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moldy basement water problems

Clay Bowl Effect

The clay bowl effect causes water to buildup in the soil and exerts pressure on the foundation walls. Learn what you can do to protect your home.

Loose soil around your home’s perimeter may not seem like much of a problem during construction until the rains start falling. That’s when foundation problems start. The foundation starts leaking and water infiltrates the basement. 

While many things can instigate these problems, the clay bowl effect is a common culprit. Here, we will explain this concept and show you how it affects your home. 

What Is the Clay Bowl Effect? 

The clay bowl effect is a natural consequence of digging out soils when constructing a foundation and backfilling it with the same soil. During the initial stages of constructing a house, the builders excavate soil from the ground to create space for your home and its basement. 

The contractors dig a hole that is a little bigger than the space your home will occupy to allow for proper construction. After building the foundation floor and walls, they use the soil that was excavated to fill in the gaps between your foundation walls and the existing earth around the outer edge of the foundation. This soil is known as the backfill. Since this is disturbed soil, it is no longer as dense or tightly packed as the undisturbed soil nearby. No matter how hard the contractor packs the soil, it remains loose and fluffy. 

What does this mean? Since the backfill is both fluffier and more pervious than the compressed, hard-packed soil around it, the soil will create a “clay bowl” around your house. This clay bowl will form an artificial water table that will collect water. 

moldy basement water problems

Signs that you are suffering from the clay bow effect include: 

  • Existing cracks in your foundation leak water 
  • Higher relative humidity in the basement than the rest of your home 
  • Elevated radon gas levels and cracks in your foundation 
  • Persistent mold problems 
  • Several dark patches on the basement walls or floor 

Should You Worry About the Clay Bowl Effect? 

The clay bowl effect is a leading cause of basement leaks, water damage, mold, and mildew growth among other issues. This happens when water from rain, snowmelt, and leaky gutters pools near your foundation, saturating the soil surrounding it. As the water in the soil fills up, it causes the soil to expand and the water’s weight to press against your foundation walls. This is known as hydrostatic pressure. 

Seeking relief, water will work its way into your basement through paths of least resistance like the openings around pipes, concrete cracks in the wall, basement windows directly through the porous concrete, or the foundation wall-floor joint. This water often seeps in through cracks, porous basement walls, and joints between the walls and the floors. Other effects of the clay bowl effect on your home include: 

  • Cracks in your foundation walls: The same pressure weakens joints in your foundation walls and widens cracks. 
  • Bowing foundation walls: Since back-filled soil is looser, it moves more freely exerting additional stress on your foundation walls. The constant pressure due to the clay bowl effect can cause your walls to bow and lose their structural effect. 
  • Radon gas buildup in the basement: The clay bowl effect also increases the levels of radon gas in your basement. As water saturates the soil under your foundation, it traps radon gas, which leaks into your basement through cracks. 

Possible Solutions 

There are many ways to resolve the clay bowl effect, and these include: 

Interior Drainage System 

Installing a full perimeter drainage system along the interior footer of your foundation and in the basement is an effective deterrent against this problem. This drainage system collects all the water that infiltrates the basement and directs it to the sump pump. 

Wall Anchors 

Made from high-grade galvanized steel, wall anchors stabilize the foundation and hold the walls in place, stopping further bowing. They are usually embedded into the soil near the foundation walls. 

Professional Foundation Waterproofing 

Waterproofing the foundation is another effective solution. It prevents outside water from seeping into your home and damaging your wooden supports and soiling your possessions. 

At JES Foundation Repair, we customize all our basement waterproofing and foundation repair solutions to cater to the problem at hand. From lining your walls with a vapor barrier and installing sump pumps to protecting your walls with carbon fiber or wall anchors, we will work with you to create a reasonable, yet lasting solution that best meets your needs. Contact us today to schedule a free inspection and receive a no-obligation quote.

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