We are currently having cedar siding taken off our house in order to put up Hardie Plank. Some of the OSB under the old siding has water damage, and is being replaced. Our contractor has left the new OSB exposed, and hasn't been back over yet to put the Fanfold and Tyvek over the new OSB in two weeks, saying this is a better grade of OSB that won't be damaged by the rain. This doesn't sound right to me....