Well I am going to seal the sides and back a little better and add some Expanded PVC to the tops of the cages, I will also have an expanded PVC bottom and it will have a litter dam 2" up on all sides. Under that I will have a UTH. the tray will be raised 1/8" and the UTH can be removed by a slit in the back if need be. Thanks to Chris Harper, it will be an awesome cage system! the reason for the expanded PVC is that the shelves in there (floor and top of each cage) is Press board, I really am into making cages last. It was just to perfect to pass up! and it was onlt $211 including tax. It was just so perfect, not to mention the only one in the 5 stores I went to that was big enough! (we were shopping for something alse, but I was looking for ideas).