5 inch 5 520 square feet.
Sizing of roof downspouts.
The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website.
Downspout sizing in sizing downspouts the following considerations apply.
Adding additional downspouts will require less gutter and downspout volume resulting in smaller gutters downspouts.
Now architects engineers designers and contractors can easily and accurately size downspouts and gutters according to the specifications in smacna s architectural sheet metal manual 7th edition 2012.
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.
Downspouts should be constructed with conductor.
Then use the information below to see what size gutter you need.
Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.
The gutter and downspout size required is highly dependent on the amount of gutter and the spacing of the downspouts.
Size downspouts to fit the gutter.
Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage.
If a roof s various drainage areas call for different size gutters go for the biggest one k style.
A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.