35mm Multiwall Polycarbonate

A clear 35mm sheet passes about 63% of daylight, roughly two thirds of what falls on it, and about the same as 32mm. The seven-wall structure that gives 35mm its insulation also scatters some light, so the room feels bright but soft rather than glassy. Choose bronze, opal or heat guard instead if glare or summer heat is the concern.

Yes. 35mm is the thickest multiwall sheet we stock and the current standard for new conservatory roofs. It loses about a sixth less heat than 25mm, and only a little less than 32mm. It comes in clear, bronze, white opal, bronze/opal dual colour and opal heat guard, in sheets up to 2100mm by 7000mm, cut to size.

We recommend a maximum sheet width of 1000mm for 35mm multiwall without extra support. The manufacturer allows wider spans at light loads, but 1000mm is the safe figure for a DIY roof. That figure is about the sheet, not the rafters beneath it, so check your wind and snow exposure, or call the technical team before ordering.

Only slightly. 35mm loses a little less heat than 32mm, but the difference is small and you are unlikely to notice it in a heated room. Both are seven-wall box structures passing about 63% of light in clear, and both insulate better than 25mm. Choose 35mm for a new roof and 32mm to match panels in an existing roof.

The largest 35mm sheet is 2100mm wide by 7000mm long. We cut to your width and length from that, to a tolerance of plus or minus 5mm. Bear in mind the recommended maximum width of 1000mm without extra support. Cut sheets are bespoke and non-returnable, so measure carefully. We can pre-tape the ends on request.