Foundation damage can occur for several reasons, from the soil quality to the underlying bedrock in the area and the weather patterns throughout the year. We’ll discuss how each of these factors puts your home’s foundation at risk of instability and leaking.
Rapidly-Draining Soil
Soil contains three constituents in varying ratios: clay, sand, and silt. The soil in Williamson County is overwhelmingly silty, which means it’s prone to rapid and excessive draining. This type of dirt is problematic for concrete foundations for two primary reasons.
First, the large particles are easily influenced by runoff following precipitation. Rainfall draining into the earth can erode the ground that typically provides support to your concrete. The gradual erosion of the soil can leave your foundation unsupported in some areas where the runoff is heavier or where the earth isn’t sufficiently compacted.
Eventually, the soil movement can lead to differential settling of your foundation, which is when areas of your home lose support from underneath and settle more quickly into the ground. Differential settling can quickly create structural instability in your home, potentially compromising the entire structure’s integrity.
Second, the erosion from runoff very often occurs directly against your concrete, creating voids that collect water during rainfall. The runoff can remain in contact with your concrete in these voids for extended periods, contributing to problems with water intrusion and moisture accumulation under or inside your home.
The water has the opportunity to wick through pores or cracks in the concrete and create a myriad of issues in your crawlspace, basement, or living space.
Above-Average Rainfall
Silty soil is most problematic for foundations during rainfall when runoff can pull soil particles downward and contribute to differential settling. Unfortunately, the issues with loose silt particles in Franklin’s soil are made more severe by the above-average rainfall in the area. The city experiences around 52 inches of rain each year, which is nearly 50% higher than the national average.

The excessive rain exacerbates the potential damages caused by the soil composition. More rain means a higher chance of erosion and differential settling. It also lends itself to water and water vapor problems, as it fills the voids around your concrete and exposes the porous building material to moisture more often.
Drought
Drought has long been an issue for Franklin, as the moisture in the ground is reliant almost entirely on precipitation, which fluctuates throughout the winter and summer. Although much of the year brings heavy and frequent rainfall, the higher rate of evapotranspiration of the water out of the soil in the summer can cause the ground to dry out.
Although the earth in Franklin has a relatively low concentration of clay particles, the clay that is present naturally causes the ground to shrink slightly. During particularly dry periods, even minor losses of ground volume can contribute to differential settling.
Shallow Frost Line
The frost line in Franklin, which refers to the depth to which the water in the ground freezes during the winter, sits at a very shallow 12-18 inches below the surface. When the water in the dirt freezes, it expands and can place undue inward pressure on your foundation walls or upward heaving under your slab.
Over time and in combination with shifting soil, the pressure caused by the shallow frost line in Franklin can contribute to differential settling, foundation cracks, and water intrusion.
Limestone Bedrock & Sinkholes
Lastly, the bedrock that lies under Franklin is problematic for home foundations. It’s mostly made up of limestone and dolomite, both of which dissolve when exposed to water.
Runoff from precipitation and groundwater can both contribute to the erosion of the bedrock, creating underground caverns and tunnels through which the water drains.
This phenomenon, called karst, eventually creates instability in the soil above, which in turn can leave your foundation without the support it requires to bear the weight of your house.
Karst is the primary cause of sinkholes in Tennessee, which can promote structural problems in your home’s foundation.
