Cathy, I've found the best search engine is this one: Google Custom Search - Fiberglass RV Forum Custom Search
it's really the only one I use. If you search for "replacing floor" you'll probably get more hits than you want. Remember, the more defined the search, the fewer the hits. Here's a search about replacing portions of the floor: floor rot replace - Google Search
floor rot replace
in the search engine. I know there are others, but this is a start.
The good thing about the custom search engine is it searches all the forums on FiberglassRV, not just the individual forum you think you'll find the information you're seeking.
Hope it helps.