Modern caravans and motorhome floors are made of a sandwich construction. The floor is constructed of two sheets of thin plywood bonded to a styrofoam core. If the bond breaks down, delamination takes place so your caravan floor will then feels spongy as you walk across it. Delamination can be cured by injecting a specially formulated epoxy resin, this takes up the void and bonds the construction together. This kind of repair is a permanent solution and the end result will be stronger than when the floor was originally manufactured.