Pier foundations

Piers Can Support Anything From a Deck to a House

For use with unusual soils or steep slopes

Disturbing as little soil as possible
Pier foundations are unlike more conventional concrete footings and walls in that they support structural loads at a number of distinct points, not continuously. Pier foundations can be as simple as concrete-filled cardboard tubes dropped into hand-dug holes. But more complex foundations incorporating very deep piers or helical screws can support much greater loads.
To some green builders, one advantage of pier foundations is that they require less excavation and soil disruption than any other foundation type.