Damp Clay Soil Under the Foundation – Should I Worry?

Damp clay soil is bad news for any homeowner. If you don’t act now, you could be staring at serious structural problems that could jeopardize your home’s structural integrity. 

What is Damp Clay? 

Damp clay refers to soil that’s wet or has significant moisture.  

Clay soils tend to swell or expand when they come into contact with water. Soils rich in silt or clay have the greatest swelling potential and the greatest potential for foundation damage. They can cause heave and shift, cracks, and foundation settlement, which is costly to repair. Come summer, this soil will shrink and crack as it loses water, leaving gaps around and below your foundation. 

Why is the Foundation Soil Damp? 

Foundation soils experience wetting and softening under these two conditions: 

Heavy rains: As clay soaks up water from heavy rains or storms, it holds it and becomes soft. This softening makes the soil weak and might cause the foundation to shift. 

Poor drainage: If water pools around your foundation after a downpour or snowmelt, the soil will absorb it and swell. This can lead to cracks in the foundation and bowing walls. 

Be sure to perform structural checks at least once a year, starting from the inside out. Check for potential issues attributed to expansive soils. 

Signs of Damp Clay Soils 

Let's look at red and yellow flags that your home or foundation is experiencing issues relating to expansive clay soils. 

• Basement/foundation wall cracks 
• Soil pulls back from your foundation in summer 
• Sagging or bouncy floors 
• Windows and doors that stick to their frames or rub 
• Doors that self-close or open 
• Gaps around your door, particularly at the top and sides 
• Brick veneer cracks 

Some of these telltale signs could be from other issues, not just the foundation soil. Just to be sure, ask your foundation repair contractor to complete a thorough evaluation and confirm your suspicions. 

Should I Worry about Damp Clay Soil? 

Water and clay soils have a stronger interaction due to the high surface area and the structure of the clay minerals, as well as the polar nature of water molecules. Minerals in clay also tend to influence the soil's behavior and movement. 

Overly wet clay, with a near-mud consistency, loses its ability to hold the weight of your foundation and house. Think of what happens when you trudge on a muddy lawn. Your feet will sink into the mud. So, the same thing will happen to your house if the clay soil under the foundation soaks up water. 

In some areas, expansive soils can exert an uplifting pressure that’s as high as 5,000 psf (pounds per square foot) on the foundation. No foundation can withstand such tremendous pressure and stay intact. 

If this soil moves upward, it can displace your foundation by six to eight inches. Not only does this cause your floor to go out of level, but it can also raise one side of your home. 

Ways to Prevent Wet Clay 

Moisture is the major culprit and your number one nemesis in keeping your foundation dry, healthy, and intact. As a homeowner, you want to make sure you manage the moisture content in the foundation soil. Begin by: 

• Installing gutters and downspouts to move water away from your home’s perimeter. 
• Controlling the watering of plants next to the foundation. 
• Ensuring the condensate line of your A/C discharges away from the foundation. 
• Timing your sprinklers and ensuring the lawn doesn’t get soggy from overwatering. 
• Regrading to a positive slope so water runs off quickly. 
• Planting trees at least 10 feet from your house. 
• Ensuring no neighbor drains onto your property or near the house. 
• Installing waterproofing systems like an interior drainage system and a sump pump. 
• Building strong foundation walls that withstanding the intermittent pressures and loads exerted by damp clay soils. 

Save Your Foundation 

If you suspect that damp clay soil is destabilizing your foundation, contact your local foundation repair experts for a free foundation inspection and quote. These professionals will visit your home, check your foundation for signs of damage, and then recommend an appropriate fix. They also will help you implement effective site drainage so water doesn’t pool around your home.