How Many Downspouts On Long Gutter Run

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.

How many downspouts on long gutter run.

The standard is about inch per 10 feet. Badair barry adair trec 4563 eifstx 39 october 5 2008 12 48am 6. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. First you must consider how many downspouts you will need.

As with gutters a downspout s capacity must match or exceed the expected runoff. If the run is more than 35 feet long some specialists recommend installing the high point of the system. There are many more important factors that can change this broad rule. How many downspouts do i really need.

For most homes this means installing spouts at either end of a gutter section. Local gutter guys use the total roof surface and slope to determine gutter size and number of downspots. Parts were pretty cheap i think total cost was only about 100. As with gutters a downspout s capacity must match or exceed the expected runoff.

One 3x4 downspout will drain 1200 sq. I wanted to make this instructable to show how i hid my gutter downspouts. The above recommendations assume that you have properly sized downspouts every 40 feet. How many downspout installations should your gutters have.

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. The above recommendations assume that you have properly sized downspouts every 40 feet. The typical recommendation is one downspout for every 20 to 30 feet of gutters. Doubling the number of downspouts halves the required capacity for each.

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. It took about two full days of work. 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. 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. 600sqft of roof surface per downspout or every 25 of gutter ymmv. The rule of thumb for this slope is a vertical 1 2 inch for every 10 feet of horizontal run. If we have to sum it up in a single rule gutters need a downspout around every 30 to 40 feet.