Mortar Joints: A Common Cause of Seepage

Howard Shachter, vice president of U.S. Waterproofing, explains what exactly a mortar joint is and why is can be a common cause of basement seepage.

A mortar joint is the grout-sealed area between the brick, or mortar, of your house and the concrete foundation that is buried below the earth. The grout sealing the joints, as well as the brick above it, is water permeable, which means that water can slowly penetrate in the right conditions, such as when there is high water pressure within the earth. For this reason, mortar joints are a common cause of seepage problems in many basements.

The problem usually starts with landscaping! That’s right; it is important what grade, that is the slope and height of your land, is at. If the earth that is up against your house reaches up to your brick and is wet, the water pressure can cause water to seep through the mortar, over the top of your foundation and down the walls into your basement.

Now, this problem is relatively easy to fix. We have a special waterproof membrane that we apply to the mortar joint that seals it tight. If the soil is much too high, you might have to get your land regraded, but this is not that common an issue. Until we found this membrane material about 15 years ago, there was nothing we could do about this problem. Now we simply dig up along the side of the house and apply the sealant. We usually advice customers to do the entire wall, rather than a small part as once we are doing the job anyway, it costs very little to just do the entire wall and get it over with.

Sometimes, there are planter boxes on the outside of homes, usually made of brick or concrete, and those are built right against the house. These contain water which collects and may even have sprinkler systems built within. To repair those, we have to empty out the planter box and apply the membrane to the brick and put it all back together again.

So mind your grades, protect your mortar joints, and ensure you have a waterproof basement today.