Repairing Leaks in Concrete and Masonry Walls

Cracks or breaks in concrete or masonry basement walls can turn into active water leaks as the soil around your foundation becomes saturated with rain or irrigation water. Repairing leaks and preventing costly damage requires a little preparation to the repair area and QUIKRETE Hydraulic Water-Stop Cement. QUIKRETE Hydraulic Water-Stop Cement is a very rapid setting repair material made with special fast-setting hydraulic cements.

Hydraulic Water-Stop can permanently stop an active water leak in as little as three to five minutes. However, proper crack preparation is essential to achieving a successful repair. Using a masonry chisel and hammer, widen the crack to a minimum width of about three quarter inch and then remove all loose material. Make sure the edges of the crack are cut squarely. Hydraulic water stop expands as it hardens, locking itself into place, so it’s important not to create v-shaped edges.

Mix hydraulic water stop at about four to four and a half parts water stop cement to one part clean water. Always wear safety glasses and waterproof gloves when working with hydraulic water stop or any other cement based product. Use a margin trowel to thoroughly mix the material to a heavy putty consistency. Make sure that the mix is uniform and lump free. If the mix is too wet, add additional water stop cement and mix thoroughly.

If the mix is to dry add small amounts of water sparingly and quickly. Hydraulic water stop sets extremely fast, so do not mix any more material that can be used in two to three minutes. Once a putty consistency is achieved, take a handful of water stop in your gloved hand and begin to work the material into a ball. You will feel the water stop cement begin to get warm in your hand. Now, press the water stop cement into the crack, using heavy pressure and hold in place for several seconds.

After the material becomes thumbprint hard, use a margin trowel to trim the patch to match the contour of the surrounding surface. The water stopped repair can be painted after seven days, with a water-based latex paint. Hydraulic Water-Stop can also be used to repair leaks in swimming pools and fountains and the material can even set under water.

Project Instructions

When working with cement-based products, always wear eye protection and waterproof gloves.

Step 1
Using a masonry chisel, enlarge the crack to a minimum ¾-inch width and then remove all loose material.

Step 2
Squarely cut or undercut the edges of the crack. It is important not to create “v” shaped edges as the Hydraulic Water-Stop expands as it hardens.

Step 3
Mix Hydraulic Water-Stop by adding about 4 to 4 1/2 parts Water-Stop cement to 1 part clean water.

Step 4
Use a margin trowel to thoroughly mix the material to a heavy putty consistency, making sure that the mix is uniform and lump free. If the mix is too wet, add additional Water-Stop cement and mix thoroughly; if the mix is too dry, add small amounts of water sparingly.

NOTE: Hydraulic Water-Stop sets extremely fast, so do not mix any more material than can be used in 2-3 minutes.

Step 5
Once a putty consistency is achieved, take a handful of Water-Stop in your gloved hand and begin to work the material into a ball.

Step 6
Press the Water-Stop cement into the crack using heavy pressure and hold in place for several seconds.

Step 7
After the material has become “thumbprint” hard, use a margin trowel to trim the patch to match the contour of the surrounding surface.

Step 8
The Water-Stop repair can be painted after 7 days with a water-based latex paint.