Repair a Corrugated Plastic Roof

Corrugated plastic sheeting, extensively used on sheds and outbuildings, is available in clear or tinted form and is a safer alternative to glass. The most common type has a 75mm round profile and is easily cut using normal hand tools.  It is also very light and easy to handle, but for the same reason, has to be firmly secured to supporting rafters, otherwise it will blow away in the slightest gale.

When a sheet has become damaged it can be removed easily after unscrewing or pulling out its fixings, and then simply slid from the roof.  Place a wooden wedge beneath the overlapping sheet to lift it away from the supporting material.  If the sheet you removed is in a fair condition, you can use it to mark off the new sheet using a grease pencil. The new corrugated sheet can then be securely clamped into place between a couple of boards to support it and a saw can be used to cut along the line.

Once the new sheet has been cut to size, slide it into place and ensure that the overlaps on each side are equal.  Drill fixing holes into the top parts of the ridges and make sure that these are slightly larger than the fixings you will be using to allow for expansion.

Nail or screw the sheets into place using plastic caps, ideally to protect the sheeting, and seal all nail heads using mastic. The final step is to smooth down the flashing if the sheet comes up against a wall, working the filler material carefully into the profile.

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