How Many Downspouts Do I Need On My Gutter

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

How many downspouts do i need on my gutter. The rule is that a downspout must be present for every 40 feet of gutter. 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. 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. But it a job many homeowners can do says mark weisman owner of mark s lawn and landscape in halethorpe maryland.

A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. For most homes this means installing spouts at either end of a gutter section. 2 by 3 inches 600 square feet. The number of downspouts can be determined by the surface square feet of your roof.

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. Doubling the number of downspouts halves the required capacity for each. So if you have a 50 foot long gutter you need two downspouts typically one at each end. First you must consider how many downspouts you will need.

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. Expect to pay more if the route is obstructed by tree roots or pavement. As with gutters a downspout s capacity must match or exceed the expected runoff.

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

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 we have to sum it up in a single rule gutters need a downspout around every 30 to 40 feet. Care must be taken to ensure the gutters are correctly sloped for proper drainage. As with gutters a downspout s capacity must match or exceed the expected runoff.

Poorly designed or installed gutters and downspouts can cause rainwater to pool around the base of the home or back up into the gutters. Use the chart below to figure out how many extra downspouts you need. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. The typical recommendation is one downspout for every 20 to 30 feet of gutters.

If you want a neater look try burying the downspouts. 3 by 4 inches 1 200 square feet. Size downspouts to fit the gutter.