NCC 2025 Volume One F1D3 (Class 2 to 9); Volume Two H2D6(1)(a) (Class 1 and 10) · AS/NZS 3500.3:2025 Clause 3.7, Figure 3.7.4(C) and Appendix H (Figures H.1, H.4, H.6(a) and H.8)
A high-capacity overflow sump is one of the AS/NZS 3500.3 box gutter overflow devices that NCC 2025 calls up through Volume One F1D3 for Class 2 to 9 buildings and Volume Two H2D6(1)(a) for Class 1 and 10 (Part 7.4 excludes box gutters, H2D6(3)(b)).