NCC 2025 Volume One F1D3 (Class 2 to 9); Volume Two H2D6(1)(a) (Class 1 and 10) · AS/NZS 3500.3:2025 Clause 3.4.5, Figure 3.5.5 and Table 3.5.2
Spreaders onto a lower roof are an AS/NZS 3500.3 provision (Clause 3.4.5) with no Housing Provisions equivalent, so under NCC 2025 this is the Volume One F1D3 method for Class 2 to 9 buildings and the Volume Two H2D6(1)(a) route for Class 1 and 10.