the roof, lowering heating bills; the Energy Saving Trust recommends 270mm of mineral wool.
How to choose a vetted installer
- For grant-funded work, the installer must be TrustMark-registered and the measure delivered under the scheme rules.
- Check the loft is dry and well-ventilated first; insulating a damp loft without addressing ventilation can cause condensation.
- Get the recommended depth confirmed and, for grant work, a written statement of what is covered.
Frequently asked questions
Can I get loft insulation for free?
Eligible lower-income or benefit-receiving households may get loft insulation fully funded through ECO4 or the Great British Insulation Scheme, delivered by a TrustMark-registered installer. Eligibility is means-tested, so check the criteria on Ofgem before assuming you qualify.
How deep should loft insulation be?
The Energy Saving Trust recommends a depth of 270mm of mineral wool for a standard loft. Existing insulation that is thinner or compressed can be topped up. If you board the loft for storage, raise the boards so the insulation is not squashed.
Does loft insulation help with a heat pump?
Yes. Reducing heat loss means a heat pump can keep your home warm at a lower flow temperature, which makes it more efficient and cheaper to run. Good loft insulation is one of the simplest ways to prepare a home for a heat pump.
Sources
Editor, Sorted Property
Oliver leads Sorted Property's editorial coverage of UK home services. He researches and writes the plain-English guides that help homeowners choose between installers and trades, drawing on the standards set by bodies such as MCS, TrustMark, the Energy Saving Trust and the Property Care Association, and is clear about what to check before any work starts.
Last reviewed: 11 June 2026