An incorrectly sealed connecting point between a concrete wall and a concrete floor creates a void. Voids in concrete structures allow water and the deadly gas known as radon to seep into the space. Water seepage damages materials stored in the area, and deadly radon is a health hazard to anyone using or living in the space. Correctly sealing the joint where a wall meets the floor will stop water and radon from seeping into the space.
Attach a diamond-tipped grinding wheel to an angle grinder.
Soak the connecting point between the concrete basement floor and wall with a water sprayer. Allow the water to seep into the concrete for 15 minutes and repeat the process.
Hold the angle grinder at a 45-degree angle to the water soaked seam. Press the angle grinder trigger. Move the grinder along the connection until a 1/2-inch deep groove runs along the entire wall. Turn off the angle grinder. Soak the groove with water from the sprayer. Run the hose of a wet/dry vacuum over the groove to remove excess water from the area. Allow the concrete to dry for 12 to 14 hours.
Place an open tube of urethane sealant in the body of a caulk gun. Set the tip of the caulk tube in the 1/2-inch groove. Squeeze the gun handle to dispense caulk as you move the gun along the groove. Ensure the bead of sealant extends beyond the front of the wall.
Drag a spoon along the bead of sealant to blend it into the surface of the wall and floor. Wipe the spoon on a rag to remove excess sealant as you blend the sealant.