What to Know About Hydrostatic Pressure in Basements

June 8, 2023

Basement floor seepage or “groundwater” is caused by hydrostatic pressure. It occurs when water accumulates under the home raising the water table,  putting upward pressure on the basement floor. Floor seepage will typically show itself seeping through the cove joint of a basement or crawlspace. The cove joint is  where the concrete basement floor meets the vertical foundation wall. This pressure can lead to a range of problems, including floor cracks and on rare occasions even structural damage. In this blog post, we will explore the causes and methods of repair for seepage due to hydrostatic pressure.

Causes of Basement Floor Hydrostatic Pressure

The primary cause of basement floor hydrostatic pressure is a build up of ground water underneath the foundation of a building. This excess water build-up will run down the foundation wall underneath the home until it hits clay soil. Heavy rainfall, snow melt, and spring thaws increase the amount of water around and under a home. Other factors such as poor yard drainage, and underground springs also contribute to water underneath your home.

Consequences of Basement & Crawlspace Floor Seepage

The consequences of basement groundwater seepage can be worth a concern. In addition to possible structural damage by structural sinking or horizontal pressure against a foundation wall, it can also lead to mold growth. Additionally, water damage can ruin personal belongings stored in the basement, such as furniture, electronics, and personal valuables.

Preventing and Repairing Basement & Crawlspace Ground Seepage

WHAT CAN YOU DO?

There are a few basics homeowners should focus on to help reduce or alleviate the possibility of ground seepage.  Always make sure gutters are clean and downspouts are extended a minimum of 6 feet from the foundation wall. These two practices ensure unnecessary water is being kept away from the foundation wall. 

Another focus for homeowners is the soil grading of their lot. Positive soil grading is important as a slope away from the home will keep water away from the foundation. If you have negative soil grading you should consider the installation of a French drain. A French drain is a shallow trench along the wall, pitched to redirect water away from a home.

How We Prevent Groundwater Penetration

If the basics still do not solve basement ground seepage, a drain tile system may be neccesary. A drain tile system is an interior drainage system that captures groundwater and routes it to an 18×22 sump pit basin. Inside the fiberglass basin, we install a ½ horsepower cast iron sump pump to eject the water outside the home. 

DRAIN TILE INSTALLATION:

1. Breakout concrete along exterior walls approximately 8-10 inches from the foundation wall.
2. Next, a 9-inch deep trench is created by digging out the existing clay and dirt.
3. After trenching, an 18×22 sump pit basin containing a ½ hp sump pump is installed. The pump connects to a 1 ½ inch pvc discharge line that extends outside the home to eject groundwater.
4. After the trench is sloped towards the sump pit basin a 4-inch perforated drain tile protected by a filter sock is installed. This drain tile is connected to the sump pit basin.
5. The Drain tile is then surrounded by pea gravel to keep any debris from entering the drain tile possibly causing a clog.
6. A drainage board is an optional feature typically only used on cinderblock foundations to capture any seepage coming through the wall.
7. Next, a new 3.5 – 4 inch concrete slab is poured on top of the trench then will be smoothed out with a hand-troweled finish.

We have many customers that claim the drain tile system is a life-changing addition to their homes. If you pay for a home with a basement or crawlspace you should be able to use it however you would like. Our drain tile systems also carry a lifetime, unlimited transferable warranty. Having a good warranty is key when putting your house on the market giving the possible buyer peace of mind. Contact us today to reach the best in the business.