Calculate Rainwater Gutter Size

To limit the effects of thermal expansion in gutters 50 ft.

Calculate rainwater gutter size.

To determine the design area multiply the plan area by the factor in b column these areas are then divided by the proper factor given in table 1 2 thus obtaining the required area in square inches square mm for each downspout. If gutters don t slope water gathers in them. Boasting considerable experience spanning over 25 years gutter masters company has operated on different buildings scenarios and designs with success at each turn. Cost calculator rain gutter installation calculator.

Doubling the number of downspouts halves the required capacity for each. The gutter slope also called the pitch is the amount the gutter tilts down to let rainwater flow out of it. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist.

15 m is a practical maximum gutter length to be served by a downspout. Roof often leads to oversizing of gutters downspouts and drains. However in areas like san diego orange county and other parts of southern california we are often praying for rain and do not seem to get enough rainfall to cause builders to automatically add a. Downspout sizes must not exceed the bottom width of the gutter.

To determine the design area for a pitched roof table 1 1 is used. In many parts of the country rain gutters are an absolute must and are integral in keeping water out of basements and preventing damage to homes. Proper gutter and downspout sizing rainfall intensity downspout capacity. From table 1 3 select the downspout.

To determine the design area multiply the plan area by the factor in b column these areas are then divided by the proper factor given in table 1 2 thus obtaining the required area in square inches. If gutters slope too severely they don t hold water and water could splash over the sides in heavy rain. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. The amount of collected water increases until it spills over the sides of the gutter.

Box gutter with rain water head at end of box gutter. Size downspouts to fit the gutter. Subtracting 3 4 for under the roof edge and 1 8 outside edge allowance this is the width that is available for the rainwater to enter the gutter total width of a flat piece of building material maximum total gutter drop before any downspout this assumes 4 7 per hour maximum rain intensity.