09 Dec What Causes House Foundations to Move?
In our last blog post, we discussed the warning signs to identify if your foundations are moving. The ground and soil beneath your home can become unstable and cause your foundations to move and weaken your house’s structure. In this article, we highlight the main factors that can cause foundations to move.
When the soil beneath your home becomes saturated from poor drainage or heavy precipitation, the soil swells and exerts pressure on foundations. Water can also saturate deep underneath foundations and turn the earth to mud and slush, causing the foundation to drop. What’s more, when oversaturated ground freezes, expanding columns of water force foundations upward. Additionally, a plumbing leak under a slab also causes excess moisture, making the slab heave upward from expansive soil and move your foundations.
In contrast, when there is not enough water from extreme dryness, drought, or vegetation, the ground cracks and the weight of the building compresses, causing cracks, and the foundations drop. The ground and soil contracts, shrinks and pulls away from the foundations, creating a gap and allowing for movement, which reduces the support, and the foundations shift and settle.
Poor drainage can result in too much moisture in the soil, causing foundations to move. Poor drainage can be due to negative slopes, standing water, blocked gutters, and downspouts directed towards the home. The added moisture saturates the soil, making it settle and compact, causing uneven support.
Tree roots soak up the water that keeps the soil moist. They remove the moisture from the soil too much and shrink the soil. Transpiration from plants makes the roots dessicate the soil beneath the home, causing the soil to shrink and the home to settle. This is particularly an issue with large roots underneath or next to the home, as they suck up the moisture that keeps foundations stable.
Changing weather means that the soil and earth beneath your home is in constant flux. When it rains heavily, snows, or floods, soil becomes oversaturated with water, causing hydrostatic pressure which puts pressure on the foundations, leading to cracking, shifting and leaking. If the weather reaches freezing temperatures, the saturated ground can also expand and push foundations upward. Likewise, if the soil is too dry, it contracts and takes its support with it. This constantly changing weather and constantly contracting and expanding of the soil results in weakened foundations.
The way your foundations were laid and the ground they were laid upon also affects your foundations. If quality building materials were not used, foundations will be weaker and more susceptible to movement. Likewise, if the soil beneath your home was not prepared correctly, and it was backfilled without being sufficiently compacted, or substandard materials were used, your foundations will be more likely to move.
When soil is not properly compressed beneath the home, the weight of your house upon it leads to issues, particularly when cut and fill methods have been used. The type of soil also impacts movement. Sand does not support foundations very sufficiently, and clay expands and shrinks, leading to pressure, lack of support, and upheaval. Soft, low-density soils present issues, as does consolidating soil, which dries and constricts, leaving a gap and room for movement.
If you are experiencing foundation stability issues, it is important that you address the causes early to prevent them from leading to long-term damage to your property.