EN 12056-3 · Wyly–Eaton
Downpipe design based on roof area, covering and rainfall intensity
diameter to scale
Design
DN 90
Q per downpipe 2,88 l/s
utilisation 0 %
Q = A × r × C × f
Q_kap = 2,5·10⁻⁴ · 0,33^(5/3) · d^(8/3) · 0,65
The pitch does not enter into the flow calculation — rain falls vertically, so the plan area is what counts. The roof-plane area here is only for ordering the covering.
Design capacities
The design capacity is the theoretical capacity reduced to 65 %, the way the standard does for downpipes with branches and bends. The downpipe is designed to the next larger diameter, not an exact figure — the catalogue only has the DN 75 to DN 150 range. The app remembers your entered values in the browser.