There is a piece of trim on the floor that covers the edge of the rubber floor material and has an L shape so it covers the edge of the outside siding. I removed this trim and diagnosing the problem did not take long. When the factory cut the hole in the siding for the rear door they screwed up. They left the lower right edge too high. The siding edge should be level with the interior floor. At the lower right side it is higher than the floor. When screwed down the trim places pressure on the vertical siding edge and also raises slightly because the siding prevents the trim from resting on the floor. Because the trim is not flush with the floor the door rubs the trim when closed and adds more pressure to the siding. It cracked from the pressure.
The other problem is with the metal door frame. There is a square metal tube that runs along the floor under the rubber. The trim screws go into this metal. It provides support for the trim and the outside siding rests against this tube. The L of the trim holds the edge of the siding firmly against the metal. Except for about an inch or so on both sides. There is no support in the corners. So not only did the siding crack but it started folding inward into the open area. I was able to bridge this gap with a small thin piece of strap metal.
I cut the edge lower so there there is no pressure on the vertical edge of siding when the trim is installed. A length of about 8 inches had to be cut shorter. The repair is not perfect. But I think I have stopped the spread of the crack and I have certainly fixed the factory problem.
Another stupid problem caused by careless assembly. I've never had so many problems with an RV.
You may be interested in the next article, Another Leak.
The previous article is Split Loading Ramp Door.
© Bobby Daniel