Oklahoma City is a hot spot for foundation problems for several reasons, most of which are related to the city’s soil and weather. We’ll include more specific information on each factor below, along with an explanation of how each contributes to damages.
OKC is located in the Renfrow-Kirkland-Grainola-Bethany soil association. The ground in this region is predominantly clay, making the ratio of tiny clay particles to larger silt or sand particles very high. The concentration of clay makes the earth expansive.
Expansive soil has several properties that make it a significant problem for foundations constructed in the area.
The first problematic quality is the soil’s ability to swell when it gets wet. The small gaps between the clay particles attract water and can hold large quantities. When the ground is soaked with runoff, the dirt around your home expands.
The growing soil places added hydrostatic pressure on your slab and foundation walls. The concrete can crack in response to the stress, causing instability and structural damage.
Expansive soil is also dangerous when it loses its moisture content, as it also loses the volume it gained from the runoff in the first place. As rainwater drains deeper into the ground, the soil around your home shrinks and can pull away from the concrete.
Unsupported areas of your foundation will sink into the ground under the weight of your house.
Differential settling often occurs beneath your home because the soil can dry at uneven speeds. When this happens, portions of your concrete can sink more rapidly than others. If enough settlement of certain sections takes place, they can crack off your house and leave you with costly structural repairs.
The last problem with expansive soil is that it retains water for longer than less clayey dirt. This means that moisture from runoff will persist in the ground for days or even weeks after rainfall.
Your foundation will be continuously exposed to moisture for that time, increasing the likelihood of water or water vapor getting through the concrete and accumulating beneath your home. As a result, water damage and problems with high humidity both plague Oklahoma City.
Concentrated Rainfall & Drought
Oklahoma City residents enjoy four distinct seasons, and they’re accustomed to excessive rainfall and severe weather in the spring and early summer from around April to June.
The annual average rainfall in the city is around 34 inches, which is just over the national average. However, April begins a several-month-long stretch of heavy, concentrated rain, with about two to four times the monthly precipitation the rest of the year.
The abundant rain from April to June keeps the ground saturated for long periods, making dangerous soil expansion and the resulting hydrostatic pressure on your foundation more likely.
Additionally, the runoff remains suspended in the earth and exposes the porous concrete under your home to moisture on a constant basis. This makes the threat of water and moisture problems significantly higher.
The cyclical nature of the weather from abundantly wet in the spring and early summer to drought-like conditions throughout the rest of the year contributes to excessive ground movement from constant swelling and shrinking.
The result is gradual ground instability and uneven settling beneath your home, making differential settling a more significant threat.
Lastly, Oklahoma experiences an abundance of earthquakes, sometimes more frequently than California and other earthquake-prone states.
There are numerous faults running beneath Oklahoma that contribute to ground shaking. However, experts believe that industrial wastewater disposal is largely to blame for the recent increase in the number and severity of quakes in the area.
Earthquakes can shift the soil and cause instant movement beneath and around your foundation. Fissures can form if excess pressure is placed on any area of your concrete, and structural damage can result if the shaking increases differential settling or the stress on your foundation walls.