Slope in one direction is relatively easy to address, but a lot with cross-slope presents additional challenges. There are some pretty sizable extra expenses that come from extra excavation, extra framing to fur walls inside tall foundation, walls which act to retain dirt on the outside, wider window and door trim material, extra retaining walls to create some flat outdoor living space. Our biggest cross-slope project was a 22′ difference from right rear corner to left front corner. Most of this difference was dealt within the footprint/design of the house, but still required 12′ retaining walls. This lot’s cross-slope is not that severe at a mere 6′.