Roof Water Gutter Calculator

Measure the length of the gutter for downspout locations.

Roof water gutter calculator.

Downspout sizes must not exceed the bottom width of the gutter. This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end. Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist. That part of the gutter in which the angle obstructs the flow.

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. Refer to bsen 12056 part 3. Simplified suitable for flattish roofs with little or no vertical faces or steep roofs draining to one side of box gutter only or any roof if you are in a hurry and make the necessary allowances for all catchments. Calculate the area of a roof to work out how much guttering is required.

For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e. 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. To limit the effects of thermal expansion in gutters 50 ft. That will show how much water a gutter will have to drain.

Ask gutter suppliers what size gutters will be needed to handle that amount. 15 m is a practical maximum gutter length to be served by a downspout. These figures are based on a rainfall intensity of 75mm hr roof pitch not exceeding 50º gutters running full. Roof drainage layout and calculations.

Roof drainage calculators our online tools have been designed with simplicity in mind removing the need for any prior specialist industry knowledge. There is no limit to downpipe size or eaves gutter size. 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. That is how much rain a roof can drain during the most intense rainfall.

The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website. Calculate effective maximum roof area b c 2 x length of roof area in m installation. 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. 2 count the number of downspouts drain pipes on your house building and enter the number in downspouts field.

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. 5m x 4m x 4 2 40 square metres. Divide the inch per hour watershed of the roof by the 5 minute rainfall intensity.