Leaks
Basement Leaks Only After Heavy Rain? Here's Why
Updated · Holdfast editorial · 2 min read
What should you check outside first?
Common causes:
- Clogged or overflowing gutters
- Downspouts discharging near the wall
- Soil sloping toward the house
- Window wells filling with water
What clues can you find inside?
Water at one wall or corner usually lines up with a downspout or low grading outside.
When is it more than surface water?
If water appears across the floor or days after rain, groundwater may be involved and drainage may be needed.
Where does the water come from?
A leak that only appears in heavy rain usually has an outside cause close to the house:
- Downspouts dumping at the foundation, or underground downspout lines that are clogged or broken
- Soil sloping toward the house instead of away
- Window wells filling with water
- Gutters overflowing at one corner
- A driveway or patio draining toward the wall
Which cheap fixes should come first?
Extend downspouts, regrade low spots and clear window well drains, then watch the next heavy rain. If the leaks stop, you've avoided an unnecessary waterproofing system. If water still comes in at the floor-wall joint, pressure is building under the floor and interior drainage to a sump is the usual fix.
Call a professional if
- Downspouts emptying at the foundation
- Soil sloping toward the house
- Puddles near walls after rain
- Soggy yard spots
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About yard drainage, grading & downspoutsWhat else do people ask about this?
Can gutter fixes stop basement leaks?
Often, when water only appears after heavy rain.
How far should soil slope away?
Ideally several inches over the first ten feet.
Where can I verify this information about your home?
- 1FEMA: Flood Map Service CenterCheck whether a property in your home is in a mapped flood zone before finishing a basement.
- 2U.S. Environmental Protection Agency: RadonWhy basements in your home should be tested for radon, and how sealed sumps fit with mitigation.
- 3USDA Natural Resources Conservation Service: Web Soil SurveyLook up soil drainage class and shrink-swell potential for any lot in your home.
- 4NOAA National Centers for Environmental Information: U.S. Climate NormalsAverage precipitation, snowfall and temperatures for weather stations near your home.
- 5Federal Trade Commission: Hiring a ContractorWhat to check before hiring: licensing, insurance, written estimates and payment terms.
Every home differs; editorial standards.