Wood structural panels when designed to be permanently exposed in outdoor applications shall be of an exterior exposure durability.
Roof sheathing exposure.
It s also suggested that exposure 1 rated sub floor panels and rated sheathing be stored under tarp or roof with adequate air circulation to keep them protected from prolonged rain or snow.
The everyday sheathing used on the body of a roof is not rated for weather exposure so when exposed eaves and or rakes occur at the perimeter a different more expensive weather rated grade of plywood or osb must be used.
If exposure 1 rated panels and sheathing do get wet edge swelling may be experienced.
At exposed roof overhangs the sheathing must be rated for exposure to the weather.