The problem is do to the metal u-beam that the walls rest in, and the wall seams. Wind forces water to drip down the exterior of the walls, which gets in between the seams, collects in the metal u-beam, and then flows into the shed. The metal u-beam acts as a tray, collecting the dripping water. Solution: caulk, caulk, caulk. Unfortunately, there's nothing that can be done regarding the metal tray, where the water collects. Poor design that was not tested in rain.