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Technical Papers

Basement Waterproofing - Hydrostatic Pressure and Basement Leaking

Thursday, February 2nd, 2023 by Aaron Stull

Hydrostatic Pressure and Basement Leaking - Image 1Hydrostatic pressure is a condition that occurs when water accumulates in the soil surrounding a home. If you are reading this, you may suspect that this force is at play with your basement or subterranean space water intrusion issue.  This water can come from various sources such as rain, snow melt, or a high water table. When the water accumulates, it creates pressure that can eventually push through basement walls and floors, causing leaks.

In a typical home, the basement is constructed with a waterproof barrier, such as a membrane or a sealant, to prevent water from penetrating the walls and floor. However, these barriers can deteriorate over time or be damaged by shifting soil, causing leaks to occur.

One main factor that contributes to hydrostatic pressure is the height of the water table. The water table is the level at which water is found in the soil. When the water table is high, it can cause water to accumulate in the soil surrounding a home, leading to increased hydrostatic pressure. Sometimes this is hard for people to imagine, because the water we are talking about is suspended in soils and underground. Another factor that is difficult to understand is soil density. The virgin soils that were not dug up when the structure was built are dense and more difficult for water to move through. The fill soils that were dug up and and put back - even 100-200 years ago - will be far less dense that those that are many thousands years older. Thus this suspended water sits in what is essentially a “bowl” and builds up against the walls analogous to water up the side of a ship.  But since the foundation walls were not designed for this high of a water pressure, they leak.

Another factor that can contribute to hydrostatic pressure is the type of soil surrounding the home. Clay soils are especially susceptible to retaining water and creating hydrostatic pressure. This is because they have a low permeability, which means they are not able to absorb water quickly. As a result, water can accumulate and create increased pressure.

In addition to the height of the water table and the type of soil, other factors that can contribute to hydrostatic pressure include terrain features, changes in the slope of the land surrounding the home, poor grading and drainage, and the presence of underground springs.

When hydrostatic pressure builds up in the soil surrounding a home, it can cause basement leaks in several ways. For example, the pressure can push through cracks or gaps in the walls or floor, causing water to seep into the basement. Additionally, the pressure can cause water to seep through the walls and floor themselves, leading to moisture buildup and mold growth.

The consequences of basement leaks caused by hydrostatic pressure can be significant. Not only can they cause damage to the home and its contents, but they can also create a conducive environment for mold growth, which can pose a health risk to the home’s occupants.

To prevent hydrostatic pressure from causing basement leaks, there are several measures that can be taken. For example, installing an interior waterproofing system or an exterior waterproofing system can help to protect the home from water infiltration. Additionally, improving grading and drainage, and sealing cracks and gaps in the walls and floor can help to reduce the risk of leaks.

In conclusion, hydrostatic pressure is a common cause of basement leaks in homes. By understanding the factors that contribute to this pressure, and taking steps to prevent it from occurring, homeowners can help to protect their homes from the damaging effects of water infiltration and mold growth.

Are you having a basement issue? Click HERE or give us a call at (800) 771-3244.

About the author
Aaron Stull is a second generation foundation repair specialist from the greater Pittsburgh, Pennsylvania area.

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