Fiberglass roofing sheets vary in thickness and are available in a variety of colors. The panels are durable and will not rust like metal roofs do. When used as a patio covers, sheets blocking UV rays while the light in, and fiberglass stands up better to hail than any other roofing, especially acrylic or glass fiber. Usually plastic roofing sheets are corrugated, although some manufacturers offer other structures which are largely used in greenhouse construction.
Pre-drill holes on every fourth increase of the corrugation on both upper and lower edges of the plastic roof panels. Fiberglass roofing sheets expands and contracts with heat, so use a drill bit slightly larger than the circumference of the fastener. Drill holes 1 inch from the end of the sheet. Screw the first panel in place. If you drive with plenty of caulk along the side of the first part of the plastic and along the side of the next piece of plastic. Overlap the edges and secure the second panel in place. The seal forms a weather seal.
Continue caulking and screw the plastic film until the roof is covered. If cutting the plastic is needed, use a jigsaw with a fine-toothed blade. Add flash if the fiberglass roofing sheets adjoins another part of the roof with a different finish. Flashing covers the seam between the two surfaces and prevents the water from flowing down the walls or accumulate on the roof. Use tin snips to cut a length of flashing size. Apply roofing glue on the bottom and press it into place.