Interpretations and Statutory Requirements
Pages 6

Table 2 of the Approved Document states that a 100 mm diameter half-round rainwater gutter can drain an effective area of 37 m2 with sharp edged outlet of 63 mm diameter.

Size The capacity of the drainage system should be large enough to carry the expected fl ow

at any point in the system. Table 2 of Approved Document H3 gives typical fl ow capacities of common size gutters and outlets.