How to Install Corrugated Plastic Roofing
Corrugated plastic roofing is a long-lasting and low maintenance alternative to a corrugated metal roof. Plastic is much lighter and easier to work with, making it popular with home owners wanting to save money that could be spent hiring professional installation teams. In order to install your plastic roof correctly and prevent leaks, you should follow the instructions below carefully.
Step 1 – Prepare Roof
The roof should have a pitch of at least one inch per foot to allow water to drain properly. If your roof has a shallower pitch, you may need to use additional weatherproofing measures. For a secure and attractive finish, you should use molding strips on top of the rafters. Use the rounded molding strips on the vertical rafters and the corrugated ones on the horizontal cross-braces. Attach the moldings using galvanized nails to prevent rusting in case of any leaks. This can be a time-consuming process that is significantly quicker if you use a nail gun.
Step 2 – Cut Roofing to Size
Although plastic roofing is very strong, it is also easy to cut it to your required size. Some types of plastic can be cut using garden shears or scissors, but for others, you may need to use a fine-toothed saw. Higher quality plastics will be easier to cut and leave a cleaner line.
Step 3 – Pre-drill Holes
The installation of the roofing is much easier if you drill the holes for the fasteners in advance. Ideally, you should aim to have the fasteners at the high point of every fourth corrugation. The pre-drilled holes should be between eight and ten millimeters in diameter and two millimeters wider than the fasteners you are using to allow space for expansion when the roof is exposed to heat. It is easier to drill the holes if you use a stick with a hole drilled in it as a guide and to drill from what will be the underneath of the roof.
Step 4 – Fastening
Use special roofing fasteners rather than standard screws to secure the corrugated sheets as they have a waterproof seal underneath the head that prevents leaks. When joining panels, you should use silicone sealant along their vertical length and overlap the sheets by one corrugation. Be sure to use a generous amount of sealant so that there are no gaps and to receive the best performance. Take care to position your ladder securely and not to over-stretch when fastening the corrugated sheets. Ideally, you should have a friend assist you by holding your ladder steady.
Step 5 – Finishing
For an attractive finish and additional weather protection, especially if your plastic roofing adjoins another building, you can use flashing to improve the seal. If you live in an area with a high level of rainfall, it may also be wise to invest in guttering that can be installed after the plastic roof is in place.
(For an unconventional—but environmental—approach to roofing check out "Green Roofs: Gardens in the Sky".)