Heavy rain in St. Louis can arrive quickly, and a roof sheds a large amount of water in a short window. Where that water lands next to your house determines a good deal about how dry your basement stays and how much moisture your foundation soaks up over time. Downspouts are the easiest part of that system to check, and most fixes are simple enough to handle in an afternoon.
What a downspout is supposed to do
A downspout carries water from the gutter down to the ground. Its job is not finished at the bottom. The water still needs to travel away from the foundation so it does not soak back into the soil right beside the walls. If the outlet dumps water at the base of the house, the water has a short path to the foundation, and that path is where much basement dampness starts.
Signs your downspouts are not working
Walk the outside of the house during or right after a good rain and look for these clues:
- Water standing in a puddle right at the base of a downspout
- A small trench or washed out soil line running along the foundation
- Muddy splash marks or stains on siding near the ground
- Gutters overflowing at the corners or at a joint
- Damp spots on the basement wall or floor close to the outside corner where the downspout sits
Check the gutters first
Before you change anything at ground level, make sure water is actually reaching the downspouts. Work through these steps in order:
- Clear leaves, seed pods, and grit from the gutters and from the top of each downspout.
- Look for sagging sections, separated seams, and rust holes where water can leak out before it reaches the outlet.
- Confirm each downspout is fully connected at the top and at the elbow near the bottom. A joint that has slipped apart sends water straight down the wall.
- Run a garden hose slowly into the gutter and watch where the water exits. This is a simple way to find leaks and blockages without waiting for rain.
Where the water should go
Water should leave the downspout and travel across the yard, toward a lower area, a storm drain, or the street. The ground next to the house should slope away from the foundation so surface water flows outward. Many St. Louis yards have clay soil, which drains slowly and tends to hold water close to the house. That makes the outlet location even more important, because water that sits near the foundation has time to seep into the soil and press against the walls.
Extension options
A downspout extension moves the outlet farther from the house. Common options include:
- Rigid extensions that stay in one place, useful where mowing is not a concern
- Flexible extensions that can be shifted for mowing, but may need to be secured so they do not collapse or kink
- Buried drain lines that carry water underground to a discharge point well away from the house
- Splash blocks, which only move water a short distance and work best when the ground slopes away beneath them
Whatever you choose, the water should end up far enough from the foundation that it does not come back. If you cannot tell whether it does, follow the flow during a rain and watch where it ends up.
Common mistakes to avoid
- Pointing the outlet toward a neighbor's yard or foundation
- Discharging water into a low spot where it pools and backs up toward the house
- Burying the end of an extension in a flower bed that holds water
- Letting the extension tip back toward the wall
- Pulling the extension loose after mowing and not reconnecting it
- Routing the outlet into a window well, where water and debris collect against the glass and the wall
Winter considerations
In colder spells, water leaving a downspout can freeze at the outlet and build into a patch of ice. Keep the discharge away from walkways and steps where it could freeze into a slippery surface. Clear any ice you find at the outlet so meltwater can keep moving away from the foundation.
Keep an eye on the inside
After you make changes, watch the basement and crawl space through the next few rains. Take photos of the walls and floor before you begin so you can compare later. If you notice new damp areas, note where they appear and which downspout is nearest. That detail helps narrow down the cause.
When to get a second opinion
If water still pools against the foundation after you have cleaned the gutters, connected the downspouts, extended the outlets, and checked the grade, it may be time for a local contractor who works with St. Louis soils and drainage to look at the site. Bring your notes and photos from the rain checks. Ask them to explain what they found and why before you agree to any work.