A metal fin tube foundation includes a pair of coupled metal plates, each plate being comprised of a plurality of flat panels, wherein each panel is positioned at an angle relative to an adjacent panel, and each plate including a fin on each lateral end of each plate, wherein each fin overlaps a fin of the other metal plate forming two pairs of overlapped fins, wherein the plates are coupled along each of the two pairs of overlapped fins; wherein the plurality of panels of the coupled two metal plates form a closed perimeter polygon shape having an open interior and wherein each pair of overlapped fins form a combined fin element which extends away from the perimeter of the polygon.

A permanent frost protected shallow foundation footing for a building is assembled from a plurality of form parts arranged in a chain that is partially below ground level to form a foundation perimeter. The form parts are made of a lightweight material such as insulating foam material shaped as an elongated sectional unit with an overhang part overhanging a cavity part of an interior cavity. The interior cavity has an opening for receiving a concrete pour concurrent with a concrete pour of a floor. Open ends of the assembled sectional units abut each other in end-to-end alignment to form an elongated cavity inside the perimeter chain of form parts that is filled with concrete. The overhang part may have a foot shape that fits inside the interior cavity of another form part that may also have a foot shape for compact storage or transport prior to assembly.

A post-tensioning system that is configured for use with concrete wind turbine foundation designs to post-tension the foundations and reduce the amount of reinforcement steel that is needed compared to conventional non-post-tensioned, steel reinforced concrete foundation designs. In the case of an inverted T gravity foundation, the post-tensioning system described herein reduces the amount of reinforcement steel that is required by 30-40 tons.