What is the minimum footing depth for Group A dwellings under PD 1096?

The correct minimum footing depth for Group A dwellings under PD 1096 is 600 mm. This depth requirement is established to provide adequate support for the structure, accounting for factors such as soil bearing capacity, the load of the building, and local environmental conditions. A footing that is too shallow may lead to foundation settlement or instability, which can ultimately compromise the safety and integrity of the dwelling.

While the other options listed provide different depth requirements, they do not meet the standards set forth in the guidelines for Group A dwellings. The specified depth of 600 mm ensures that the footings are sufficiently deep to resist potential heaving and shifting that can be caused by moisture changes in the soil as well as to bear the weight of the structure effectively.