How Many Downspouts Are Needed For Gutters

Use the chart below to figure out how many extra downspouts you need.

How many downspouts are needed for gutters.

A general rule of thumb is one downspout per 20 feet of guttering but more may be necessary depending on the local weather the size of the drainage area and the design of the gutter system. How many downspout installations should your gutters have. 3 by 4 inches 1 200 square feet. 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.

Size downspouts to fit the gutter. The typical recommendation is one downspout for every 20 to 30 feet of gutters. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area.

Use the chart below to figure out how many extra downspouts you need. Rectangular 2 by 3 inches 600 square feet 3 by 4 inches 1 200 square feet. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area. There are many more important factors that can change this broad rule.

If we have to sum it up in a single rule gutters need a downspout around every 30 to 40 feet. First you must consider how many downspouts you will need. As with gutters a downspout s capacity must match or exceed the expected runoff. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.

Doubling the number of downspouts halves the required capacity for each. For most homes this means installing spouts at either end of a gutter section. The gutter troughs and downspouts must be installed with this pitch in mind so that water flows down instead of remaining stagnant in the gutter trough.