We tend to focus a lot on our home’s gutter system, and for good reason: poorly maintained gutters lead to roof damage, overflows, rotting fascia, ice dams, and more. But while those horizontal gutters usually hang in the limelight, it’s the downspouts that do the important work of carrying that water to the ground and away from your house.
Downspouts also get clogged, form leaks, wiggle loose, experience damage, or end up depositing too close to the foundation. And, water that’s close to the foundation can create much, much bigger problems.
The number of downspouts your home has, as well as the size, placement, and extension all affect how well your home handles rainwater. So, if you’re new to your home or experiencing water issues, take the time to spot problems before fall leaves, freezing temperatures, and winter weather make them worse.
The Best Downspout Layout for Your Home
When you’re auditing your system, think about the roof runoff—it probably doesn’t run off evenly all around, unless your home is a perfect square, and even then, only if the rain is coming straight down. On most homes, you can expect that a few of the gutters and downspouts handle the majority of the water. Not coincidentally, mitigating water damage around these downspouts might be trickier.
"As a baseline, you want one downspout for every 30 to 40 feet of guttering,” explained Anthony Davis, VP of Training and Development at Groundworks. “A good rule of thumb is that if you’re seeing water spill over the gutter, but they are clean, clog free, and firmly attached to the fascia board, that can be a sign you need additional downspouts."
The design of the system matters, as does the physical size of the downspout. A downspout can be in good condition and completely clear but still struggle to move enough water during a heavy storm. "If your gutters and downspouts are too small for water coming off your roof, adding more downspouts or moving to a larger system entirely is your best option," recommended Davis.
Downspout Replacement or New Installation?
Replacing a downspout is a manageable project for experienced DIYers, but adding a new downspout to a gutter system is more involved. Adding new sections to improve water handling requires creating a new outlet in the gutter and making sure the water has a clear path to drain away from the house—all things you’ll want to think through before you start tearing anything apart. The new connections need to slope properly, be large enough to handle the expected runoff volume, and of course, they can’t be leaky.
Whether you’re replacing or installing a new section, keep these tips in mind:
- Measure before buying materials. Check the distance from the gutter to the ground and plan for any elbows or extensions needed to route the water.
- Match the size to your existing gutter system. A downspout that’s too small might not be able to handle the amount of water coming off your roof.
- Choose the location carefully. If you’re adding a new downspout, look at where water naturally collects and where the gutter is most likely to overflow.
- Plan the path from top to bottom. Your downspouts might need elbows to work around corners, trim, or other features on the house.
- Measure twice, cut once. If you’re adding a new downspout rather than replacing an existing one, cutting a new outlet into the gutter is the part of the project that requires the most planning. The opening needs to be placed correctly, securely connected to the outlet, and positioned so water can flow freely into the downspout.
- Secure every connection. Loose joints can allow water to leak down the side of the house instead of flowing through the system.
- Fasten the downspout securely to the wall. Straps or fasteners help keep the downspout in place during heavy rain and strong winds.
- Think about where the water goes next. Installation isn't finished when the downspout reaches the ground. Add an extension or drainage solution that carries water safely away from the foundation.
How Far Should Downspouts Carry Water Away From the House?
A downspout that ends next to the foundation can send a surprising amount of water into the same area during a storm. The area where it pools becomes saturated, leading to erosion and water problems around the home.
"An often-missed point is that downspout extension distances matter more than people realize,” shares Davis. “Downspout extensions need to carry water at least 10 feet from the house, whether installed below ground or on the surface. To really protect your home’s foundation, an underground downspout extension that extends water out more than 10 feet from the foundation is the best long-term option.”
We couldn’t agree more with this—investing in underground drainage was one of the best things we did for our home.
Surface extensions are an easier solution (and easier to clean) but some homeowners don’t like the look of the protruding gutter extenders, or struggle with how to direct the water without it flowing back towards the house.
Whether you’re burying the extenders or running them from an elbow at the bottom of your downspout, don’t minimize the slope. The slope of any extender needs to be considerable to prevent backflow during heavy rainstorms; we aimed for 1” over every four feet to make sure the water had a clear exit.
Also, before you choose where to send the water, look at the slope of your yard and nearby surfaces. Don't direct water toward a neighbor's property, a walkway or your driveway. You also don’t want to let it pool in another low area. Let it settle into an area with good drainage, whether it’s a stone bed, a rain garden filled with plants that thrive in moisture, or deep into an area of your lawn that never turns into a pond during bad weather.
Common Downspout Repairs You Shouldn't Ignore
Downspouts can develop small problems that are relatively easy to fix. Ignoring them can allow water to reach areas where it can cause more expensive damage.
The team at Groundworks recommends treating the entire gutter system as one connected system: "I always tell homeowners to clean gutters at least twice a year, with a heavier cleanout in late fall to account for early fall leaf shedding and again in spring before the rain picks up,” shares Davis. With the cleanout, perform an inspection. "The biggest signs to check for are leaks, rust and sagging gutters. If a section is rusty, this is not cosmetic; it means your gutters are losing structural integrity and will only get worse from there."
During that bi-annual inspection, look for:
- Clogs caused by leaves and other debris
- Leaks around seams and joints
- Loose fasteners or straps
- Bent or crushed sections
- Rust
- Sagging gutters
- Disconnected extensions
Why Fall Maintenance Can Prevent Bigger Problems
With fall approaching, start thinking about gutter and downspout inspections. When leaves and other debris clog gutters and downspouts, water can back up and overflow, pooling around your foundation where it causes problems.
"Debris can trap water in the gutters and prevent it from draining to the ground,” reminds Davis. “Freezing temperatures make problems worse when water is trapped in the gutters. Snow and ice can build up and allow ice dams to form, trapping water at the roofline and allowing it to potentially seep into your soffits and attic. Checking for and repairing clogs, leaks, loose fasteners, or gutter sag now will be a lot less invasive and expensive than dealing with foundation repairs or wood rot once winter sets in."
FAQ
Can I install a downspout myself?
Replacing an existing downspout can be a reasonable DIY project if you're comfortable working on a ladder and using basic tools. Adding a new downspout requires cutting an outlet into the gutter and planning where the water will drain, so some homeowners prefer professional installation.
Why does my gutter overflow when it isn't clogged?
Your home’s gutter system might not have enough downspouts or could be too small for the amount of water coming off the roof. If the gutters are clean and securely attached but still overflow during heavy rain, evaluate the size and layout of the system.
Should I replace a rusty downspout or repair it?
Small areas of surface damage could be repaired, but any rust is going to weaken the material. If the metal is corroded, develops holes, or is becoming structurally weak, make a plan to replace it ASAP.
