Supply: £4–£8/m² for 100–200mm rolls. Installed in a loft to 270mm: £18–£26/m² — £750–£900 for a typical semi (EST-anchored). The budget classic, priced honestly.
Rolls at the merchant: 100mm £4–£5/m², 170mm £5–£7, 200mm £6–£8. Professional install to the 270mm standard lands at £18–£26/m² including labour, clearing and eaves detailing — effectively the same job price as mineral wool, since labour dominates.
Performance is near-identical to mineral wool (λ 0.040–0.044 vs 0.038–0.044) at similar money; mineral wool handles slightly better and edges fire/sound. PIR beats both per-mm at 3× the price — for rafters and floors where depth is tight, not lofts. Full matrix: compare insulation types.
Entirely DIY-able: gloves, mask, long sleeves — modern rolls itch far less than the 90s stuff. Lay cross-layered to 270mm, keep eaves ventilation clear, use loft legs under boarding. £200–£350 materials for a typical semi.
Loft insulation (fibreglass or mineral wool — the surveyor specifies) is core to ECO4 and WH:LG: could be fully funded for some eligible households; eligibility does not guarantee installation or zero contribution.
AC-coupled (battery has its own inverter) is the retrofit default: no rewiring of your array, works with any brand or age of system, £3,500–£6,000 installed for 5–10kWh usable. DC-coupled only makes sense if your inverter is due replacement anyway — a hybrid inverter + battery swap can be cheaper combined.
Feed-in Tariff payments are unaffected by adding storage — generation payments continue and deemed export isn’t metered down. On SEG, a battery lets you shift export into peak-price windows instead.
Match usable capacity to your evening consumption and summer surplus — the sizing guide has the tables. Most 4kWp homes land at 5–8kWh usable.
£4–£8/m² supply-only depending on thickness; £18–£26/m² professionally installed to 270mm.
Near-identical performance and price — mineral wool edges fire and sound handling; either is right for lofts.
Modern rolls are low-itch and safe with basic PPE. It's not asbestos and never was.
Via ECO4 or WH:LG it could be fully funded for eligible households — the scheme surveyor specifies the material.
Facts checked 21 August 2026. We link to official sources and show when facts were last verified. If a scheme changes, we update the page.
Free, independent, 60 seconds. We compare every option, check Government scheme eligibility and match you with one trusted local installer if you want one.
Check My Home →