Mixing OSB and Plywood on same roof section

Dawn Hintz
Is it OK to mix OSB and Plywood deck boards on the same roof section? If so, isn't there the possibility of an issue due to OSB's tendency to swell due to humidity/moisture exposure, which could possibly cause a problem with uniformity if the OSB deck boards expand but the plywood doesn't? If it isn't OK to mix the two, could you please cite the information source (NRCA, SMACNA, etc.) along with a link to the actual information? Thank you.
David Stermer
Dawn, Thanks for the question. I do not know of a problem that using both would cause. However, from my experience, a fastener pulls out of OSB with about 1/2 the force as that same fastener pulling out of the same thickness of plywood. The result is that the panel fastener spacing for OSB is significantly closer than for plywood. If both OSB and plywood are used on a roof, I would recommend using the OBS spacing through out. Regards, David Stermer

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