Flow rate calculator

Design and Installation
To select the gutter size appropriate to your requirements, two factors must be taken into consideration.

- Roof area
- Gutter Flow Capacity

For further reference refer to
BS EN 12056-3:2000 ‘Roof drainage, layout and calculation'. 

Roof Area
The effective roof area can be calculated by using the following formula:
(B + C) x length of Roof =Area in M2 
       2 

Gutter Flow Capacity
Gutter flow capacity is dependent upon system type, outlet position and whether gutter is laid level or to a specified fall. The table above gives the required information based upon a Rainfall intensity of 75mm per hour and recommendations from BS EN 12056-3:2000. 

Flow Rate Calculator