How Many Square Feet Of Roof Per Downspout

If we have to sum it up in a single rule gutters need a downspout around every 30 to 40 feet.

How many square feet of roof per downspout.

3 inches 706 square feet. After you have calculated the square footage use following calculations. Up to 6 12 7 12 8 12. For most homes this means installing spouts at either end of a gutter section.

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. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. This nominal square footage amount is then multiplied by a factor associated with the roof s pitch. 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. Doubling the number of downspouts halves the required capacity for each. Roof area square feet per linear ft of gutter underneath. 4 inches 1 255 square feet.

Many factors can effect the proper size of gutter. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area. Most of all is location and your average rainfall during a large downpour. Gutter and downspout water capacity.

A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. Your roof is without a doubt one of the most important elements of your home. 2 by 3 inches 600 square feet. For the vast majority of rains gutter and downspouts.

Use the chart below to figure out how many extra downspouts you need. 3 by 4 inches 1 200 square feet.