Polycarbonate Roofing Sheets Cut to Size

Clear roofing is one of the most common jobs we cut polycarbonate for. A pergola that needs light without rain, an awning over a back door, a carport with a strip of daylight down the middle, or a single cracked panel on a patio roof. This page explains where flat solid polycarbonate is the right sheet for the job, how to pick a thickness, how to fix it so it lasts, and where a profiled roofing product from a roofing supplier is the better buy.

We stock flat solid polycarbonate sheet in clear from 1 mm to 8 mm, plus opal and grey tint, with a UV resistant surface. We cut it to your sizes in our own workshop. We do not stock corrugated, Trimdek-profile, twinwall or multiwall polycarbonate. If you are re-sheeting a whole roof that already runs on a corrugated or trapezoidal profile, buy matching profiled sheet from a roofing supplier, because a flat sheet will not lap or seal against the ribs of the sheets beside it.

Flat solid sheet earns its place where the frame is flat and you want a clean, glass-like look: infill panels between pergola rafters, framed awning panels, low-pitch lean-tos, roof light panels set into a framed opening, and replacements for flat panels that have cracked or gone cloudy.

Thickness is mostly about how far the sheet spans between supports and how much wind and hail it has to take. As a working guide for framed panels supported on all edges:

• 3 mm suits small panels and light awnings with supports roughly every 600 mm.
• 4 to 5 mm suits typical pergola and patio infills with supports around 600 to 900 mm apart.
• 6 to 8 mm suits wider spans, exposed sites, and anywhere you expect hail or people leaning ladders against the edge.

Solid polycarbonate is tough, but a thin sheet over a long span will drum in the wind and sag under its own weight on a flat roof. If in doubt, add a purlin rather than jumping two thicknesses. We are happy to look at a sketch of your frame and suggest a thickness before you order.

Most failed polycarbonate roofs fail at the fixings, not in the sheet. Polycarbonate expands and contracts a lot more than timber or steel, roughly 3 mm per metre over a hot summer day. Allow for that movement and the sheet stays flat and sealed for years.

• Drill fixing holes oversize, about 3 mm wider than the screw shank, so the sheet can slide under the head.
• Use screws with sealing washers and snug them down only until the washer seals. Overtightening dimples the sheet and starts cracks.
• Leave a gap of about 3 mm per metre of sheet length at edges and joins, and cover joins with an H or capping section rather than butting sheets hard together.
• Keep fixings at least 20 mm from the sheet edge.
• Give a flat roof at least a slight fall, around 5 degrees, so water and leaves run off instead of ponding.

If you would rather not drill on site, we can pre-drill or rout fixing holes and slots to a drawing on our CNC router . Routed holes are cleaner than a hand drill and come out exactly where your frame needs them.

Our UV resistant sheet is protected on one face. That face is marked on the protective film, and it must face the sky. Fit it upside down and the unprotected face yellows and goes brittle within a few summers. Peel the film as soon as the sheet is fixed, because film left baking in the sun becomes very hard to remove.

Clear gives the most light and the best view of the sky, but it also lets through the most heat and glare. Opal diffuses the light, hides leaves and dirt on top, and keeps the area under it noticeably more comfortable. Grey tint cuts glare while keeping a view through. For an outdoor living area that faces north or west, opal or grey is usually the more comfortable choice. PETG and acrylic are sometimes asked about for roofing, but polycarbonate is the one to use overhead, because it is far more impact resistant.

Be honest with yourself about the roof. If it is a long-run roof on purlins with no framing between them, a profiled corrugated sheet will span further for the same weight and match the neighbouring sheets. If you want insulation, for example over a sunroom, twinwall or multiwall polycarbonate traps air and holds heat far better than solid sheet. Both are roofing supplier products. Flat solid sheet is the right call for framed panels, visible infills and repairs.

Plastic Online is the online ordering side of Holland Plastics, a working plastics fabrication shop. Your panels are cut on the same floor where we do CNC routing, laser cutting, vacuum forming and plastic welding, so pre-drilled holes, notches around posts and odd shapes are all routine. See our plastic fabrication service for larger projects.

We cut to ±0.1 mm, and if a dimension is critical we will confirm it with you at quote stage. Finished panels ship Australia-wide from whichever capital-city depot is closest to you, and there is no minimum order, so one replacement panel is as welcome as a full pergola. Start with our cut-to-size page.