The clause provides a concession for a building with a rise in storey of two to adopt a lower type of construction than required in clause C2D2 (C1.1). The concession allows for buildings which are solely class 2, solely class 3, a mixture of class 2 and 3 or solely class 9c to adopt type C construction when certain conditions are met.
The clause does not allow for the concession to be applied when there is another class of building. For example, class 7a carpark or class 6 shop. The Australian Building Codes Board (ABCB) video below explains how the concession works.
Buildings A, B and C are examples of buildings with a rise in storey of two where the concession can be applied.
Building D, E and F are example of buildings with a rise in storey of two that the concession cannot be applied to. The buildings do not solely contain class 2, class 3 or a combination of class 2 and 3. Building D and F have a class 7 part, while building E has a class 6 part.