Guide: Repairing the cottage roof
Weather conditions can do a number on the cottage roof. Here's how to make it watertight
Roll roofing is a kissing cousin of the asphalt shingle. Both are fibrous membranes impregnated with bitumen and protected under a granular coating. Roll is solid, not tabbed, more flexible than shingle, and covers with fewer seams. Roll roofing has never been in the good-looks game. But then it doesn’t have to be. Its niche is low slopes. At the cottage, that usually means outbuildings and lean-to additions with short rafter spans that don’t need to shed snow load. Shingles don’t work on these flatter roofs, and looks don’t count where the birds have a better view than passersby.
Unlike shingles, roll roofing has to be carefully and completely sealed when it’s laid down. Each three-foot strip is sealed to the roof deck and to adjacent, overlapping strips. That part has gotten easier. In conventional applications, the adhesive is heated with tar pots and torches. This torch-down application may be safe in the hands of a pro, but weekenders will want to check their insurance for fire coverage in the event of a DIY mishap.
The DIY alternative is self-adhered roll roofing. No stink, no flame, no black footprints on the patio. There are one-ply and two-ply options. In either case, you have to start with a sound plywood deck. One-ply requires a special primer on the deck before you roll out the roofing. With two-ply, you nail the first layer to the deck then peel-and-stick the cap layer.
Bob Sims, customer service manager for Bakor, a “building envelope systems” company headquartered in Mississauga, Ont., says two-ply’s double coverage is a little more foolproof for DIYers. And it carries a 20-year warranty against 15 years for the one-ply. Foolproof? Sims knows at least one first-timer who installed the product upside down, and, like the shingle manufacturers, he stresses the importance of the instructions printed on the packaging. For example, unlike self-seal shingles, roll roofing doesn’t rely on the sun to seal the overlaps, but heat is nonetheless important to get the roofing to lie flat. Sims says 5°C is a minimum temperature for safe application, and 10°C would be better. Unrolling the material ahead of time allows it to “relax” in the sun.
This article was originally published on November 4, 2003