If the floor has got damp then you need to get it dried out obviously. There are many ways to do that as other comments have documented or you can regularly keep heating the caravan and yank up the carpets. But if you find that you now have a bouncy floor like we did then you will need to get down the caravan store and buy a delamination kit and go through the process as discribed on the kit. Unless you don't give a monkeys about the weight and condition of the caravan, in which case you can just wedge some wood underneath between the axel.
Hope this is some help to somebody
matty
September 2008