Tim Hance discovered deteriorated OSB eave (soffit) sheathing at a recent inspection in Friday Harbor on San Juan Island. In this case, the lack of a metal drip-edge flashing detail at the edge of OSB sheathing (under the gutter) appears to be the contributing factor. Amazingly, installing such a drip-edge flashing detail isn’t required. If you intend to re-roof your home, I recommend having the roofing contractor install drip edge flashing everywhere, e.g., at all edges of the roof. This will help prevent potential water damage. Here, this owner will need to replace a fairly significant amount of sheathing, together with some roof work, which might prove expensive.