How Many Downspouts Do I Need?

How Many Downspouts Do I Need?

Installing gutters isn’t usually a complicated process. But it’s more involved than simply buying some lengths of metal to attach to the eaves. You have to consider the drainage system network as a whole. The gutters have to catch the water that flows from the roof and other overhead areas, but it needs to drain it somewhere safe too.

That’s where downspouts come in. Downspouts take the water from the horizontal gutters and deposit it somewhere appropriate—preferably away from the building. But if the downspouts aren’t adequate, they won’t do their job. This could lead to damage to your home and property.

Installing the right number of downspouts is essential for an optimally operating gutter system. But how many downspouts do I need, you might wonder. If you have been researching gutters,  you have probably come across some guidelines and formulas for calculating how many downspouts you need. 

While the general recommendation is to install one downspout for every 25 to 35 linear feet of gutter, every situation is different. Learn more about downspout placement so that you make the most of your investment..

How Many Downspouts Per Foot of Gutter?

While most experts recommend placing a downspout attached to every 25 to 35 linear feet of horizontal gutter, there is plenty of leeway. Some roofers say that you can place downspouts every 40 feet, while others indicate that you should never have a downspout supporting more than 30 feet of water.

Why are there so many variations in the formula? Because gutters aren’t a one-size-fits-all scenario. The next time you drive across town, look at the variety in the roofing architecture in your area. Some roofs are almost flat, with long stretches of gutter. Others have various levels and slopes, with shorter gutters. 

What Affects How Many Downspouts You Need?

You’ll have to make adjustments to the general recommendation based on your roof’s slope, shape and design. Other factors that affect how many downspouts do I need per foot include the climate in your area.

Consider that the goal of a downspout is to funnel water from the gutters to the ground. As rain pelts the large, flat slope of the roof, it cascades into the gutters. This large volume of water needs to make its way down without overflowing from the gutter system. In extreme conditions, the flow and volume of water may be significant. The downspouts must be large enough, plentiful enough and installed correctly to handle drainage in mild and intense conditions. 

You may need more downspouts in areas with greater water flow. These include:

  • Steep slopes – Even small amounts of water can flow quickly down a steep slope. The gutter at the bottom must be large enough to accommodate the fast flow without splashing or overflowing. Extra downspouts are often necessary in these areas to prevent backup.
  • Large expanses of roof – Water that collects on a single surface flows downward at once and can overwhelm the gutters. Adding extra downspouts to spots below wide, open roofing eases the pressure in those areas.
  • Lower gutters on multi-level roofs – Depending on the location of your gutters, those on lower roof levels may end up taking the brunt of a heavy rainstorm because they collect the water that drains from the gutters and slopes above. Connecting gutters on multiple levels is important, and you’ll need enough gutters to support the unique drainage needs.
  • Valleys – Valleys where multiple slopes come together transfer a great deal of water. Therefore, you need downspouts that support the fast flow in these corners.
  • Low points – Wherever there is a dip in the architecture or gutters, water may collect. Reduce ponding and promote drainage by adding downspouts to low spots on the roof.
  • Corners – If you don’t install gutters at the corners, you’ll end up with gutter channels that have no outlet. A home with lots of corners usually needs lots of downspouts.


How to Make Sure Your Downspouts Can Handle the Load

Your gutters and downspouts need to be large enough to manage the drainage demand from your roof. The best way to make sure that the downspouts can handle the volume of water that’s common in your area is to work with a professional roofing company. An expert will know how to manage the intricacies of your architecture.

Proper installation of gutters and downspouts is vital. While they should be installed in a general horizontal position, gutters should be gently sloped toward the downspouts. If the gutter is sloped toward the end where there is no downspout, water can overflow and cause leaks and other moisture damage.

You can also add conductor or leader heads to the downspouts to enhance their efficiency. These accessories mount to the top of the downspout and look like funnels. Conductor heads allow you to create a larger opening where the gutter connects to the downspout. The water flowing through the gutter can enter the downspout more quickly, reducing backup and overflow issues.

Conductor heads can reduce clogging by allowing for air to enter the downspout along with the water and flush out debris. However, particles that enter the funnel can still get clogged further down the line. Make sure that you keep all downspouts and gutters clear even if you’re using conductor heads. This is especially important if you live in a forested area, where pine needles and leaves collect in the gutters.

Conductor heads work to control the water from heavy flow areas. They can also serve to collect drainage from more than one gutter. They also have aesthetic appeal and add traditional charm to the exterior of your home.

Make sure that the location where the downspouts empty can also handle the load of water. Use splash guards or extenders to ensure that water escapes at least 4 to 6 feet from the edge of the home. If you’re adding new downspouts, ensure that they don’t introduce too much water to one area of the yard. Adding gravel to the place where the water exits or running the downspout under existing structures prevents erosion and reduces pooling in your yard.

Can You Add Downspouts to an Existing Gutter System?

Maybe your gutters are in great shape, but you’ve noticed that you are having issues with drainage. Perhaps you see water splashing over the gutter on one side of the house or the soffits and fascia are rotting. You may need to add more downspouts.

Depending on the type of gutter that you have, you may be able to install new downspouts without completely replacing the gutter system. Look at the spacing of your existing downspouts. Which areas could be balanced by additional drainage?

Some homeowners are hesitant to add downspouts because they worry that they’ll detract from the curb appeal. When installing downspouts, look for unobtrusive spots, like corners and areas with vertical trim. If the downspout stands out too much, you can always paint it to match the home.

You can control the way that water drains from your roof by designing your gutter and downspout system properly. If you are getting a new roof or repairing an old one, contact us to learn more about protecting it with the right drainage system.

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