So if the soil rises when it gets wet and falls when it dries out, what should I do as a homeowner? Structural Engineers recommend keeping the soil moisture as even as possible throughout the year to minimize the swelling and shrinking cycle of clay soils. Let's take a look at how to do this around the home:

Avoid excessive wetting near the foundation
Two steps are necessary to do this:

First, the soil should slope away from the home on all four sides if possible. This sends the water away from the foundation. Engineers recommend soil slope to be at least 6 inches of fall in the first ten feet from the house. Flat soil grading is not good; sloping towards the house is worse. 

Brick planters- I often see brick planter boxes next to the foundation on homes that I inspect. These walled in planters are catch basins for rainwater and will flood the foundation. Sometimes I even see gutters that drain into the planter boxes. If you must have planters next to the home make sure that water can pass through the planter box walls (leave air spaces and don't seal the bricks with mortar). The ideal is to remove any  planters that are next to the foundation. 

Air conditioner drain lines- This is another source of excess water next to a foundation, as they can drip five gallons of water a day onto the soil. The air conditioner drain line should extend five feet from the house to keep water away from the foundation.

The other step in keeping clay soil stable is to not let it dry out. Notice in the photo how the soil is pulling away from the foundation. When you see this condition, a gap is also forming below the foundation, causing the home to settle down onto the soil below.

Never allow the soil around the foundation to dry out.
During dry periods, water the soil around the foundation with a hose. Do not shoot water down into the gap; water about one to two feet from the edge of the slab. Come back in a few hours and you will see that the gap has closed from swelling. This is a good sign that the soil is back in contact with the foundation. In very hot weather it may be necessary to do this once a day until the next rainfall. Clients often ask about using soaker hoses. This is ok, but don't forget about the hose and leave it running. I personally feel that hand watering is the preferred method. Sprinkler systems are also great tools for keeping the soil evenly moist around the foundation- just don't allow them to run too long, and add a rain sensor so the system shuts off during rain.

In summary, proper yard slope and gutters keep the soil from swelling caused by flooding. Watering the soil during dry seasons keeps the soil from shrinking. Even moisture throughout the year is the key to a happy and healthy foundation. 

We hope you find this information to be useful for taking care of your home's foundation. Please keep us in mind if you know of someone who is buying or selling a home.

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