Use the chart below to figure out how many extra downspouts you need.
How many downspouts do i need on my 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.
Doubling the number of downspouts halves the required capacity for each.
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.
The gutter troughs and downspouts must be installed with this pitch in mind.
Particularly wet climates could require better drainage systems than relatively dry climates rainy.
Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area.
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.
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.
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.
As with gutters a downspout s capacity must match or exceed the expected runoff.
Gutters come in many sizes.
Smaller gutters may need extra downspouts to make up for their low volume.
2 by 3 inches 600 square feet.
3 by 4 inches 1 200 square.
Buried or underground roof drainage downspout defects clogging overflowing holes corrosion leaks that cause wet basements or crawl areas proper installation of buried downspout extensions proper installation of french drains seepage pits at flat sites gutter downspout defects cause wet basements crawl areas questions answers about installing maintaining repairing buried roof.
How many downspouts do i really need.
One 3x4 downspout will drain 1200 sq.
The typical recommendation is one downspout for every 20 to 30 feet of gutters.
First you must consider how many downspouts you will need.
Heavy rainstorms put a lot more pressure on gutters.
Use the chart below to figure out how many extra downspouts you need.
Large gutters can hold more water and may not need as many spouts.
As with gutters a downspout s capacity must match or exceed the expected runoff.
Size downspouts to fit the gutter.
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.
Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.
Or 3200 square feet of roof is calculated as 3200 1200 2 67 rounding up you would need 3 3x4 downspouts one 2x3 downspout will drain 600 sq.
Expect to pay more if the route is obstructed by tree roots or pavement.
You can hire a professional to dig a trench and bury a drain pipe for about 12 to 25 a foot.
If you want a neater look try burying the downspouts.
