Multifoil insulation explained: is SuperFOIL right for your home?

If you've been researching loft or roof insulation, you'll have come across multifoil insulation — and brands like SuperFOIL. It looks nothing like the fluffy rolls most people picture, and that puts a lot of homeowners off. So what is it, and is it right for your home? Here's the plain-English version.

What is multifoil insulation?

Multifoil is a thin, multi-layered product made of reflective foil sheets sandwiched with insulating wadding or foam. Instead of relying purely on thickness to slow heat loss, it reflects radiant heat back into your home. Because it's slim — often just 30–40mm — it's popular where there simply isn't room for thick rolls or boards.

SuperFOIL is one of the best-known multifoil brands in the UK, with products designed for lofts, roofs, walls and floors. Like other multifoils, its strength is performance-per-millimetre rather than raw bulk.

Where multifoil works best

• Loft conversions and warm roofs — fitted between and under the rafters, it insulates the sloped ceiling without eating into headroom.
• Tight spaces — where a 270mm roll of mineral wool simply won't fit.
• Alongside other materials — multifoil is often combined with PIR boards or mineral wool to hit the required performance in a slim build-up.

Multifoil vs mineral wool vs PIR

There's no single winner — it depends on the job. Mineral wool is the cheapest way to insulate an open loft floor. PIR boards give the highest performance per millimetre for boarded floors and conversions. Multifoil and SuperFOIL sit between the two: slim, reflective, and excellent where space and headroom are at a premium. A good installer will often use them in combination.

The catch: it has to be fitted correctly

Multifoil only performs as promised when it's installed with the right air gaps on either side and properly sealed at the joints. This is exactly why the installer matters as much as the material. A poorly fitted multifoil can underperform — so it's worth using vetted, accredited insulation installers who know how to detail it correctly.

The bottom line

If you've got headroom to spare, traditional rolls or boards are usually the cheaper route. But for loft conversions, awkward roof spaces and slimline upgrades, multifoil and SuperFOIL insulation can be the ideal solution — provided it's fitted right. Not sure which suits your home? Tell us about your project and we'll advise, then match you with installers so you can compare quotes.