Leak Repairs - Tile Valley Obstructed Leaking on Bottom   « « BACK « « This long, diagonal channel is a valley on a tile roof. Valleys are a common source of leakage on sloped roofs. This particular leaking valley has begun to deteriorate the plywood and created a collapse at the bottom. Leaves clogging the valley have also accelerated the damage. Repairing a leaking valley requires the entire valley to be done.