Everything UK homeowners need to know about loft insulation in 2026. Types compared, costs explained, grant eligibility checked — independent and unbiased.
Key fact: A significant amount of heat — often around a quarter — can escape through the roof if your insulation isn’t up to modern standards. Heat naturally rises, so without effective insulation in place, it escapes through your roof — increasing energy bills and reducing comfort in your home.
Up to 25% of a home’s heat escapes through the roof. For the millions of UK homes with no insulation or insulation below the current 270mm recommended depth, this represents hundreds of pounds per year literally heating the sky. Loft insulation is the single most cost-effective home improvement for most UK homeowners — with payback periods of just 1–4 years and product lifespans of 40+ years.
The economics are compelling at any energy price point. But at current UK energy prices, a standard semi-detached loft insulation upgrade typically delivers savings of £150–£250 per year from day one. Over the 40-year lifespan of the product, that represents £6,000–£10,000 in cumulative savings — against an upfront cost of £300–£600.
Quick check: Look into your loft. If you can clearly see the top of the joists, your insulation is below 100mm — significantly underperforming. Current recommendation is 270mm. A top-up is inexpensive and immediately effective.
Scored across 5 factors: cost, efficiency, lifespan, risk level, and installation complexity
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Check My Home in 30 Seconds →| Type | Cost (semi-detached) | Annual Saving | Payback Period | Lifespan | Score |
|---|---|---|---|---|---|
| Foil Insulation Recommended | £200–£600 | £150–£250 | 1–3 years | 25–40 years | application-dependent |
| Fibreglass (Mineral Wool) | £300–£500 | £100–£200 | 2–4 years | 40+ years | 7.5/10 |
| Loose Fill | £350–£600 | £100–£180 | 2–5 years | 20–30 years | 6.8/10 |
| Rigid Board (PIR) | £600–£1,200 | £120–£220 | 3–6 years | 30–40 years | 7.0/10 |
| Spray Foam ⚠ | £1,000–£2,500 | £100–£200 | 8–15 years | 20–30 years | 4.0/10 |
Spray foam warning: Multiple major UK lenders decline mortgages on homes with spray foam on roof timbers. Removal costs £2,500–£10,000. See our full risks guide before making any decisions.
Suitability depends on your property’s construction and application t radiant heat back into the property. Particularly effective in draughty lofts, installs quickly, and carries generally lender-accepted when correctly installed and documented. For most UK homes, this is our first recommendation.
The most widely installed loft insulation in the UK (7.5/10). Laid between and over joists to 270mm depth. Excellent 40+ year lifespan and widely available from local installers. Ideal for straightforward, dry lofts with good access.
Never install spray foam on roof timbers without independent specialist advice. The mortgage and resale risks are well-documented and serious. Our scoring system rates it 4.0/10 for this reason alone.
Some UK homeowners qualify for fully or partially funded loft insulation through government schemes:
Our installer partners check your eligibility for all available funding as part of the free survey — at no cost or obligation.
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Check My Home Now →Cost data: Energy Saving Trust benchmarks (August 2026) and UK installer quotes. Grants: GOV.UK and official scheme operators. Savings: Ofgem Q3 2026 price cap £1,862/year. All figures indicative. Last reviewed: August 2026. View scoring methodology →
Cost data: Energy Saving Trust benchmarks (August 2026) and UK installer quotes. Grants: GOV.UK and official scheme operators. Savings: Ofgem Q3 2026 price cap £1,862/year. All figures indicative. Last reviewed: August 2026. View scoring methodology →