NCC 2025 Volume Two H2D6(1)(b) · Housing Provisions Part 7.4 (Class 1 and 10, not Victoria)
To size to AS/NZS 3500.3:2025 (required in Victoria, for box gutters and for a type F result), use the eaves gutter and gutter overflow calculators.
Design rainfall 201 mm/h at 5% AEP · 262 mm/h at 1% AEP (Table 7.4.3d).
Plan area of roof draining to this one downpipe (tables cover up to 70 m²).
Eaves gutter length this downpipe drains — max 12 m.
Continuous overflow measuresper metre of gutter
Dedicated overflow measuresper downpipe
Enter the roof catchment area to draw the overflow gauge.
Enter the dimensions above to evaluate compliance.