Gutter Downspout Requirements

Doubling the number of downspouts halves the required capacity for each.

Gutter downspout requirements.

The number of downspouts will depend on the cross section dimension of the downspout material. Use the chart below to figure out how many extra downspouts you need. The above recommendations assume that you have properly sized downspouts every 40 feet. From chart 1 2 it is determined that a 9 5 in 241 mm half round gutter should be used.

A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. Gutters and downspouts need to be sized to accommodate anticipated water loads. Allow 1 square inch of downspout cross section for every 100 square feet of roof area. Come visit our selection of quality products.

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Welcome to gutter supply your online reference for gutters gutter machines gutter guards and accessories. From table 1 3 it is found that a4 in 102 mm downspout is required. Size downspouts to fit the gutter.

Divide 1600 sq ft 149 sq m by 160 sq ft sq in 2 3 sq m 100 sq mm to determine that each downspout should have a minimum area of 10 sq in 6470 sq mm. Poorly designed or installed gutters and downspouts can cause rainwater to pool around the base of the home or back up into the gutters.