The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website.
Rain gutter slope calculator.
15 m is a practical maximum gutter length to be served by a downspout.
This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end.
Place the line spirit level on the string.
To limit the effects of thermal expansion in gutters 50 ft.
For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e.
This calculator uses current data to calculate the required size of gutter as well as number and size of downspouts based on your input.
2 count the number of downspouts drain pipes on your house building and enter the number in downspouts field.
Working out gutter slope as a general rule gutter slope is set at 1 4 inch per 10 feet of guttering.
How to use the calculator 1 measure the length of your gutters along the eaves of your roof and plug in the number in the length field.
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 hand prior to ordering or installing your gutter system.
3 select gutter type.
Calculate the gutter slope by dividing the length of the gutter needed by 10.