How a house is built
Leveling a sloping lot
How a sloping lot is cut and filled to make a level pad, and why the soil under the house is not topsoil.
Arrow keys turn the house. Plus and minus, or the zoom buttons, change the zoom. A horizontal drag turns it after you tap the drawing. Reset view returns to the step camera.
The drawing needs WebGL. The notes on the page still stand.
On a slope the house wants a level pad. Soil taken from the high side is the cut. Soil placed on the low side is the fill. The volumes are rarely equal once organic soil is stripped and the fill is compacted.
Fill that will carry a footing is placed in layers and compacted. Topsoil, stumps, and debris do not belong in that fill. They settle. A soils report, when the site needs one, says what the ground can carry and whether the fill is allowed under the house.
This model is already a flat pad. It shows the result, not the hillside and not a grading plan.