Solar panel installation

Q. I’m planning to install solar panels this spring and need to confirm, do I have to do anything to the roof to get it ready? The salesperson told me they have waterproofing techniques that are pretty reliable, and that they’ve never had a leak, but I’m skeptical. What’s the right way to attach the panels to avoid leaking? Will my roof take the weight?

A. Roofs aren’t always strong, especially when they sag. Look at your roof. Is there a sag across the ridge or a wave effect in the middle areas? That charming-old-house look tells me why they don’t build houses like they used to. Years ago, without proper scrutiny, undersized rafters and ridges were used pretty universally. When rafters went in, they still had some moisture content, and more stiffness. Over the years, rafters dried out and hardened up, holding their sagging shape. The contractors were long gone, and many “engineers’” reports (not really prepared by licensed professionals) listed roofs as “normal aging” or “settling.”

Roofing companies, with a conscience, then tell the owner they shouldn’t add additional weight and suggest stripping shingles before putting new ones on to avoid blame for even greater sag. Under-structured roof rafters bow and sag each day with the sun’s heat, even in winter, and as they bellow out, they stretch the shingles, which, even with their flexibility, still manage to dry out, becoming brittle and cracking. Leaks form, and you need a new roof sooner than you’d thought. Some roof manufacturers will then use this under-structuring as a reason not to honor the warrantee. So the builder didn’t do you any favors with the way they skimped, not having the rafters properly calculated by a qualified professional or by saving money on the cheaper, smaller rafter size.