Roof Water Gutter Calculator

That is how much rain a roof can drain during the most intense rainfall.

Roof water gutter calculator.

The tools guide the user step by step allowing fast and simple roof drainage design whilst ensuring full compliance with bs en12056 3 rainwater drainage design standard. Refer to bsen 12056 part 3. Downspout sizes must not exceed the bottom width of the gutter. As a general rule gutter slope is set at 1 4 inch per 10 feet of guttering.

For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e. 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. Ask gutter suppliers what size gutters will be needed to handle that amount. So for a roof that is 5 m long with a height of 4 m and the roof width is 8 m which makes the half roof width 4m we can calculate the effective roof area like this.

The code limit is 150mm for dp s and 26 800 sq mm for flat eaves gutters the program will calculate the size and number of downpipes downspouts leaders required and the eaves gutter sizes for any roof. Measure the length of the gutter for downspout locations. Roof drainage layout and calculations. Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist.

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. Calculate effective maximum roof area b c 2 x length of roof area in m installation. The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website. Box gutter with rain water head at end of box gutter.

To limit the effects of thermal expansion in gutters 50 ft. 3 select gutter type. 2 count the number of downspouts drain pipes on your house building and enter the number in downspouts field. Divide the inch per hour watershed of the roof by the 5 minute rainfall intensity.

There is no limit to downpipe size or eaves gutter size. 15 m is a practical maximum gutter length to be served by a downspout. Roof drainage calculators our online tools have been designed with simplicity in mind removing the need for any prior specialist industry knowledge. These figures are based on a rainfall intensity of 75mm hr roof pitch not exceeding 50º gutters running full.

Calculate the area of a roof to work out how much guttering is required. That will show how much water a gutter will have to drain. This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end.