Tar Heel Tip of the Week: Causes of Foundation Settlement

Monday, September 12th, 2016 by Jaimie Hooker


Your home is resting upon many different layers of soil, each with different thicknesses and abilities to hold the weight of your home. Some layers were carried and deposited by water, some by the wind and some by glaciers. Some layers may have even been put under your home by your home builder, who commonly moves soil around to create flat, buildable lots of land.

Causes of Foundation Settlement

Typically, soil layers get stronger with depth. In most locations you will find a shallow layer near the very surface, making it easy for plants and other vegetation to grow. In Tar Heel Basement Systems’ service area, you will find more clayey soils. Deep below the layers of clay is a soil layer of bedrock, which is very stable, dense soil.

Different soil types are affected by moisture in different ways. Clay soils are one of the most common soil types. When clay is wet, it holds onto water and expands in size. When clay is dry, it shrinks.

Foundation settlement is the movement your home experiences when the soil below can no longer support the weight of your home. There are three commons changes in soil that cause settlement.

1. Dry and Shrinking of Soil

Drought- After many months or years of drought, clay soil dries out. As stated before when clay is dry, it shrinks.  As the amount of soil around your home shrinks in size, it creates an empty space for your home to settle into.

Maturing Trees- Did you know the root system of a tree is often two times the size of the tree canopy? This means, a tree with branches that extend over your home, most likely has roots that extend under your home, drawing valuable moisture from the soil.

2. Wetting and Softening of Soil

Heavy Rains- As clay soil gets wet; it holds on to the water and becomes very soft. This soft soil can be weak, causing the home to shift or sink down into it.

Poor Drainage- If water is allowed to stand or pond next to your home, the soil will absorb the water and again, weaken the soil.

3. Compression of Poorly Compacted Fill Soil

A common practice when developing neighborhoods or involves removing soil from hilltops and placing it in valleys to create flat, buildable lots. If this new soil is not compacted correctly, it will compress under the weight of your home and cause settlement.

Now that you know the three most common types of foundation settlement, you can become more aware of the overall health of your home’s foundation. If your home may be experiencing signs of foundation settlement, or if you’re interested in a foundation check-up to see if your home could be settling, call our office for a free consultation.

About the author
Jaimie Hooker is the Assistant Marketing Director at Tar Heel Basement Systems; authoring case studies, technical papers, creating and captioning photo albums and managing website content. She also oversees the organization of video testimonials, shows and events, Jaimie lives in the small town of Madison, NC with her husband, Paul, and 3 year old son, Franklin.