Rain Gutter Slope Calculator

Working out gutter slope as a general rule gutter slope is set at 1 4 inch per 10 feet of guttering.

Rain gutter slope calculator.

This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end. 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. 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. 15 m is a practical maximum gutter length to be served by a downspout.

The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website. 2 count the number of downspouts drain pipes on your house building and enter the number in downspouts 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. If the length of the gutter is 10 5 metres 35 feet the amount of slope required is 1 25 cm 1 4 inch multiplied by 1 metres 3 5 feet which when rounded up is 2 5 cm 1 inch.

Calculate the gutter slope by dividing the length of the gutter needed by 10. For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e. 3 select gutter type. Place the line spirit level on the string.