From roof to basement wall
Older east Denver neighborhoods were planted generously, and many Hilltop lots have large shade trees that are decades old. Every fall, and again in spring when seeds and blossoms drop, those trees load gutters with debris. A clogged gutter overflows at its low corner during a storm, pouring a concentrated stream of water onto the same patch of ground beside the foundation, often right above a basement wall or window well.
Short or missing downspout extensions do the same thing in a quieter way. A downspout that ends at the foundation puts nearly all of a roof section's water into the soil within a foot or two of the basement. Front Range soils commonly include clays that swell when wet and shrink when dry, and repeated soaking at one spot can open small gaps along the wall, loosen settled backfill, and push moisture through older concrete.
Trees add a second effect. Roots draw moisture from the soil and can lift sidewalks or patios so they tilt toward the house. Over decades, the ground near the foundation may settle until it slopes inward rather than away, and nobody notices until a finished basement begins to smell.
Outside checks that prevent inside mold
- Clean gutters after the main leaf drop in fall and again in late spring
- Watch the gutters during a heavy rain to see where they overflow
- Extend downspouts several feet from the foundation, or into a drain line that is known to be clear
- Make sure soil, mulch and rock beds slope away from the house rather than toward it
- Look for sidewalks or patios that have settled toward the foundation
- Keep sprinkler heads aimed away from basement walls and window wells
- After storms, check the basement walls on the side of any overflow
Matching outdoor clues to indoor symptoms
- Outdoor clue
- Splash marks or eroded soil below a gutter corner
- Likely indoor symptom
- Damp spot or stain low on the wall below
- First response
- Clear the gutter, add a splash block or extension
- Outdoor clue
- Downspout ending at the foundation
- Likely indoor symptom
- White mineral deposits on the concrete inside
- First response
- Extend the downspout and regrade the area
- Outdoor clue
- Patio tilted toward the house
- Likely indoor symptom
- Seepage along the slab edge on that side
- First response
- Have the patio slope assessed and corrected
- Outdoor clue
- Tree roots heaving soil near the wall
- Likely indoor symptom
- Fine new cracks in the foundation
- First response
- Ask an arborist and a foundation contractor to look together
Common questions
Do gutter guards solve the problem?
They can reduce clogs, but some designs still collect seeds and fine debris. They are not a substitute for checking that water actually reaches the downspouts and leaves the foundation area.
Should I remove a large tree near the house?
Not without advice. Healthy mature trees have value, and removal can change soil moisture too. An arborist can suggest options such as root management or pruning.
General information for Hilltop, not a quote or professional advice. In an emergency, call 911.