How Many Square Feet Of Roof Per Downspout

3 inches 706 square feet.

How many square feet of roof per downspout.

Roof pitches in degrees. 3 by 4 inches 1 200 square feet. Many factors can effect the proper size of gutter. After you have calculated the square footage use following calculations.

Use the chart below to figure out how many extra downspouts you need. Your roof is without a doubt one of the most important elements of your home. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. This nominal square footage amount is then multiplied by a factor associated with the roof s pitch.

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Roof area square feet per linear ft of gutter underneath. Most of all is location and your average rainfall during a large downpour. As an example if your overhang is 12 inches you ll add 2 feet to the overall length and 2 feet to the overall width of the house.

To do that simply multiply drainage area calculated earlier by roof pitch factor and rainfall intensity. 4 inches 1 255 square feet. For the vast majority of rains gutter and downspouts. 2 by 3 inches 600 square feet.

Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area. Doubling the number of downspouts halves the required capacity for each. Up to 6 12 7 12 8 12. If we have to sum it up in a single rule gutters need a downspout around every 30 to 40 feet.

For a 5 inch k style gutter the square footage should be up to 5 500 sq ft and for a 6 inch k style gutter the square footage should be upto 7 900 sq ft. Gutter and downspout water capacity.