Description
Polycell ThermaWrap 4mm Insulation Foil is a reflective foil insulation built around a closed-cell XPE foam core, giving it genuine thermal performance rather than relying on foil alone. That foam core is faced with a bright aluminium foil surface on one side, reflecting radiant heat away from or back into a building depending on the season, and a low-emissivity antiglare backing on the other, which keeps installer glare down without compromising the reflective performance where it counts.
It’s built specifically for thermal control in commercial roofing, residential roofing and external wall construction, sitting within the building envelope to genuinely reduce heat transfer through the roof or wall assembly rather than just adding a vapour layer. The foil lamination is woven for tear resistance, so the roll handles the pulling and stapling of a real roofing or framing install without shredding at the edges the way an unreinforced foil product would.
ThermaWrap is available in three thicknesses — 4mm, 6.5mm and 8mm — all sharing the same closed-cell core and reflective foil construction, so a builder can step up the insulation performance for a colder climate or a more exposed wall without changing products. This 4mm roll is supplied as a 30m² pack, a practical size for sheeting a section of roof or wall without excessive off-cuts on a typical residential job.
Because the core is closed-cell rather than an open foam, it doesn’t absorb moisture the way some cheaper insulation backings can, which matters on a roofing job where the product may sit exposed to condensation before the roof covering goes on. Pairing the reflective foil face correctly — facing the air gap it’s meant to reflect across — is what actually delivers the thermal benefit, so installation orientation is worth getting right rather than treating the roll as symmetrical.
Technical Specifications
| Core | Closed-cell XPE foam |
|---|---|
| Surface | Bright aluminium foil, woven lamination |
| Backing | Low-emissivity antiglare |
| Thickness | 4mm (also available in 6.5mm, 8mm) |
| Pack size | 30m² roll |
Where to Use
- Commercial and residential roofing
- External wall construction
- Applications needing a reflective thermal barrier within the building envelope
How to Apply
- Plan the run — measure the roof or wall section against the 30m² roll to minimise off-cuts.
- Orient the foil face — position the bright aluminium surface toward the air gap it needs to reflect across.
- Fix in place — staple or fix along the framing, keeping the woven foil surface taut to avoid sagging.
- Overlap joins — lap adjoining rolls to maintain a continuous reflective barrier.
- Complete the build-up — proceed with roofing or cladding over the top once the foil is fixed.
Important Notes
- Orientation of the reflective foil face affects thermal performance — install with the foil facing the air gap.
- Keep the roll dry prior to installation to protect the foil surface.
- Also available in 6.5mm and 8mm thicknesses for higher-performance applications.
