Something quite common in post-Katrina life is buildings spontaneously reflooding. As footboards are being installed with nail guns, sometimes they hit a water pipe. Cool thing is that they don't leak. After several months, the nail finally rusts away and all of a sudden water starts spraying in the wall cavity. Apparently it usually happens at 4:30-5:00 on a Friday afternoon. That way it has all weekend to totally flood the ground floor.