Gutter And Downspout Design Calculations

To limit the effects of thermal expansion in gutters 50 ft.

Gutter and downspout design calculations.

Size downspouts to fit the gutter. Adding additional sections of gutter reduces the length of each section and will reduce the gutter size. With 1 gpm 0 063 l s flow rate. Roof in the calculation of a drainage system.

To determine the design area for a pitched roof table 1 1 is used. There are two major factors to consider when deciding a gutter design. Experience has taught that use of the true area of a pitched roof often leads to oversizing of gutters downspouts and drains. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.

The first is to make it wide and deep enough to collect all of the rainwater during the hardest rainfall. Downspout sizes must not exceed the bottom width of the gutter. Table 1 1 design areas for pitched roofs pitch in ft. The gutter and downspout size requirement depends upon the number of sections and length of the gutter sections as well as the number of downspouts.

Plumbing codes typically use the vertically projected roof area for drainage design and they often use a square foot allowance per square inch of downspout for 1 in hr 25 mm hr rainfall that varies with diameter for example 3. 15 m is a practical maximum gutter length to be served by a downspout. This spread sheet will help you calculate the gutter width and maximum distance between downspouts based on your maximum rainfall roof area and style of gutter. Doubling the number of downspouts halves the required capacity for each.

Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist.