Can Downspouts Cause Water Damage to my Home?

Gutters get a lot of attention, and rightly so. They catch the water that runs off your roof and channels it away. But where does the water go from there? Cue downspouts, the gutter’s underappreciated vertical cousin. In wet climates like ours here in the Portland area, downspouts serve an especially useful purpose. However, incorrectly installed downspouts can cause a serious risk of water damage to your home.

At Lamont Bros., our team of remodeling experts has spent decades working on homes across the Portland area. We’ve seen firsthand the importance of having an effective gutter system. Though an intrinsic part of rainwater drainage, downspouts are often installed without thought for the home’s foundation, which can cause water damage and leaks. The result is often disastrous for the home.

In this article, we’ll discuss the importance of proper downspout placement and design. Once you reach the end, you should have a better understanding of how downspouts work. With that information, you’ll be able to more effectively prevent water damage to your home from your downspouts. Topics we’ll cover include:

What are downspouts and what does it do?

Downspouts are vertical pipes that work with your home’s gutter system. Rainwater drainage is extremely important to the health of your home. Water causes damage and rot if allowed to sit long enough on the side of your home. If not directed properly, it can also erode the ground beneath the foundation. Gutter systems prevent this by channeling rainwater away from the home.

What do downspouts do?

The downspout is an important part of this process. Without downspouts, water would simply cascade out of your gutters and splash on the ground, flowing in whatever direction gravity takes it. If that direction is towards the home, that could be a serious problem. 

The downspout’s job is to keep the water contained as it descends and use the gravitational force of the fall to direct the water out and away from the home. In some homes, the downspout feeds directly into a drainage pipe that leads to the stormwater drain. For other homes, the downspouts pour water onto the ground. With these types of downspouts, it is especially important to make sure that the water flows away from the home to prevent water damage.

When installed correctly, downspouts greatly reduces the risk of water damage to the home. This can come in several forms. The most common is foundation leakage, where water collects near the foundation and over time seeps through cracks in the foundation wall. Standing water in your crawl space can be a serious health hazard and can rot the structural members of your home.

It’s also common for improperly installed downspouts to erode the earth around your foundation. If this happens enough, it can compromise your home’s structural integrity by destabilizing the ground beneath it.

What do downspouts look like?

Some downspouts may look different or have different features. Most downspouts in the Pacific Northwest are enclosed pipes made of aluminum or vinyl. Another common option is a “rain chain,” which is a chain that channels water in much the same way as a traditional downspout. Designer downspouts with open faces offer a more visually appealing option.

What are some important design principles of downspouts?

To work correctly, a gutter system must follow a specific set of guidelines. Some of these guidelines directly affect the placement and design of your downspouts. Here are a few of them.

Equal drainage of roof surface area

Every downspout is responsible for draining a certain amount of the roof’s surface area. If any one downspout has to drain significantly more surface area of the roof, that means a lot more water will concentrate in one drainage spot. This could increase the risk of standing and accelerate erosion, both of which may cause damage to your home if not addressed. 

To ensure that the downspouts can handle the total volume of drainage from the roof, it’s important to make sure that the surface area of the roof is equally divided among the downspouts. So, if you have 4 downspouts, 25% of the roof’s surface area should drain to each one to avoid overloading any one downspout.

One downspout every 30-40 feet

It’s also important to consider the number of individual roof faces on your home, as well. Every flat surface on your roof should have its own gutter and enough downspouts to drain the amount of rainwater it receives. A good rule of thumb is to have one downspout every 30-40 feet. Typically, this means one at each lower corner of every roof face.

A downspout channels water from the gutter to the ground.

All downspouts should drain at least 10 feet from the home

Once the water reaches the ground, it needs to be able to flow at least 10 feet away from the home to prevent water damage. When assessing the drainage from your downspouts, carefully consider the topography of the property. It’s possible that in some areas, the water from the downspouts will flow right back towards the home. To prevent this, the gutter system should direct as much rainwater as possible toward the lowest side of the property. In other cases, it may be best to connect the gutters to a municipal storm drain.

What are some best practices when working with downspouts?

When it comes to preventing rainwater from damaging your home, there are some simple steps that you as a homeowner can take. Here are a few of the most effective.

Upgrade downspouts on older homes

Many older homes built in the early to mid-20th century have significantly smaller downspouts. As a result, the size of these drainage pipes can restrict the flow of water and back up your gutter system. The easiest solution is to upgrade these old downspouts to larger, more contemporary ones. While you’re at it, check to make sure the downspouts are draining properly and in the right direction.

Flood test your storm drain system

If your downspouts feed directly into a storm drain pipe, you should check to make sure that your storm drain system works correctly. When water doesn’t properly drain from your home, you end up with standing water around your foundation. 

Fortunately, there’s an easy way to flood-test the storm drain and make sure it works. Feed a hose into the storm drain and turn it on full blast for 5-10 minutes. If the drain backs up and water rises to the top of the drain, you’ll want to call a professional out as soon as you can. If the water drains with no issue, you’re good to go.

Regularly check your crawl space

If you live in a rainy climate like Portland where rainstorms and wet weather are common, you should be in the habit of regularly checking your crawl space for water.  You can ensure your downspouts are not backing up into your crawl space by checking to see if the crawl space is dry. As long as there’s no moisture under your home, you should be safe from major leakage.

Know the signs of a clogged gutter system

A gutter system only drains properly if water can flow freely from the roof to the drainage system. Any obstructions in the gutters or downspouts can cause the water to drain incorrectly or not at all, which puts your home at risk of water damage. To make sure you catch any issues before they become hazardous to your home, know the signs of a clogged gutter.

Overflowing gutter: If water is flowing out over the edges of your gutter instead of the downspout, that means one of two things. Either your downspout is clogged or your gutters need to be cleaned immediately. Both are urgent and should be a top priority.

Soft soil around drainage pipe: When the soil becomes soft around the drainage pipe at the ground level, that usually means water is pooling around the pipe rather than going into it. This may be a sign of a clogged drainage pipe.

Mud splashing on siding or foundation: If you see mud-splattered along the side of the home or your foundation, that may be from water somehow escaping your gutter system. Fortunately, mud splatter can also help to locate the source of the problem, as well.

Ready to learn more about remodeling your Portland home?

After reading the information above, you should be able to better understand and identify potential risks of water damage with your home’s downspouts. Now, take the next step. To learn more about how the rainy Pacific Northwest affects home remodeling in the Portland area, read our article, “When is the Best Time of Year to Remodel in Portland?

If you have remodeling questions and are ready to start discussing them with a professional, click the button below to get connected with a member of our design team. We’ll help you navigate the challenges of remodeling your home from start to finish.