How Many Downspouts Are Needed For Gutters

Poorly designed or installed gutters and downspouts can cause rainwater to pool around the base of the home or back up into the gutters.

How many downspouts are needed for gutters.

2 by 3 inches 600 square feet. First you must consider how many downspouts you will need. Use the chart below to figure out how many extra downspouts you need. 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.

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. 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.

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. Rectangular 2 by 3 inches 600 square feet 3 by 4 inches 1 200 square feet. There are many more important factors that can change this broad rule. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.

Size downspouts to fit the gutter. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area. The typical recommendation is one downspout for every 20 to 30 feet of gutters.

For most homes this means installing spouts at either end of a gutter section. As with gutters a downspout s capacity must match or exceed the expected runoff. Use the chart below to figure out how many extra downspouts you need.