Gutter And Downspout Design Calculations

Size downspouts to fit the gutter.

Gutter and downspout design calculations.

With 1 gpm 0 063 l s flow rate. Doubling the number of downspouts halves the required capacity for each. 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. 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.

To limit the effects of thermal expansion in gutters 50 ft. 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. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. To determine the design area for a pitched roof table 1 1 is used.

Downspouts and gutters are sized in relation to rainfall on this basis. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. There are two major factors to consider when deciding a gutter design. 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. 15 m is a practical maximum gutter length to be served by a downspout. Adding additional sections of gutter reduces the length of each section and will reduce the gutter size. Roof in the calculation of a drainage system.

Experience has taught that use of the true area of a pitched roof often leads to oversizing of gutters downspouts and drains.