What Causes Basement Water Seepage?

Groundwater Seepage creates Wet Basements

Basement foundations are built into large holes dug out of primarily clay soils creating “clay bowls”. These “clay bowls” hold water much like a pond holds water. Even after the foundation is back filled, this bowl that the basement was built in will still hold water, because the back filled soil is much less dense than the untouched soil around it. Water percolates through the soil and saturates the area in the bowl, and around the foundation. The result, a wet basement in need of waterproofing.

To prevent water from collecting around the foundation and creating a wet basement or crawl space, the builder installs a drainage system around the perimeter at the base, and seals the walls before back filling. However, sometime after construction, the water brings dissolved soil and sediment into the original drainage system and the drainage system begins to clog. Once this clogging process occurs, water builds around the foundation and creates hydrostatic pressure, forcing the water into the basement through weak points where the wall and floor meet, as well as through cracks in the walls and floor.

Vapor Transmission and Condensation also creates a Wet Basement

Other forms of moisture penetration are much more difficult to see. Vapor Transmission is a process where water molecules move through masonry foundations from the exterior to the interior even in areas where air cannot penetrate!

In the summer season, warm, humid air moves into cooler basement environments. This warm air cools and shrinks. As this happens, the relative humidity rises, and water condenses onto cooler surfaces like cold water pipes, cold air returns, and foundation walls and floors. In the winter, warm air in the basement can condense onto cooler basement walls and floors.

The moisture from groundwater seepage and saturated air is evaporated into the basement environment. The result:

A wet basement that needs waterproofing. Once the amount of moisture entering the basement exceeds the basements ability to evaporate it, signs of moisture begin to accumulate on the walls and floor.

Find out how to identify signs of a wet basement water problem.