Short answer
A multifoil roll is typically 1.2–1.5m wide by 10m, covering 12–15m² before overlaps; bubble foil rolls are longer and thinner. Add 10–15% for laps and buy the manufacturer's tape.
- Multifoil rolls: 12–15m²
- Bubble rolls: 30–75m²
- Allow 10–15% for overlaps
- Manufacturer's tape only
Roll types and what they cover
| Type | Common roll sizes | Thickness | Coverage per roll | Indicative price | Use |
|---|---|---|---|---|---|
| Bubble foil (single or double) | 1.2m × 25m; 1.5m × 50m | 3 – 8mm | 30 – 75m² | £40 – £200 per roll | Sheds, garages, radiators |
| Foam foil | 1.2m × 25m | 5 – 10mm | 30m² | £60 – £150 per roll | Garage doors, floors |
| Multifoil quilt | 1.2m × 10m; 1.5m × 10m | 30 – 45mm | 12 – 15m² | £150 – £400 per roll | Rafters, loft rooms, walls, floors |
| Reflective VCL | 1.5m × 50m | <1mm | 75m² | £90 – £250 per roll | Warm side of roof and wall build-ups |
Retail ranges, material only, compiled and reviewed 3 September 2026.
How many rolls
Measure the area to be covered, add 10–15% for overlaps (multifoil joints overlap 50–100mm) and waste, and divide by the roll coverage. A typical semi-detached roof slope pair is 55–75m², so five or six 1.5m × 10m multifoil rolls. Tapes are sold separately: allow one 50m roll of manufacturer tape per two rolls of quilt.
Fitting basics
- Reflective face towards the air gap. Multifoil: both faces, both gaps.
- Run rolls across rafters where possible, tensioned, stapled every 100–150mm.
- Overlap and tape every joint with the product's own tape; generic aluminium tape fails.
- Counter-batten over the quilt to form the internal gap before plasterboard.
- Keep the eaves and ridge ventilation open.
DIY or installer
Outbuildings, garages and floors are reasonable DIY jobs. A roof slope or loft room often involves controlled work with a target U-value; get it surveyed and specified. Building regulations.
A free survey tells you the build-up and the quantities, or quotes the whole job.
Questions homeowners ask
How much foil insulation do I need for a loft?
Can I fit a foil roll myself?
Which tape should I use?
- SuperFOIL — product range — checked 2 September 2026
- Energy Saving Trust — Roof and loft insulation — checked 2 September 2026