NCC 2025 Volume One F1D3 (Class 2 to 9); Volume Two H2D2(1)(a) (Class 1 and 10) · AS/NZS 3500.3:2025 Clause 5.4.9 (Manning's equation); hazard classes from Australian Rainfall and Runoff (Version 4.2), for information
NCC 2025 calls up AS/NZS 3500.3 for stormwater drainage (Volume One F1D3 for Class 2 to 9 buildings, Volume Two H2D2(1)(a) for houses and Class 10 buildings), and this calculator applies its Manning's equation and 300 mm floor check; the hazard class comes from Australian Rainfall and Runoff, for information.