There are several factors contributing to the prevalence of foundation problems in Mechanicsville, most relating to the geology and climate in the region. We’ll discuss the specific underlying causes of foundation damage below.
Expansive soil is one of the most significant issues that causes foundation damage in Virginia. The earth underlying Hanover County is varied in composition, but most of the ground is characterized by an abnormally high concentration of clay. The expansive clay soil in Mechanicsville causes a variety of issues for home foundations.
First, clay soil is referred to as expansive because of its tendency to swell when it gets wet. Clay particles are tiny, and the small gaps between them naturally attract and absorb large quantities of water.
When runoff soaks into the ground, the soil swells and pushes against your foundation. The inward hydrostatic pressure on your walls and upward stress on your slab can create fissures that compromise your foundation’s structural integrity.
Second, the volume gained during rainfall is lost during periods of little or no precipitation.
When runoff eventually drains deeper into the earth, the soil that normally provides support for your concrete shrinks and pulls away. If the drying process occurs uniformly under your home, the foundation simply settles into the ground.
However, uneven drying can lead to differential settling, which leaves sections of your concrete foundation with unequal support. The areas that dry more quickly will sink further, sometimes cracking away from your home if the settlement is substantial.
As you might expect, differential settling often results in structural problems that require expensive repairs.
Finally, clay is more absorbent than silt and sand, which means the soil in Mechanicsville soaks up and retains water more readily than typical dirt.
Runoff that remains suspended in the earth and continuously in contact with your foundation can seep through the concrete and contribute to water and moisture problems under your home.
The adverse effects of expansive soil are made worse by regular and concentrated rainfall. Unfortunately, the Richmond area, including Mechanicsville, typically gets over 44 inches of rain annually.
This is around 150% of the national average, and the excessive runoff that results from the heavy precipitation increases the likelihood of foundation damage.
The moisture content in the soil around your foundation is replenished frequently by the rain, increasing the occurrence of ground swelling and the risk of excessive and damaging hydrostatic pressure on your concrete.
Additionally, the continuous exposure to moisture makes water intrusion and water vapor more prevalent in the area.
Lastly, flooding is a common occurrence in Mechanicsville for several reasons. There are many floodplains throughout the city that can get flooded with overflow from rivers and waterways. This type of flooding is most common during heavy rain, which the region frequently experiences.
Even the homes outside of the flood zones are at significant risk of flash floods. Flash flooding is an issue in Mechanicsville because the above-average rain soaks the clay soil quickly and regularly, and the ground in the city naturally drains very slowly.
Even routine thunderstorms can cause the runoff to back up to the surface and create instances of flooding.
The risk of flash flooding is most significant during hurricane season when hurricanes and tropical storms bring concentrated precipitation to the area.
The absorbent soil is often unable to drain the excessive runoff quickly enough, so it persists on or above the surface.
Flooding generally maximizes the hydrostatic pressure against your slab and crawlspace or basement walls, increasing the risk of structural cracks forming to relieve the stress. It also contributes to water intrusion and excess moisture wicking through your concrete and affecting your under-home area and living space.