How the clay bowl effect begins

Moisture is an essential element for soil: it is a lubricant that traps air and allows soil particles to slide past each other. Too much moisture and the ground becomes muddy and unable to support the weight. Too little moisture and the soil breaks down into its individual particles and blows them away.

Dry soil also decreases plant root depth because plants spread shallow roots in an attempt to absorb as much moisture as possible. This means that our gardens are more delicate, our trees begin to wither and provide less shade, the earth around our houses begins to blow, and many of our plants produce less. All of these factors make our yards and homes feel warmer and our allergies strike more often. We also started noticing burnt patches on our lawns and brittle leaves on our plants. In an effort to counteract these problems, we watered more. For some reason this doesn’t seem to help.

That’s because most of us are also battling a layer of hardened clay under the grass, which is literally siphoning water into the nearest permeable soil. Unfortunately, the end result can be that the water intended for your lawn is forced into the ground below your foundation; this is called the “clay bowl effect”. Here’s how it works: houses are built by digging or excavating a hole where the foundation will go. Naturally, this hole has to be wider than our foundation because people and machines also need room to work. Once the base is poured and dried, the filling is done. In other words, the hole is filled until it is level with the virgin soil surrounding the construction site. This fill is compacted, but it is literally impossible to compact it enough to match the density of the undisturbed soil in the lot.

Now, your house is built on the foundation and the landscaping is finished. Over time, the entire lot compacts, but the backfill area remains looser than the rest of the soil. Loose soil absorbs water more easily, so your lawn could be on fire, while water is literally seeping into your base. If you’re struggling with dry patches, don’t assume more water will solve the problem. Beneath your house might be wetter from your exertion.

These are the events that occur when water settles below your foundation:

1. Water causes expansive soils to swell and hydrocompactable soils to sink.

2. Fill soil is looser, so this soil moves more freely, increasing stress on the foundation walls.

3. Exterior soil pressure, as well as water pressure, weaken joints and widen existing cracks.

4. Water under the foundation traps radon, creates uneven soil moisture, and causes many other problems.

Some ways to tell if the Clay Bowl effect is contributing to your structural problems:

–You have existing cracks in your foundation that ooze water.

–Your basement has a higher relative humidity than the rest of your home.

–It has elevated radon levels and cracks in its foundation.

–Has struggled with mold issues in the past.

–You notice that the walls and/or floors of your basement appear dark in spots.