Patterns asked: Pvc and polycarbonate sheet roofing come in a variety of profiles, sizes, and colours. Quality and prices vary immensely. The most common profile is corrugated. The most common lengths are 1800mm, 2400mm, 3000mm and 3600mm and less common, 4200mm, 4800mm, 5400mm and 6000mm. The cover width ranges from 610mm to 760mm and the colours include clear, opal, white, solar grey, blue, and green. Quality varies enormously from cheaper pvc sheets up to lifetime guaranteed polycarbonate sheets and the price varies accordingly. Guarantees range from zero to lifetime. Prices range from around $10 per sq metre to $36 per sq metre (not including screws or flashings). Sometimes the cheapest is not the most cost effective. Pamphlets relevant to the type of sheeting required are usually available from most stockists, it is advisable to read them.
Roof pitch Most type of PVC or polycarbonate manufacturers recommend a 10 degree pitch (approx 1 in 5.7 fall).A lesser pitch could require additional weatherproofing such as extra flashings or appropriate sealants.
Cutting Garden scissors or a fine tooth saw can be used to cut most sheets. The higher the quality, the easier the cutting. Sometimes a carborundum blade on a disk grinder will do the trick but only one sheet at a time or it could cause fusion and weld the sheets together.
Drilling Pre-drill the holes in the sheets before fixing. The holes should be 8mm to 10mm and at least 2mm larger than the shaft of the screws to allow for expansion and contraction. Ensure the holes are in the high part of the corrugation. Sometimes it might be easiest to lay the sheets upsidedown on the ground and pre-drill. Another tip is to use a stick with a hole in it as a guide for the drill.
Fixing Appropriate screws are readily available from any suppliers that stock the PVC or polycarbonate roof sheets. If the choice is available, hexagonal heads are the easiest to use. Most sheets should be fixed at every fourth corrugation and every second corrugation at gutters, ridging and overlaps.
Accessories Accessories such as ridge flashings, apron flashings and foam eave fillers are also readily available from any suppliers that stock the PVC or polycarbonate roof sheets.
Green roofing
