My Minnie has a common RV construction flaw, which may also point to your problem. Along the entire bottom of my exterior walls is a plastic "C"-shaped trim piece, with the opening pointing up. This gives a fairly neat look to the otherwise rough-looking end of the wall material along the bottom. The problem is that this "C" holds water, which eventually wicks up into the walls, causing delaminaion. There are drain holes, but too few, too far apart, too small, and too ineffective. Around the wheel wells there will be additional water thrown up by the turning wheels, which can make this an area susceptible to faster delam, as is the case on mine. My Minnie also suffers from extensive manufacturing errors of missing or misplaced caulking, that caused delam and rot in other areas.