corrugated plastic roofing – panels and sheets

Corrugated plastic roofingThe roofs of many home extensions designed as sun rooms and conservatories, but not intended as habitable rooms, are covered with corrugated plastic roofing panels or sheets. Corrugated plastic is a long-lasting material, but leaks can develop. Physical damage to the plastic can be caused by heavy objects being thrown or blown on the roof during a gale. A heavy fall of snow cascading from the main roof could also cause cracks lf this occurs, take off the damaged sheet and replace it with a new one. Take a little of the old sheet with you when you go shopping to make sure the profiles match exactly. When fitting the new panels and sheets, remember that each should overlap its neighbor by two corrugations, and that overlaps between the ends of sheets should be at least 150 mm. Sealing washers may be defective. The sheets are fixed to wooden rafters with screws or nails, or to iron rafters with clips. Such fixtures should have a nail cap and a rubber or plastic washer between the head of each nail and the sheet, to stop the rain getting through. These may have deteriorated, or might never have been fixed in the first place. Replace any defective washers; install them where they are missing. You can buy replacement caps and washers, as well as nails if these need renewing. The flashing may have come adrift from the wall, or be defective. You may be able to re-fix loose flashing back in the mortar joint as described in this chapter. If the flashing is defective, buy and fit a replacement. Flashing specifically for corrugated plastic roofing materials is available.  Support for the sheets may be insufficient, in which case they can buckle, causing gaps through which rainwater can penetrate. The only remedy is to provide extra support, and replace the affected sheets.

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