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How to Attach Corrugated Fiberglass Roof Panels

Samantha Belyeu

Corrugated fiberglass panels are made of synthetically produced glass fibers, designed to provide a waterproof seal along with a tough, durable structure with a lifetime expectancy of 20 years. Fiberglass sheets are resistant to corrosion, chemicals, rust and mildew, and are also shatterproof (unlike glass greenhouses), and require minimal maintenance. Panels are typically 26 inches wide and up to 20 feet long, and are available in clear or white. Their light weight and ability to be nailed, drilled, sawed and punched without damaging the sheet as a whole makes them relatively easy to install.

  1. Build the greenhouse frame if it does not already exist. Remove any old paneling from existing frames along with the corresponding nails or screws, leaving just the smooth-faced frame.

  2. Install filler strips (pieces of wood shaped to fit the corrugation of the panels) under the roofing at the eaves to ensure a complete weather seal. Filler strips generally come with fasteners or screws, but if not, pre-drill screw holes and screw them onto the eaves.

  3. Lay a corrugated fiberglass panel against the rafter, and have a helper hold it in place. The grooves should direct water down from the top of the greenhouse roof. Pre-drill holes for the fiberglass panel nails and hammer the first full-width panel to the rafters. Use four nails across the panel where it rests on each rafter, making sure that the roofing is snug to the framing.

  4. Place the next panel so that it overlaps into the groove of its neighbor panel. Apply a beaded line of adhesive caulk on both the overlapping surfaces and press them securely together to form a seam. Nail the second panel using the same method as the first. Repeat the procedure to complete the installation of the remaining full-width panels. If you have more than 20 feet to cover from eaves to ridge, lay the upper panels so that they overlap the lower panels by 12 inches. Cut the panels as necessary, using a saw blade for fiberglass to avoid cracks and catching.

  5. Install ridge caps at the ridge and any hips -- or any areas where the panels join at different angles -- after all panels are installed. The ridge cap should overlap the panels by at least 1 inch and sections of the ridge should overlap each other by 6 inches. Nail the ridge caps into the top of the frame using the manufacturer's guideline pattern, but do not nail overlapping sections of ridge caps.