How Many Downspouts On Long Gutter Run

How many downspout installations should your gutters have.

How many downspouts on long gutter run.

I wanted to make this instructable to show how i hid my gutter downspouts. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. In areas with heavy rainfall your installer may also determine that for optimal flow you want downspouts on each end of a gutter run even if it s only about 20 feet. Local gutter guys use the total roof surface and slope to determine gutter size and number of downspots.

Size downspouts to fit the gutter. As with gutters a downspout s capacity must match or exceed the expected runoff. For most homes this means installing spouts at either end of a gutter section. The typical recommendation is one downspout for every 20 to 30 feet of gutters.

The next factor to take into account is the pitch of your roof because the pitch will cause water to flow in a certain direction. 3200 square feet of roof is calculated as 3200 600 5 33 rounding up you would need 6 2x3 downspouts or 3200 square feet of roof is calculated as 3200 1200 2 67 rounding up you would need 3 3x4 downspouts one 2x3 downspout will drain 600 sq. Badair barry adair trec 4563 eifstx 39 october 5 2008 12 48am 6. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.

The rule of thumb for this slope is a vertical 1 2 inch for every 10 feet of horizontal run. The above recommendations assume that you have properly sized downspouts every 40 feet. 600sqft of roof surface per downspout or every 25 of gutter ymmv. One 3x4 downspout will drain 1200 sq.

The standard is about inch per 10 feet. The above recommendations assume that you have properly sized downspouts every 40 feet. First you must consider how many downspouts you will need. It took about two full days of work.

As with gutters a downspout s capacity must match or exceed the expected runoff. Most gutter installers add a downspout about every 20 or 30 feet of gutter although depending on the slope of your roof and the rooflines you may need more. There are many more important factors that can change this broad rule. Parts were pretty cheap i think total cost was only about 100.

Doubling the number of downspouts halves the required capacity for each. Increasing the pitch increases a gutter s handling capacity but the gutter may look askew over a long run. General rule around here is slope and area determines gutter size and approx. If we have to sum it up in a single rule gutters need a downspout around every 30 to 40 feet.