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Valley Catchment

The capacity of a valley gutter is determined differently to standard gutters, which are flat or very near to flat. A valley is a gutter at the internal intersection of two sloping planes of roof cladding, where the roof pitch is more than 8°.

Because the minimum slope of a valley is more than 5.5°, the discharge rate is greater than that of a flat gutter. Roof pitch increases the rate of flow, and catchment area increases proportionately.

Research by Martin & Tilley, from CSIRO Australia, has been used to show the increase in Valley Catchment Capabilities.

With the pitch of the roof known, the maximum catchment is determined from the graph.

Valley Catchment Capabilities has been calculated by allowing for 10 mm freeboard and roof cladding interference.

 

 

Clause: 
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Clause Number: 
5.6.1
/cop/roof-drainage/valley-gutters#valley-catchment
Revision Category: 
0 - Clause Removed
Revision Detail: 

This clause had been replaced with the newly developed online tool in Valley Capacity Calculations.

Draft Clause: 
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