Your floor has delaminated ie (the floor layers have seperated)
I was told by a caravan repair man to use Ronseal Wet Rot wood hardener , drill small holes in floor and inject this fluid into the holes, make sure it is not near any foam that is used to insulate the caravan as the foam will be attacked, I had the problem at the back of my caravan in the washroom area Fleetwood Crystal it is now OK.
Roger Brown, January 2008
