Two months ago I purchased an old house in Fauquier that had been moved up to higher ground when BC hydro flooded the farmland to create Arrow Lake. Anyway, the guy I bought the house from showed me receipts for the asphalt shingle roof and new insulation he installed six years ago. The thing I can’t understand is why the shingles are starting to curl up already. They look like they’re 15 years old, but I saw the receipts. Do you have any ideas on this?

We often see this type of problem with roofing that was recently installed and too worn for its age. It is unfortunate because you are not getting the type of life expectancy out of the shingles that the manufacturer predicts and you should expect. The most common causes for rapid shingle deterioration are a lack of roof venting and poorly installed insulation.

For instance, you mentioned that the previous owner had re-insulated the old attic space when he installed new shingles. One of the most common mistakes when re-insulating is to carelessly fill the horizontal ceiling structure. It is fine to add six, twelve or even fifteen inches of additional insulation to an attic that had little or none. However, care must be taken to ensure that the old and new insulation does not come in contact with the underside of the roof deck at the outside walls.

This insulation / roof deck contact surface will transfer heat from your house directly to the asphalt shingles causing them to expand and contract (“cycle”) significantly more than they were designed to withstand. As well, the insulation is blocking the incoming air flow through the soffits into the attic. This creates a hot and possibly humid attic space which leads to mould, mildew and another reason for a decrease in shingle life expectancy.

Fortunately, your shingles are still new enough to warrant saving. Here’s what you can do. Measure the distance between your rafters. Then purchase from your local building supply store one appropriately sized cardboard or styro-foam insulation baffle for each space between your rafters. (I prefer the cardboard baffles because they hold the insulation further away from the underside of the roof deck). Then, you may need to drill holes in your soffits and install soffit vent grills if your soffits have no vents. This will let air into the attic through the newly installed baffles. Also, install large gable end vents or some form of “top of roof” venting such as turbines, passive air vents or continuous ridge venting to provide the incoming soffit air with an exit at the top of the roof.            

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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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