This weekend we had JPA Construction in nearby Hyannis reroof Old Farm. A terrific company to work with as we asked for quick upgrades on framing/parts original to the house and a newer three flued chimney. I found enough (out of stock) GAF HDZ Timberline "Shakewood" color high grade shingles from "Landis" in Hyannis, to best match the house and other buildings. The South facing roof has 2 layers of staggered plywood over 1" old sheathing boards, and the North side only needed one. Lead flashing was replaced around the chimney and 2 1/2" copper drip edges were added to the rakeboards.
Now the exposed old framing and sheathing remains while well secured.