Sizing Of Roof Downspouts

Size downspouts to fit the gutter.

Sizing of roof downspouts.

If a roof s various drainage areas call for different size gutters go for the biggest one k style. Adding additional downspouts will require less gutter and downspout volume resulting in smaller gutters downspouts. 5 inch 5 520 square feet. The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website.

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. Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage. Downspouts should be constructed with conductor. The gutter and downspout size required is highly dependent on the amount of gutter and the spacing of the downspouts.

Then use the information below to see what size gutter you need. Please lower the maximum spacing between downspouts to see this effect. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Downspout sizing in sizing downspouts the following considerations apply.

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.