Adding additional sections of gutter reduces the length of each section and will reduce the gutter size.
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.
A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.
To limit the effects of thermal expansion in gutters 50 ft.
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.
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.
The size of the downspout should be constant through out its length.
Downspout sizing in sizing downspouts the following considerations apply.
Doubling the number of downspouts halves the required capacity for each.
Downspout sizes must not exceed the bottom width of the gutter.
Also the gutter width in relation to height may also be adjusted.
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.
5 inch 5 520 square feet.
15 m is a practical maximum gutter length to be served by a downspout.
If a roof s various drainage areas call for different size gutters go for the biggest one k style.
Downspouts should be constructed with conductor.
6 inch 7 960 square feet.
Size downspouts to fit the gutter.