A term used, in a general way, to describe the structure below ground level. However, it is more correctly applied to describe the intermediate courses between top of concrete and the underside of the main wall when they are built in a number of reducing steps and known as Offset Footings. The purpose is to distribute wall loads evenly and to achieve this the bottom course must be twice the thickness of the main wall and then each subsequent course is set back 56mm until the final thickness of the wall above is reached. Offset Footings are built entirely in Header Bond (now rarely used).