PolyReflex BIG 8 mm (3-layer) Reflective Hive Insulation Roll 1.20 x 15 m (18 m²)

01 · NO AIR GAP, NO INSULATION

Low emissivity only works facing a void

This material insulates by reflecting: its emissivity is 0.05 and it reflects 95 % of radiation (ASTM C 1371). But a low-emissivity surface only reflects if there is air in front of it: in direct contact with metal or wood the heat passes by conduction and the aluminium stops doing anything.

So on a metal roof, what you want is an air gap between the sheet and the insulation. And that is why the thermal resistances the maker declares are for an assembly, not for the material: 1.52 m²·°C/W in a wall with two 2 cm cavities, 2.46 in a roof with two 4 cm ones. The 8 mm alone do not give that figure.

02 · HOW MANY HIVE COVERS

Around 68 to the roll

At the usual 500 × 430 mm and a simple layout — two pieces across the 1.20 m width, 34 rows along the 15 m — a roll gives about 68 pieces, with offcuts left over for nucs and divisions.

It goes directly over the frames, over the crown board or over the feeder, or fixed to the inner roof. Buying the roll and cutting it yourself usually comes out below the price of the ready-cut format.

03 · IT IS A VAPOUR BARRIER

Which means deciding where the damp goes

The material is declared a vapour and air barrier (EN 12086): laid over the frames, it closes the roof of the nest. In winter the colony produces water vapour, and if it has no way out it condenses and drips onto the cluster.

Bees take cold far better than damp, so with the top closed you must make sure the moisture leaves another way — an upper entrance, an open mesh floor — or lay the insulation over the crown board instead of over the frames. That is not a fault of the product: it is how it is fitted.

04 · WHAT IT WITHSTANDS

−20 to +100 °C, and it does not rot

It is faced with aluminium on both sides with anti-corrosion treatment, so it keeps its low emissivity over time — which is where insulations with aluminium on one face only fail.

It is rot-proof, anti-condensation and resistant to damp and fungal growth. For fire behaviour it is classed B-s2,d0 (EN 13501-1) and M1 (UNE 23727-90).

05 · BEFORE YOU BUY

It comes on a roll: you are buying material, not finished pieces. You have to cut it, and you have to decide where it gets its air gap.