The damage caused by most natural disasters like earthquakes, floods, and sinkholes is easy to see—damage caused by drought not so much. However, just because you can’t easily see the damage doesn’t mean it’s not happening. Drought can cause severe structural damage to a foundation.

In this article, we’re going to define a drought, discuss how certain soil types make a foundation more susceptible to damage, repair options, and more.

What exactly is a drought?

According to National Geographic, a drought is a…

‘’…period of time when an area or region experiences below-normal precipitation. The lack of adequate precipitation, either rain or snow, can cause reduced soil moisture or groundwater, diminished stream flow, crop damage, and a general water shortage.’’

On top of all that, droughts can also cause significant foundation damage.

Droughts can last anywhere from a few weeks to a decade or more, and it isn’t always easy to say when a drought starts and stops. But, even a drought lasting only a few weeks might be enough to cause foundation damage.

Here’s how we explain the effects of drought to California homeowners:

Everyone’s home moves up and down as the seasons cycle between wet and dry. One door works better during the summer while another door works better during the winter. This is perfectly normal. However, some homes have areas that sink slightly more during the dry season than they raise back up again during the wet season. (There are various reasons for this including the house’s weight and the properties of the soil under it.) This settlement may not be noticeable over just one or two years because it’s so slight, perhaps only 1/8” or 1/16” lost each year. However, these small amounts add up. That tiny 1/8” each year becomes 1-1/4” over 10 years and 2-1/4” over 20 years. This kind of settlement will definitely be noticeable. Add to this the fact that during a drought the dry season is longer than the wet season, so the house will sink even more during a drought year. Right now people who have been in their homes for 10-20 years are calling us and saying, ‘’We knew we had a small amount of settlement, but it got worse this past year.’’

As of February 2019, the town of Arbuckle has sunk over 2 feet due to drought. What’s going on under your home is similar but on a much smaller scale.

Expansive clay soil causes the most foundation damage during a drought

To understand drought, you first need to understand soil because certain types of soil put your California home’s foundation at greater risk of suffering drought-caused damage.

There are four main soil types: sandy, silty, clay, and loam. Each of these soil types reacts differently to weather changes involving water. Foundations built on expansive clay soil fare the worst during droughts because clay soil expands when it soaks up moisture and then shrinks by that same amount when it dries out. In the next section, we’ll discuss how this feature of clay soil can cause structural damage to a foundation during a drought.

Many homes in California sit atop expansive clay soil.

An infographic with information about soil types and foundation construction

How does drought affect the soil underneath your home’s foundation?

As we pointed out above, expansive clay soil swells when it absorbs moisture and shrinks when it dries out. Parched clay soil – the kind that happens during droughts – shrinks and can create voids under a foundation. When the house starts to sink into these voids, it will develop foundation problems.