Gutter Downspout Size Calculator

Now that we are well aware of the various gutter downspout sizes and styles let us dig deeper into the materials used for effective downspouts and how much they shall cost.

Gutter downspout size calculator.

Start pressure length to the worst case and height difference. Downspout sizing in sizing downspouts the following considerations apply. As far as downspouts go they run at 2 x3 and 3 x4 in size or 3 or 4 inches in diameter. Downspouts should be constructed with conductor.

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. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. 3 more clicks will get a pump size if req d. Water pipe size calculator information video water pipe size calculators size every pipe in your project in seconds with just 3 clicks.

The size of the downspout should be constant through out its length. 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. Remember to save this spreadsheet to your own computer. The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website.

This calculator uses the equations that are laid out in the smacna handbook. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. This calculator serves as an information source only. Downspout sizes are based on table 1 3 dimensions of standard downspouts page 1 4 of the architectural sheet metal manual 7th edition.

For example a 6 inch k style gutter requires a 3 x 4 downspout while a 5 inch k style gutter uses a 2 x 3 downspout. Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist. Gutter professionals have experience matching the gutters and the downspouts. Metal era recommends that you verify all data obtained.

We will use the larger of the two or 310 sq ft for our first calculation. We recommend using this calculator as a basic tool to begin determining the requirements for your drainage system however all information should be verified by. The second most common style of downspouts in urban homes is the rectangular downspout coming under a range of sizes such as 2 3 3 4 and 4 5. 2 4 gutter and downspout sizing and location calculations both metric and english units.

First we will find the maximum amount of rain that will be captured in gallons per minute.