Q.I am siding a building that was framed and roofed two years ago and is sheathed with 15?32-inch OSB. The building paper blew off one of the gable walls, and now the OSB has turned gray and some of the strands are lifting from the surface. Is the OSB still sound as structural sheathing? I cut out one of the window openings, and it looks like only the top surface - less than 1?32 inch - is affected; the rest of the panel is still tightly glued and has its original color (see photos, below).A.Bryan Readling, P.E., an engineered-wood specialist...

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