How To Size Number Of Downspouts Needed For Roof

Doubling the number of downspouts halves the required capacity for each.

How to size number of downspouts needed for roof.

If a roof s various drainage areas call for different size gutters go for the biggest one k style. 15 m is a practical maximum gutter length to be served by a downspout. Downspouts should be constructed with conductor. Downspout sizing in sizing downspouts the following considerations apply.

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. 5 inch 5 520 square feet. 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. Downspouts of less than 7 00 sq in 4515 sq mm cross section should not be used except for small areas such as porches and canopies.

6 inch 7 960 square feet. Then use the information below to see what size gutter you need. Also the gutter width in relation to height may also be adjusted. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.

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. Adding additional sections of gutter reduces the length of each section and will reduce the gutter size. The size of the downspout should be constant through out its length.

Downspout sizes must not exceed the bottom width of the gutter. To limit the effects of thermal expansion in gutters 50 ft.