The flow capacities for standard Guttercrest gutters are based on :-

The calculation methods in BSEN12056-3:2000. Rainfall intensity varies geographically with the highest levels in the South-East of England, over a range 0.01 to 0.022 I/(s.m.2)

The gutters being laid nominally level. This design rate is generally suitable for eaves gutters where overflow is unlikely to occur inside or damage the fabric of the building.

As each rainwater system is unique, consideration must be given that angles, roof pitch, etc effects the flow rates.

IF YOU REQUIRE A FLOW CALCULATION PLEASE CONTACT OUR TECHNICAL DEPARTMENT