10mm Twinwall Polycarbonate

We recommend a maximum sheet width of 700mm for 10mm twinwall without extra support. The manufacturer's tables allow wider spans at light loads, but 700mm is the safe figure for a DIY roof. Sheet width alone does not make a roof sound, so check your wind and snow exposure, or call the technical team before you order.

Yes. Fit 10mm twinwall at a pitch of at least 5 degrees, and 10 degrees or more works better for run-off. A steeper slope clears rainwater faster and gives dirt less chance to settle. The flutes, the hollow channels inside the sheet, must run down the slope so any condensation drains out at the bottom edge.

Clear 10mm twinwall passes about 79% of daylight, bronze about 35% and white opal about 30%. Clear suits growing spaces and anywhere you want maximum light. Bronze cuts glare and some solar heat. Opal spreads the light evenly and removes the hard shadows a clear sheet can cast, which many people prefer over a seating area.

One side only. The UV-protected face is marked by the printed protective film, and it must face the sun. Fitted the wrong way up, we have seen sheets yellow and crack within a couple of years. Fitted correctly, the sheet carries a ten-year warranty against loss of light transmission. Keep the film on until the sheet is in position.

10mm twinwall suits light-duty covers: a greenhouse, cold frame, shed roof, small porch or garden canopy. It is light to handle and economical, but it insulates less than 16mm, and we recommend sheets no wider than 700mm. For a lean-to you will use often, choose 16mm. For a conservatory you heat and sit in, go to 25mm or thicker.