The Dos & Don’ts of Waterproofing Basement Walls


Water tends to accumulate in basements since they are below grade. During the rainy season, you may experience flooding in your basement, or the walls of the basement may become moist. Wet basements can lead to paint peeling, mold growth, wood rot, and damaged items.

Basement walls can crack over time, even if builders waterproof them during construction. If the soil outside becomes saturated, water will seep through these cracks. Although basement walls are structurally sound, they can absorb water from the soil and transfer it to their interiors, making them feel damp even when they are dry. Water evaporates from basement walls, making the air in the basement humid. Dehumidifiers can help reduce basement humidity, but waterproofing the walls is the best long-term solution.

Determine Source of Water

Due to concrete’s porous nature and ability to show where the water comes from, you often see wet streaks on it. There can be cracks in the walls, cracks around windows, cracks between mortar joints (on cement block walls), and cracks around pipes, such as a water supply line or a sewer line.

Further investigation is needed if the wall surface is wet. You can test for condensation by placing a square of aluminum foil on the wall with duct tape and drying the area with a rag. After 24 hours, peel off the foil to test the underside. Wet walls indicate a leak from the outside. Basements that are moist probably have other sources of moisture, such as a basement shower – a simple fix that can be accomplished by installing a vent fan in the bathroom to direct steam outside.

Standing Water Repair

The crack in a basement wall can allow water to enter if it is raining, but before you repair the crack, make sure you have removed all the water from the floor. In a flooded basement, there is a greater risk of electrocution or shock. Using an extension cord extending from an upstairs outlet, you can operate the utility pump to remove water from your basement by turning off the power. The water is then discharged via the garden hose. It is possible to inspect, repair, and waterproof basement walls that are not flooded.

Fill Cracks With Cement

Cracks are also common at the bottom of basement walls. A foundation’s footing is poured first, then the walls are poured after the footings harden, which forms a wide flat base made of concrete and steel.

 It is common practice for foundations to be built this way, but it can create “cold joints,” weak spots where cracks may develop from shifting foundations and lateral pressure caused by soil.

Make Drainage Solutions

It is also possible to keep basement walls dry by installing drainage channels beneath the floor. The drain is installed just inside the basement walls, just like the exterior drain tile described above. Then new walls are built around it to hide the original basement walls. This project should cost about $5,000 to complete by a foundation contractor. After the job is finished, you’ll have new, dry walls, and the drain channel will be used to pump any residual water out.