Excessive frame flexing/failure in the upper deck of our 5th wheel.discovered damage is 1. Sawdust on furniture in the bedroom and by entry door from living area to the garage at intersection of wall and floor. 2. Furniture rub marks on wall in bedroom from upper cabinets with driver side having bowed out base or molding where it sits on window valance. 3. Separation of night stands from wall in bedroom on both sides and a curved wall in front.  4. Squeaky floor in bedroom on drivers side between bed and closet 5. Wrinkles and separation from steps and wall in the upper deck 6. Wrinkles around frame of hallway window in upper deck 7. Exterior of RV underneath the nose along where pin box is located there is separation with screws coming loose/out. The outside cap moldings loose and flapping in the breeze while going down the road 8. Lag bolts in the front section of 5th wheel that hold the wall to the frame some were missing, some coming loose, and all were undersized. These issues can contribute to further frame cracking and king pin failure that may result in significant property damage or even death, putting our family and others on our highways at risk. Grand Design sent a service repair technician (SRT) to inspect. During inspection a crack in the frame was found and told that welding would be needed. Appointment made at authorized repair facility and now the needed repair is being denied due to the pin box movement is at their minimum tolerance, yet the frame failure still exists causing a safety concern. Grand Design is aware of frame failure in several models and has yet to issue a recall of the structural defects caused by under sizing the frames and using the wrong lag bolts, and denying the repairs that are covered under their extended 5 year frame warranty.