[villagetinker]

First I would get a review of the design of your roof, and your trusses, especially if this is an older house. Back up north I was specifically told to NOT do roof over, sorry I do not recall the reason, and there was very little cost difference. I think the concern was that IF there was any damage to the roof or its supporting structure you would not know it since the old roof was not removed. You may also want to consult your insurance carrier, as they may have specific requirements to continue coverage.