Three Causes of Foundation Settlement in Greater St. Louis

The three main causes of foundation settlement is poorly compacted soil, drying & shrinking of soil, and wetting & softening of soil.  Each of these result in problems that should be fixed quickly and effectively to prevent any further damage from occurring.

The problem of having poorly compacted soil occurs during home construction.  First, a hole is dug for the house, and the foundation is built.  Then the backfill soil is replaced, and the rest of the home is built.  The weight of the home, along with the backfill soil, adds up to a large amount of weight being placed on the soil under the home.  The weight of the home sits on three different types of soil: the native soil, fill soil, and backfill soil.  Each of these types will react or compress differently to various environmental conditions such as drought, moisture, and temperature.  As the various soils compress, and the weight of the home shifts, uneven settlement occurs.  One part of the home may sink further than other parts because of the different soils, resulting in cracks and other damages to the home.

Drying and Shrinking of the soil is be caused by moderate to severe periods of drought.  During a dry period, the soil along the sides of the home and under the footing shrinks, leaving large and unsupported voids.  Since the entire weight of the home is resting on the footing, the home settles into the gaps.  This causes cracks and other damages to the basement walls, along with cracks in upstairs walls as the home settles further and further.

When heavy rains follow dry periods, all of the incoming water now has several new pockets and channels to flow through along the sides of the foundation and under the footing because of the dry and cracked soil.  During heavy rains, the soil becomes saturated and soft, causing the foundation to sink and settle.  The uneven settlement causes cracks in the basement floor and walls and eventually in upstairs walls.

Foundation settlement is a major problem that should be fixed as quickly as possible before any further damages occur.