I have a floor in my 7 year old trailer that is soft in the busiest part of the trailer. You feel the support floorboard, but it is soft on both sides of it. The floor in that spot creaks like an old ...
OP needs to clarify. He said soft floor, leading many to believe a leak has weakened the floor. I read that the complaint is that the floor is just flexing in that location, possibly due to foam core breaking down and all the traffic. The fix isnt easy, so if the only real complaint is the creaking noise, and the noticeable flexing, I'd probably just live with it.