Metal roof on uneven strapping / purlins
My simple gable roof is built with trusses covered by OSB then underlayment then 2×4 strapping/purlins. The top chords of some of the trusses seem to be slightly bowed, because if I lay a straightedge from peak to eave, along some of those lines one or more of the purlins is up to 1/2″ higher than the others. The roof has a 4:12 pitch and covers a 20′ width and 48′ length.
To install Classic Rib exposed-fastener panels, how much variation in the purlin height is tolerable?
If I need to shave off the high areas on some purlins, would an electric planer be the best tool? (I screwed the purlins down, so I can remove the screws before planing.)
GBA Detail Library
A collection of one thousand construction details organized by climate and house part