How Many Downspouts Do I Need On My Gutter

Size downspouts to fit the gutter.

How many downspouts do i need on my gutter.

How many downspout installations should your gutters have. The rule is that a downspout must be present for every 40 feet of gutter. Doubling the number of downspouts halves the required capacity for each. 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.

If you want a neater look try burying the downspouts. The typical recommendation is one downspout for every 20 to 30 feet of gutters. But it a job many homeowners can do says mark weisman owner of mark s lawn and landscape in halethorpe maryland. 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. 3200 square feet of roof is calculated as 3200 600 5 33 rounding up you would need 6 2x3 downspouts. 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.

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. Once you add up the square footage of your roof you can then determine the number of downspouts. You can hire a professional to dig a trench and bury a drain pipe for about 12 to 25 a foot.

Expect to pay more if the route is obstructed by tree roots or pavement. Care must be taken to ensure the gutters are correctly sloped for proper drainage. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. 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.

So if you have a 50 foot long gutter you need two downspouts typically one at each end. 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. Use the chart below to figure out how many extra downspouts you need. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area.

The number of downspouts can be determined by the surface square feet of your roof. 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. 2 by 3 inches 600 square feet.

3 by 4 inches 1 200 square feet. If we have to sum it up in a single rule gutters need a downspout around every 30 to 40 feet. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.