This is best done by your architect engineer or building designer and should conform to the requirements of as nzs 3500 3 2003 plumbing and drainage.
Box gutter sump size.
The side with the maximum flow is used to size the box gutter.
The total flow is used to size the sump and overflow.
When determining the size of your rainhead you will need to consider such things as rainfall intensity occurrence use of the building and the size of the box gutter.
This free online box gutter calculator will calculate the size of box gutters and sumps with a side overflow in accordance with the australian plumbing code as nzs 3500 3 2003 part 3 storm water drainage.
Support the entire weight of the gutter and sumps when full of water as well as a trafficable load at any point in the gutter and sumps.
Overflow box gutters must have independent overflow provision discharging to the atmosphere.
Layout box gutters must.
Learn more how to storm water design for building sites.
Each box gutter run must discharge independently to ether a sump or directly out of the building without changing the size of the gutter or changing direction.