I am in the process of building a deck on a cross-sloping grade. On one end of the deck the joists are roughly 15 inches off the ground, and on the other end I have an inch at most from the ground to the bottom of the joist which doesn't leave any room for the beam. I'm cantilevering the deck so I need to dig below grade to make room for the beam. Is it ok to dig out for the beam, and is this common practice in working with a sloping grade? Any advice would be appreciated. Thanks.