Foundation is concrete or masonry which supports a building, including footings, stem walls, retaining walls, and grade beams. Foundation extending in the downhill direction is a foundation running downhill and approximately perpendicular to the uphill foundation. Hillside building is any wood frame building or portion thereof constructed on or into a slope steeper than three horizontal to one vertical. If only a portion of the building is supported on or into the slope, these regulations apply to the entire building. Uphill diaphragm edge is the edge of the diaphragm adjacent and closest to the highest ground level at the perimeter of the diaphragm.
Uphill foundation is the foundation parallel and closest to the uphill diaphragm edge.