The short answer
Find the Leak Source
Before sealing anything, identify where the water enters. Check the window frame, the sill, and the seam where the metal or plastic well meets the foundation wall. Look for cracks in the concrete or gaps in the caulk. Water often travels along the outside of the well and seeps through small openings.
Inspect the well drain at the bottom. If it is clogged with leaves or soil, water can pool and rise above the window sill. Clear the drain and test it with a hose. If the leak appears only after heavy rain, the source is likely outside, not the window itself.
- Clean out leaves, dirt, and debris from the well
- Test the drain with water to confirm it flows freely
- Inspect the window frame for rot or warping
- Check the caulk around the window and well edges
- Look for cracks in the foundation near the well
Prepare the Surface
Once you find the leak, prepare the area for sealing. Remove old, cracked caulk and loose mortar using a putty knife or wire brush. Clean the surface with a mild detergent and water, then let it dry completely. Any moisture left behind will prevent the sealant from bonding.
For concrete surfaces, use a masonry cleaner or a stiff brush to remove efflorescence and dirt. If the surface is damp, wait for a dry day to apply sealant. In humid climates, choose a product intended for wet conditions and follow the label instructions for application temperature.
Apply the Right Sealant
Use exterior-grade polyurethane caulk or a silicone-based sealant for gaps around the window frame. For cracks in the concrete foundation, hydraulic cement works well because it expands slightly and sets hard. Apply the sealant in a continuous bead, pressing it into the gap with a caulking tool or your finger.
For larger gaps, fill the space with a backer rod before applying caulk. This reduces the amount of sealant needed and prevents it from sagging. Smooth the surface with a wet finger or tool. Allow the sealant to cure for the time stated on the package, usually 24 hours, before exposing it to water.
Improve Drainage Around the Well
Sealing the window well alone may not stop the leak if water collects around the foundation. Ensure the ground slopes away from the house so rainwater runs off. Extend downspouts away from the foundation and consider installing a French drain if the soil stays soggy.
A window well cover can keep rain and debris out, reducing the amount of water that enters the well. Covers are especially useful in areas with heavy storms. If you live in a coastal region with frequent heavy rain, a cover can be a simple addition. Check that the cover fits securely and does not block the window's emergency exit.
When to Call the Pros
If the leak continues after sealing, or if you find soaked drywall, stained walls, or mold near the window, the problem may be more serious. Water can travel through the foundation and affect areas you cannot see. A water damage inspection can reveal hidden moisture and help you understand the full scope.
Local water damage pros can measure moisture levels, identify the source, and recommend repairs. They can also handle cleanup if the leak has already caused damage. If the window well is rusted or the foundation has large cracks, you may need a contractor to rebuild the well or repair the foundation. Acting quickly prevents further damage.
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Call Now (386) 272-5697Frequently asked questions
Can I seal a window well from the inside?
Sealing from the inside can stop water from entering the room, but it does not fix the source. Water will still collect in the well and may cause damage over time. It is better to seal the exterior where the water enters, using caulk or hydraulic cement, and improve drainage outside.
What is the right sealant for basement window wells?
For gaps around the window frame, use exterior-grade polyurethane or silicone caulk. For cracks in concrete, hydraulic cement is a good choice because it expands and bonds well. Always choose a product intended for outdoor use and follow the manufacturer's instructions for proper results.
How often should I check my window well for leaks?
Check your window well at least twice a year, especially before the rainy season and after heavy storms. Look for cracks in the caulk, debris in the drain, and signs of water on the walls. Regular maintenance can catch small issues before they become major leaks.