Which insulation type is best for your home? We score all options on thermal performance, cost, durability, risk and suitability — completely independent.
How we score insulation types: Our independent ratings are based on thermal performance (20%), installed cost (15%), lifespan (15%), moisture & ventilation considerations (15%), ease of installation (10%), property suitability (10%), mortgage/resale considerations (10%) and sustainability (5%). No manufacturer or installer pays to influence these scores. Ratings are reviewed regularly — last reviewed August 2026.
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.
Every type scored across cost, efficiency, lifespan, risk, and installation complexity
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Check My Home in 30 Seconds →| Type | Score | Typical Cost | Annual Saving | Payback | Mortgage Risk |
|---|---|---|---|---|---|
| Foil Insulation Top Pick | application-dependent | £200–£600 | £150–£250 | 1–3 yrs | ✓ None |
| Fibreglass / Mineral Wool | 7.5/10 | £300–£500 | £100–£200 | 2–4 yrs | ✓ None |
| Underfloor Insulation | 7.2/10 | £400–£800 | £50–£100 | 5–8 yrs | ✓ None |
| External Wall Insulation | 7.0/10 | £6k–£15k | £200–£400 | 20–30 yrs | ✓ None |
| Internal Wall Insulation | 6.5/10 | £2k–£8k | £150–£300 | 10–20 yrs | ✓ None |
| Cavity Wall Insulation | 6.0/10 | £400–£800 | £150–£250 | 2–5 yrs | ✓ None |
| Spray Foam ⚠ | 4.0/10 | £1k–£2.5k | £100–£200 | 8–15 yrs | ✗ Major risk |
Spray foam warning: Multiple major UK mortgage lenders decline applications on homes with spray foam on roof timbers. See our full spray foam risks guide.
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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 →