We are building a chicken coop on our yard, but we have no choice but to build it on a sloped grade (15 inch drop over 6 feet). We're weighing our options and wondering if anyone has built a "run" on an elevated platform. We plan to frame something similar to the Wichita Coop, but have it set off the ground on posts with a plywood floor. We plan to use sand as the substrate in the run (on top of the plywood). The run will be exposed to the elements (hardware cloth for protection). Does anyone have experience building this type of coop? Are there any flaws with this design (don't be shy). We were planning on putting a trap door on the floor of the run to remove sand, if necessary. We're primarily concerned about drainage.