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  BU509 Sizing gutters and downpipes

BU509.jpgGutters and downpipes are the most common method of disposing of surface water from buildings.

To ensure that water is safely disposed of, gutters and downpipes should be sized and installed so that the expected amount of water can be controlled with minimal chance of water entering the building and minimal risk of uncontrolled spillage.

This bulletin covers:

  • statutory requirements
  • rainfall intensity
  • roof plane area
  • roof slope
  • flow capacity
  • gutter falls
  • position of bends
  • location and design of outlets
  • downpipes
  • external and internal gutters.

Publication date: April 2009 Keywords: drainage, gutter, roof, weathertight