Abstract: A below grade, post-tensioned concrete foundation system for use in the construction of residential dwellings and other structures is described. The foundation includes a post-tensioned concrete floor slab formed on the soil base of a below grade excavation. Concrete foundation walls are formed on the perimeter of the post-tensioned floor slab. The weight of the superstructure of dwelling as well as the weight of foundation itself is distributed across the post-tensioned floor slab, thereby resisting the detrimental effects of expansive soils on the foundation.

Abstract: A support post for use in construction mounted to the floor with a base collar which is provided with spacer rings for height adjustment. The spacer rings are inserted into the base collar before the support post is in order to provide additional height for the support post as needed in the field.