It appears to me, while being built at the factory someone forgot to secure that piece of plywood to the roof rafters. As far as the slider floor is concerned, I think that is a design flaw. Two things here also. The weight of the flex steel sofa/bed is too heavy for the long unsupported floor (over12 feet) and when the slider is in and slightly up at floor level, the sofa flexes the floor too much as you are driving down the roads. After checking another large Sabre 5th wheel the design of that slider (the same as mine) allows the floor edges at either end to be exposed to the weather elements. There should have been an aluminum angle attachéd at each end to protect the exposed floor. (IMHO) The bedroom slider has the angle metal to protect the ends of the floor plywood.