Ask the Architect

More on roofs

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Q. We’re perplexed by what to do about our roof after reading your column last week. We’re going to put solar panels on our house. Our roof is about 10 years old. The first question is, do we put a new roof on before the solar panels? The solar company said it’s a good idea, although they told me solar panels shade the roof from damage by sunlight and the roof “could” last a lot longer. Is this true? Also, we understand, from researching, that the solar panels will outlast any shingle roof. So even if we change the roof, we’ll possibly have to remove the panels to replace the roof in the future. Does that seem like a reasonable idea and is there a better alternative?

A. I know that the solar companies generally dismiss this as “no problem,” and I’ve heard the comments about the panels protecting the roof, but I’ve also seen leaking from brackets in a few cases, though it’s not as common anymore, with the extra membrane layers installed around the bracket feet that attach to the roof. The fact is that asphalt shingles aren’t really a long-term solution based on what they’re made of.

Materials break down over time. Asphalt shingles are granular-coated over layers of different tar-like or fibrous compounds that dry out and break down due to exposure to air, water and sunlight. It can be a long time before the shingles need replacing, and it’s best to replace the roofing before installing the shingles, but I’ve never seen a roof last as long as the manufacturer says it will for the reasons outlined in my last column: heat buildup, sunlight, rain erosion, etc. For those reasons, I installed a steel roof with standing seams (or fins) for side attachment on the raised fins so there will be no roof penetration by the roof racks that hold the panels. The salespeople usually look at it with surprise, because they’re used to the asphalt shingle approach. I haven’t selected panels yet because I want a system that will power on when the gas company cuts service to everyone’s generators. Metal roofs are the only system I can endorse, because I know that asphalt shingles won’t last as long.

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