Roof Water Gutter Calculator

Divide the inch per hour watershed of the roof by the 5 minute rainfall intensity.

Roof water gutter calculator. Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist. Roof drainage layout and calculations. To limit the effects of thermal expansion in gutters 50 ft. 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.

That is how much rain a roof can drain during the most intense rainfall. Calculate the area of a roof to work out how much guttering is required. 3 select gutter type. These figures are based on a rainfall intensity of 75mm hr roof pitch not exceeding 50º gutters running full.

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. Refer to bsen 12056 part 3. That part of the gutter in which the angle obstructs the flow.

The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website. That will show how much water a gutter will have to drain. 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.

Box gutter with rain water head at end of box gutter. There is no limit to downpipe size or eaves gutter size. Downspout sizes must not exceed the bottom width of the gutter. 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.

Calculate effective maximum roof area b c 2 x length of roof area in m installation. For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e. 2 count the number of downspouts drain pipes on your house building and enter the number in downspouts field. Roof drainage calculators our online tools have been designed with simplicity in mind removing the need for any prior specialist industry knowledge.

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. 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. Ask gutter suppliers what size gutters will be needed to handle that amount.