What is Basement Water Seepage?

Waterproofing guru Howard Shachter, vice president of U.S. Waterproofing, tells what basement water seepage is and some common causes and solutions for this problem.

Seepage is small amounts of unwanted water that for various reasons can enter into your basement. Seepage is best defined by comparing it to what it is not, and that is flooding.

Flooding is when feet of water covers the entire basement floor –- a certain huge and major emergency situation that only those who have experienced it can truly know and fear. Flooding is most common in our Chicago area from the sewer system backing up during heavy rainstorms, which as I am sure you can imagine, is just a terrible situation. Water comes up out of floor drains and the toilets and creates a horrible mess. Flooding can also be in other area from rivers overflowing in exceptionally heavy rainfall when they jump their banks - a natural disaster which is awfully hard to prevent.

Seepage, one the other hand, doesn’t usually cover the entire floor and is rather often a small trickle of water that is a nuisance — and certainly a problem if not taken care of. But it is nowhere near the catastrophe that a full-on flood is. Seepage is usually between up to several inches of water covering almost the entire floor or even a tiny amount of water that comes in and can evaporate before anyone even notices it was there. Seepage is controllable. Flooding is usually not. Seepage has various causes, but can always be controlled and fixed.

Some common causes of seepage:

Perhaps the most common cause of seepage is when unwanted water comes in through the cove joint - the joint that connects the floor of the foundation to the wall. This is common as when a house is constructed, a builder first lays footing, then pours the foundation walls and afterward lays the concrete flooring. Because there is a time difference between when the concrete of the floor and walls is cured, the joint between the floor and the wall is essentially a sealed crack that can often wear and start to seep.

Water can also come over the top of the foundation, through the mortar joint, when the land grading is too high. Water will seep through the brick and over the foundation wall and enter where the wall meets the ceiling, the space known as the mortar joint. Mortar and brick are porous, so water can penetrate brick and come right over the foundation and trickle down the wall and collect on the floor.

Other common causes can be leaky window wells or water penetrating the foundation walls. This could be through a crack in the wall itself or in the area around a sewer, water, or electrical pipe if it is not sealed properly. The area around the pipe can often leak when the water pressure gets too high in the ground outside.

Learn how we test for seepage.