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. Size downspouts to fit the gutter. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area. 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.

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. The typical recommendation is one downspout for every 20 to 30 feet of gutters. As with gutters a downspout s capacity must match or exceed the expected runoff. 2 by 3 inches 600 square feet.

Rectangular 2 by 3 inches 600 square feet 3 by 4 inches 1 200 square feet. For most homes this means installing spouts at either end of a gutter section. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area. Doubling the number of downspouts halves the required capacity for each.

How many downspout installations should your gutters have. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. 3 by 4 inches 1 200 square feet. Use the chart below to figure out how many extra downspouts you need.

First you must consider how many downspouts you will need. There are many more important factors that can change this broad rule. As with gutters a downspout s capacity must match or exceed the expected runoff.