If it happens to be only one small area it is fixable. The problem is water leaking into the roof often ends up in many areas. Have you found the only problem area or one of many? That's what I recommend you try to determine before making any decision. If it's a widespread issue in many areas, it would probably cost way more to fix it than it's worth. If you determine it's a problem in one area, it can probably be fixed but I don't think anyone can tell you how without seeing it. Small areas of dry rot can be fixed with epoxy products designed to repair boat transoms that are wood. I have used "Git Rot" with success on about a 1 1/2 square foot piece of rotted flooring in a travel trailer I used to own.
CLICK HERE FOR MORE INFO ON GIT ROTI hope this helps you. Sorry this happened.
