I have written about oriented strand board (OSB) a number of times before. The topic most often comes up when talking about L-P innerseal siding. However, OSB is available in sheets as well and is used for other applications such as sheathing that is covered by other material.
This photo below is one of the most unsuitable applications I have seen forOSB. The key to longevity, for this product, is keeping it dry. It is a shredded/chopped/glued back together wood product and, when moisture can get into the edges, ends, soak down into the top, it does not weather a whole lot better than a cardboard box. Now, in theory, the OSB sidings are made to be more durable -- if they are installed exactly right and kept painted, caulked and maintained.
The photos below show exposed trim that is cut from OSB. It was buckled, warped and de-laminating/decaying in a number of different locations. In some places they had tacked a metal flashing over it, to protect it but this was not working well at all. The second photo is closeup, so you can have a good gander at it.
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Bellingham WA home inspections
Steven L. Smith