/ BUILDING CODE OF AUSTRALIA: EXPLANATION
The illustration below depicts exits in a Class 5 building. As illustrated, D1.3 (b)(iii) does not allow a non-fire-isolated stair to directly connect three storeys unless the Class 5 building has a sprinkler protection system. However, the stair can pass through or pass by a third storey provided it does not provide access to or egress for and is separate to the additional storey.
In this example, the basement stair flight (part B) has a 60 minute FRL separation from part A stair 1. The remaining section of the stair connects ground and level 1 only. Stair 2 connects basement and ground floor only. Therefore both stairs will comply with D1.3. The separating construction between parts A and B of stair 1 must have no opening that could permit the passage of fire or smoke.