The depth shown of the box gutter is the depth at the upstream end.
Box gutter sump depth.
This will give a sump depth about 150mm.
The minimum size of a sump is 400mm x 200mm minimum width of box gutter and 150mm deep.
To determine the box gutter depth is the first and foremost step for sizing components and materials for the roof drainage system which includes the rain heads and the box gutters.
The theoretical down pipe diameter is shown for reference purposes only.
The outlet must be no further than the diameter of the outlet to the centre of the outlet.
These options give provisions for overflow to the box gutter.
Choose an available size or any other size and enter that for the calculation of the sump.
Box gutter gradients shall not be flatter than 1 200 for sole widths equal to or less than 600mm wide.
Choose an available dp size or any other size and enter that for the calculation of the sump.
This is a good size for the required flow.
The depth shown of the box gutter is the depth at the upstream end.
The line will correspond to a minimum box gutter depth.
Sump with high capacity overflow device.
Here is a step wise guide for you to help.
Starting at the gutter gradient intersection draw a line up the design graph for a freely discharging box gutter chart in your copy of the standard.