You can avoid or solve most basement seepage problems by following these simple corrective steps, which are listed in order of priority.
- Keep gutters and downspouts clean and direct them away from the basement. Downspouts must be routed to a storm sewer or at least 6 feet away from the foundation to an area where the water flows away naturally.
- Grade soft surfaces. All surface water must flow away from foundation walls. Soil should pitch away from the basement, dropping 6 inches every 6 feet. The soil under any bark or stone mulch around your home must pitch away (ideally, any plastic under the mulch will pitch away too). Check under decks and porches. During a heavy rain, walk around your home to check for pooling water. No water should pool around or flow toward your basement walls.
- Grade hard surfaces. All concrete and asphalt surfaces must pitch away from the basement. Watch slab concrete surfaces beneath decks. Check all stoops, drives, and walks.
- Grade the soil around window wells to direct water away. Seal the window well tightly to the foundation, and keep the inside of the well clean. The inside of the window should have a base of 6″ gravel–not mud. Also, the window well should either have its own drain or should into the exterior drain tile system through the gravel base.
- Check the palmer valve. This check valve must swing free of improper materials easily broken by frost. Also, many open easily to drain water from the drain tile system. If it is stuck closed, water may back up in your basement, and eventually the drain tiles will become plugged with debris. Use a wire to hook the bottom of this round flap valve; it should swing upward on a hinge at the top of the disc. If the valve is stuck, free it with penetrating oil and a pry bar.
- Check the sump pump. The float must easily move up and down to activate the pump. If the float sticks, you will have a flood. Make sure that the pump is secure and will not allow the float to stick to the sides of the crock or the cover. Lift the float to check that the pump will remove water from the crock; the pump should switch on when the float is 8 to 12 inches from the top of the crock. If the pump allows higher water levels than this, seepage near the floor may occur. Replace a sump pump that is old and worn. If your pump runs often, have a spare sump pump handy.
- Look for gaps and cracks in joints. These can allow water to seep next to the basement. The gaps can be filled with a backer rod and concrete joint filler.
- Check for cracks in poured concrete walls or block walls. These should be evaluated and patched by a professional.
- Check for problems with underground storm drain lines. If damp spots and seepage appear near a sump pump or downspout storm sewer line, the problem may be a broken or plugged underground line. You can test this line by running water into the pipe with a hose and watching for seepage in the basement. You can also temporarily abandon the underground line and route the sump pump or downspout to the surface, well away from your home. If seepage no longer appears in the basement, you’ll know the problem is a broken drain line.
- Investigate underground water supply lines. If seepage occurs near the water main into your home, suspect a broken underground water line.
- Investigate all homeowner-installed underground drain lines. Often they are unable to withstand freezing because they are installed too near the surface and/or they’re made of improper materials easily broken by frost. Also, many such lines can’t effectively carry water away from the foundation because they have poor pitch or are undersized. Temporarily abandon these lines to test them. If you see water bubbling up from connections to these lines, you have a problem.
- Watch for roots in the sump pump crock. Roots inside the crock mean there are roots in the bleeders and in the outside drain tiles. An expert should evaluate this problem.
Bob Beisbier, owner of BK Home Inspections, is a Certified Master Home Inspector who has been providing professional and thorough home inspections in southeast Wisconsin for over 12 years. Bob is Infrared certified, DILHR Certified, and provides Home Energy Tune-ups, Environmental Data Reports, Pre-sale Home Inspections and Pre-offer Home Inspections.