How Many Square Feet Of Roof Per Downspout

Most of all is location and your average rainfall during a large downpour.

How many square feet of roof per downspout.

Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area. To do that simply multiply drainage area calculated earlier by roof pitch factor and rainfall intensity. Gutter and downspout water capacity. If we have to sum it up in a single rule gutters need a downspout around every 30 to 40 feet.

Roof pitches in degrees. 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. For most homes this means installing spouts at either end of a gutter section. 3 inches 706 square feet.

Roof area square feet per linear ft of gutter underneath. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Many factors can effect the proper size of gutter. 3 by 4 inches 1 200 square feet.

This nominal square footage amount is then multiplied by a factor associated with the roof s pitch. Your roof is without a doubt one of the most important elements of your home. After you have calculated the square footage use following calculations. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.

2 by 3 inches 600 square feet. 4 inches 1 255 square feet. Up to 6 12 7 12 8 12. Doubling the number of downspouts halves the required capacity for each.

Use the chart below to figure out how many extra downspouts you need. How many downspout installations should your gutters have.