Window wells are the small concrete or metal pits that sit outside basement windows. They let light and air reach a below-grade room, and on many older St. Louis homes they also collect rain, leaves, soil and melting snow. When a well fills with water, that water can find its way through a cracked seam, under a poorly sealed frame, or along the wall into the basement. Checking the wells takes only a few minutes, but many homeowners skip it until a damp spot shows up on the wall below the window.
Why window wells collect water
Water runs toward the lowest point. If the ground around a window well slopes toward it, or if a downspout empties nearby, the pit becomes a catch basin. Leaves and mulch wash in and block any drain at the bottom. During a St. Louis spring, when heavy storms follow a wet winter, a well can fill faster than the surrounding soil can absorb the water.
What to check after a heavy rain
Wait until the rain has stopped and the ground has had some time to drain, then look into each window well with a flashlight. Note the following:
- Standing water, or a line on the wall showing that water has risen higher than it is now
- Leaves, gravel, mulch or soil packed against the bottom of the well
- Cracks or gaps where the well wall meets the foundation
- Rust, bulging or loose fasteners on a metal well
- Whether a drain at the bottom, if one exists, is clear and running
Telling water apart from condensation
Water that came through a window well usually shows up low on the wall beside the window, on the sill, or on the floor under the frame. Moisture on the glass and frame during humid weather is a different problem. Condensation forms on cool surfaces even when no rain has fallen, and it tends to appear on the inside of the window during muggy stretches of summer or on cold mornings in winter.
A simple test helps separate the two. Tape a small square of plastic sheeting to the wall or sill, sealing all four edges. Check it after a day or two. Moisture on the room side of the plastic points to humid indoor air. Moisture or staining on the wall under the plastic points to water moving through the masonry or in from the soil outside.
Simple fixes a homeowner can do
- Clear leaves and debris from the well by hand, wearing gloves
- Redirect downspouts so they discharge away from the well and the foundation
- Check that the soil around the well slopes away from the house
- Clean out any drain at the bottom so water can leave the pit
- Seal visible cracks in the well wall or at the frame with an exterior sealant made for masonry, and follow the label directions
Covers and egress wells
A cover keeps leaves and rain out of the well, but it has to allow air and light in and must not trap water. Many St. Louis homes have covers installed decades ago that may be cracked or warped. A cover should lift easily from inside when an emergency exit is needed. If a bedroom has an egress window, keep the well clear enough that the window opens fully and any steps or ladder are not blocked. Requirements for egress and for any change to a well are set by the local building authority, so check with the city or county before altering one.
When to call for help
Bring in a qualified contractor or foundation specialist if water keeps appearing after cleaning and regrading, if the wall shows cracks wider than a hairline, or if the well wall is pulling away from the house. Ask for a written explanation of what was found and why a particular fix is recommended. Compare more than one written estimate before agreeing to work. Keep notes on rain dates and photos of the wells, which help anyone who looks at the problem later.
Keep a simple routine
Check each window well in late winter and again in early fall, and after any heavy storm. Keep the drain clear, the soil graded away from the house, and the cover in good shape. A few minutes of attention each season helps keep a St. Louis basement dry and gives you an early warning if something has changed.