A foundation for a building superstructure has a number of hollow foundation tubes laid horizontally on the ground and susceptible to degradation over time by contact with the ground. Each tube is protected by one or both of the following: (1) a reinforcement housed within the tube, shaped conformably to the interior of the tube, and resistant to degradation by contact with the ground; and (2) a membrane surrounding the tube, shaped conformably to the exterior of the tube, and resistant to degradation by contact with the ground. The tubes are arranged to form the footprint of a small building. In completing the building superstructure, other tubes, which need not have the same protection, are stacked on the foundation tubes. Degradation of the foundation tubes over time because of their contact with the ground is rendered inconsequential by the reinforcement or prevented by the membrane.