Gutter And Downspout Design Calculations

Adding additional sections of gutter reduces the length of each section and will reduce the gutter size.

Gutter and downspout design calculations.

There are two major factors to consider when deciding a gutter design. Downspouts and gutters are sized in relation to rainfall on this basis. With 1 gpm 0 063 l s flow rate. This wizard makes it easy to calculate the roof design area by providing various shape calculations and the calculation for vertical walls area per international plumbing code ipc.

Roof in the calculation of a drainage system. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. 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. To limit the effects of thermal expansion in gutters 50 ft.

15 m is a practical maximum gutter length to be served by a downspout. To determine the design area for a pitched roof table 1 1 is used. Size downspouts to fit the gutter. 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.

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. The first is to make it wide and deep enough to collect all of the rainwater during the hardest rainfall. 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.