how can i repair my caravan ace diplomat?

we have just brought a caravan really cheap.we knew it had a damp problem and brought to repair.all the front end around the three windows is soft and spoungy and we need to take it all out and replace.the problem is we need to know how the caravan is built does it have a frame work at the front,or is the frame in each corner and the template for the window cut out of wood and insulation and fixed to each corner of the frame work.and could anyone tell me what the frame work for the caravan is made of,is it timber or metal?we think its early 1990s