There are two popular construction methods for concrete retaining walls depending on the height of the wall. The first one is designed for walls under 2' in height. This type of wall is typically anchored in place using pilings. The second method involves using a poured concrete footing to support walls over 2' in height. The footing is normally offset so that the wall can withstand the substantial force of the soil that the wall is built to retain. In extreme circumstances other methods could be combined to deal with different situations.
Although permits are not always required for retaining walls under 4' in height, it is always advised that the homeowners check with their local development department to ensure that their construction plan complies with the local bylaws for their area.
Concrete frost walls are a type of foundation that typically extends 4' below grade. This type of wall is required if you are building a structure that is attached to an existing frost-protected building, for example, adding an attached garage or an addition to an existing building. A frost wall may also be required if you are building a shop larger than 55 sq/m (592 sq/ft) or a structure with a second story.