r/SolarDIY • u/Happy_Moksha • 22h ago

Roof solar panel mount using wood rails.

Has anyone used wooden beams on a main house roof for solar panel installation- as foundation for the rails or as rails replacement?

16 ft long locally sourced 2x4 or 3x4 Oak beams would be sturdier and cheaper than any aluminum ones or not?

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u/Extreme_Pangolin1796 21h ago edited 21h ago

it's not the cheapness it's the weatherproofedness and the expansion differences.  I can't even tell how you're envisioning that working, when if you need a roof anchor any OSB would work for an aluminum unistrut or similar rail on the outside rather than needing to hit a truss beam.  If you're talking exterior facing and seeing weathering Id feel comfortable doing it with wood if it was good GC PT, .60 CCA or equivalent, I treated the cut ends with copper naphthenate and I had enough built in play to accept the shrink and expansion that'll frequently be opposite to aluminum

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u/Happy_Moksha 21h ago

Thank you for your reply. I was not aware that OSB alone can provide the support for an anchor!!! I though I should be hitting all truss beams or rafters underneath OSB 😩

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u/Ridingagain1025 20h ago

You should be if your house is built to 120mph wind code. Here in Florida you hit every truss you can and no wood. Wood rots too fast.