Polynium Bubble Sheet
Insulated Sheets
How a reflective barrier works
Polynium bubble sheet is a reflective foil bonded to an air bubble layer. It works mainly by reflecting radiant heat rather than by resisting conduction the way a thick fibre blanket does.
That distinction matters. Under a metal roof in the sun, a large part of the heat arriving at the ceiling is radiated from the hot underside of the sheet. A reflective surface facing that heat sends most of it back, and it does so in a layer a few millimetres thick.
Where it suits
It is thin, light and quick to fix, which makes it the practical choice where there is no room for a thick blanket and no appetite for rebuilding the roof. It is common as a retrofit on existing sheds, under new sheeting on ordinary industrial buildings, and anywhere the goal is to take the edge off summer heat at a modest cost.
It also acts as a vapour barrier and adds a little acoustic damping, though neither is the main reason to choose it.
The air gap is not optional
This is the detail that decides whether it works. A reflective foil needs an air gap facing the reflective side. Pressed hard against the underside of the sheet, the foil conducts heat straight through and the reflective property does almost nothing.
A product installed tight to the sheet with no gap will underperform badly, and the usual conclusion drawn on site is that the material does not work. The material works; the installation removed the mechanism.
What it will and will not do
It will noticeably reduce radiant heat gain through a roof in summer, for a small thickness and a low cost. It will not match a properly specified fibre blanket or a PUF panel for overall thermal resistance, and it is not the answer for a cold store or a temperature-controlled process.
Being honest about that at the specification stage avoids disappointment later. Where the requirement is real thermal performance, use a real thickness of insulation. Where it is summer heat relief on a shed, this is often the most cost-effective option available.
What to send us for a quote
The covered area, whether it is new work or a retrofit, and what you are trying to achieve. If the building is refrigerated or process-controlled, tell us, because a reflective barrier is probably not the right product on its own.
Frequently asked questions
Does bubble foil really work?
For radiant heat, yes, and well for its thickness, but only if it is installed with an air gap facing the reflective side. Fixed tight against the sheet it conducts straight through and does very little.
Is it as good as rockwool?
No, and it is not intended to be. It is thin, cheap and quick, and it targets radiant heat specifically. A thick fibre blanket gives far more overall thermal resistance.
Can it be installed on an existing roof?
Yes. It is one of the easiest retrofits available, which is much of its appeal.
Does it act as a vapour barrier?
The foil layer does resist vapour, which is useful, but joints and edges have to be sealed for that to count across the whole roof.
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