The Electricity Trust of South Australia is to construct a sub-station at Mount Barker. The single storey building of about 39 squares will be of modular block construction. The site was explored by 2 test pits 7 and 8 feet deep. The ground surface at the site is gently sloping (at about 3°). The ground surface if formed of organic sandy silt. The test pits showed this topsoil to be about 0.7 feet thick overlying red-brown clay soil of high plasticity, developed over weathered sandstone and schist bedrock. Rock is 2.6 feet below the ground surface in Pit 1 and 1.7 feet in Pit 2. The upper 1 feet of rock is extremely weathered to a clay soil of low plasticity, sandy in parts. The clay soil horizon developed over bedrock, in Pit 2 is reason-ably strong but the similar horizon in Pit 1 is much weaker. In both pits it appears to be of the expansive type, that is, subject to seasonal swelling and shrinking movements of fairly severe magnitude. Several alternative footing types, which have proved suitable for domestic homes under similar conditions, are described.