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 soil becomes muddy and unable to support weight. Too little moisture and the soil breaks up into its individual particles and is carried away by the wind.

Dry soil also decreases the depth of plant roots because plants spread out 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 soil around our houses begins to blow, and many of our plants produce less. All of these factors make our yards and homes feel hotter and our allergies strike up more often. We also start to notice burnt patches on our lawns and brittle leaves on our plants. In an effort to counteract these problems, we water more. For some reason this doesn’t seem to help.

That’s because most of us are also fighting a layer of hardened clay under the grass, which is literally diverting water into the nearest permeable soil. Unfortunately, the end result can be that water intended for your lawn is forced into the soil below your foundation; this is called the “clay bowl effect”. It works like this: houses are built by digging or digging a hole where the foundation will go. Naturally, this hole has to be wider than our foundation because people and machines also need space to work. Once the base is poured and dries, 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 complete. Over time, the entire lot compacts, but the fill zone remains looser than the rest of the soil. Loose soil more easily absorbs water, so your lawn could be on fire, while water is literally seeping into your footing. If you’re struggling with dry patches, don’t assume more water will solve the problem. Underneath your house it might be wetter from your effort.

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

3. The pressure of the external soil, as well as the pressure of the water, weaken the joints and widen the existing cracks.

4. Water under the foundation traps radon, creates uneven moisture in the soil, and 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 house.

–It has elevated levels of radon and cracks in its foundations.

–You have struggled with mold problems in the past.

–You notice that your basement walls and/or floors appear dark in places.