I am purchasing a home. After the purchase offer was accepted, the physical inspection revealed that portions of the roof sheathing were delaminated and the rafters were discolored due to significant moisture in the attic caused by a bathroom exhaust fan which was venting into the attic. I agreed to continue with the purchase after the owners agreed to an addendum to the purchase offer requiring them to install a new roof to include sheathing/decking. I recently got a copy of the contract with the roofer and discovered that new plywood will be installed over the existing damaged plywood. The damaged sheathing will not be replaced. Is this an adequate repair for this problem. What plywood thickness should be used. I am very concerned. The roof is due to be installed in 1 week. Help! I know nothing about these things. I'd appreciate any advice.

Spanning new over old is fine.

rdh