I have a large, low slope, shed style roof over my garage that has been leaking for about a year now. The roofing on there now is gravel over something with lots of moss growing everywhere. I don’t have the money to replace the roofing with something expensive, so I’m wondering if I can repair it or can you suggest a cheap alternative?

From your description your roofing is probably old tar and gravel roofing. When this type of roofing has moss on it and it is leaking, you can remove the moss and patch the leaks (if you can find them). But you may be throwing good money after bad when you consider your time to remove moss, find the leaks and purchase and install the tar. This roof is probably at the end of its life expectancy, which means you’ll be patching and repairing from now until you finally get frustrated and replace the roofing.

In my opinion, the best replacement product for a low pitch roof is a material called “torch-on” or “torch-down” two-ply membrane. Unfortunately, it is expensive (about $6.00 per square foot) and requires a professional roofer for a guaranteed, quality installation. However, for garages, patios, carports, outbuildings and habitable areas if you cannot afford “torch-on” roofing, you may consider a new, less expensive alternative called HR Cap Sheet. This is a one-ply “peel & stick”, self-adhesive, elastomeric product that can be installed by a skilled homeowner on roofs with slopes greater than 1 in 12. You will have to strip the old roofing off and prepare the bare roof deck as directed. The product comes in a variety of colours, and it has a 15 year warranty against manufacturer’s defects. So, be sure to follow all the manufacturer’s installation instructions or hire a qualified roofing contractor to help you with the installation. Most building supply stores carry this product or an equivalent material.

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This article was written by Steven Cannon, a Registered Building Official and partner in Lynch Building Inspection Services Ltd. of Nelson, British Columbia. It originally appeared in The Nelson Express.

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