NCC 2025 Volume One F1D3; Volume Two H2D2(1)(a) · AS/NZS 3500.3:2025 Clause 7.10 for construction; storage by the modified rational method, as councils apply it (not an NCC method)
NCC 2025 does not set on-site detention: the council sets the permissible site discharge and storage, this calculator estimates them by the modified rational method many councils use, and the construction rules come from AS/NZS 3500.3 Clause 7.10, which NCC 2025 calls up through Volume One F1D3 and Volume Two H2D2(1)(a).