Gutter Downspout Size Calculator

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.

Gutter downspout size calculator.

Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist. The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website. 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. 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.

Doubling the number of downspouts halves the required capacity for each. Start pressure length to the worst case and height difference. 3 more clicks will get a pump size if req d. 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.

We will use the larger of the two or 310 sq ft for our first calculation. Downspout sizing in sizing downspouts the following considerations apply. Metal era recommends that you verify all data obtained. Remember to save this spreadsheet to your own computer.

A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. Size downspouts to fit the gutter. As far as downspouts go they run at 2 x3 and 3 x4 in size or 3 or 4 inches in diameter. This calculator uses the equations that are laid out in the smacna handbook.

First we will find the maximum amount of rain that will be captured in gallons per minute. 2 4 gutter and downspout sizing and location calculations both metric and english units. 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. Gutter professionals have experience matching the gutters and the downspouts.

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. Northclad gutter size requirement calculator this calculator uses current data to calculate the required size of gutter as well as number and size of downspouts based on your input. Downspout sizes are based on table 1 3 dimensions of standard downspouts page 1 4 of the architectural sheet metal manual 7th edition.

Downspouts should be constructed with conductor.