Gutter Slopes and Roof Drainage

Roof area drained with gutter slopes

Recommended sizing of gutter slopes draining roofs:

Roof area
Gutter diameterSlope of
mminches0.5%1%2%
m2ft2m2ft2m2ft2
80 3 16 170 22 240 32 350
100 4 33 360 47 510 67 720
125 5 58 625 82 880 116 1250
150 6 89 960 126 1360 178 1920

The table is based on a rainfall intensity of 100 mm per hour (4 inches per hour). The anticipated rainfall intensity should always be checked with the local authorities.

Gutter Size vs. Downspout Size

  • 4" gutter -> 3" downspout
  • 5" gutter -> 4" downspout
  • 6" gutter -> 4" downspout

Related Topics

  • Water Systems - Hot and cold water service systems - design properties, capacities, sizing and more

Related Documents

Tag Search

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  • es: drenaje laderas techo
  • de: Pisten Dachentw√§sserung

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