Although preserved wood frame foundation systems have been accepted for only a relatively short period of time, their use has increased steadily and now represents a significant portion of the market. Since the success of this systems depends on the effectiveness of the preservative treatment, it is important that only wood that has the required preservative retention be used and that any portions affected by field cutting or drilling be treated with preservatives. The system's adequacy to resist both earth pressure loads and loads from the superstructure can only be assured by paying strict attention to details that have been developed to resist such forces. Aids are available for smaller buildings which simplify the selection of design details and these should be followed faithfully if the foundation is to perform as intended.