I Have I basement door (44" x 82") that drops 8' below grade, just out of flood plane, clay. What angle (or fraction of an inch per 8" rise) do I need for proper spec? The abutttment wall is fiberfill, poured concrete, in 2" polystyrene form. My home is in the foothills of Colorado (golden) I live in an unincorporated portion of Jefferson County and the building department provides very little help. I want this structure to pass the test of time. Any help would be very much appreciated.