Mineral wool at joist level suits most lofts. Multifoil products such as SuperFOIL are useful where depth is limited or where the loft is being used as a warm, boarded space.
On this page
- Mineral wool
- SuperFOIL multifoil
- How to choose
- What we will tell you
Mineral wool
- Lowest cost per unit of thermal performance
- Laid at joist level, typically 300mm in two crossed layers
- Needs depth to perform — it cannot be compressed
- £10/m² at 100mm up to £30/m² at 300mm
SuperFOIL multifoil
- Thin build-up, useful where headroom or depth is restricted
- Often fitted at rafter level to create a warmer loft space
- Requires correct air gaps and detailing to perform as rated
- SF19+ £45/m², SF40 £65/m², with batten and board over foil at £55/m²
How to choose
If the loft is cold storage and there is room for depth, mineral wool is almost always the better value. If you are boarding out and want the space to feel usable, or the roof structure limits depth, a foil build-up at rafter level is worth considering.
What we will tell you
We do not upsell foil where mineral wool will do the job. If your loft is a straightforward storage space, we will say so.
Common questions
Is SuperFOIL better than mineral wool?
Not universally. Mineral wool gives better value where there is room for full depth; multifoil is useful where depth is restricted or the loft is being made into a warmer boarded space.
If you would like an honest opinion on your own loft, send us your postcode and a few photographs. Most lofts can be assessed and quoted remotely using satellite imagery, and we will tell you if work is not necessary.
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