How To Size Number Of Downspouts Needed For Roof

Downspout sizing in sizing downspouts the following considerations apply.

How to size number of downspouts needed for roof.

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Also the gutter width in relation to height may also be adjusted. Downspouts should be constructed with conductor. Downspout sizes must not exceed the bottom width of the gutter.

If a roof s various drainage areas call for different size gutters go for the biggest one k style. Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage. Multiply the number of downspouts by square footage of each. The capacity of a sloped rectangular gutter may be approximated by using a gutter cross section area not less than that of a semicircular gutter and a depth to width ratio of at least 0 75.

Rectangular downspouts move slightly less water at 600 square feet for 2 by 3 inch or 1 200 square feet for a 3 by 4 inch downspout. 6 inch 7 960 square feet. To limit the effects of thermal expansion in gutters 50 ft. Then use the information below to see what size gutter you need.

5 inch 5 520 square feet. 15 m is a practical maximum gutter length to be served by a downspout. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. Doubling the number of downspouts halves the required capacity for each.

Size downspouts to fit the gutter. The size of the downspout should be constant through out its length.