What Causes the Ground to Move Under a House?

Moisture Level Changes

• Underground water changes can affect the soil above. Oversaturated ground can shift and allow the foundations of houses to sink. A winter with a lot of snow or rain and constant freezing and thawing, can cause shifts in the surrounding soil. When underground water freezes, it can cause the surrounding dirt to "heave." Soil that is exposed to extensive heat or drought can crack and subsequently shrink, causing shifts under the foundation.

Poor Ground Compaction During Construction

• Many new homes are built on a slope to improve drainage and run-off of surface water. While this helps to avoid water damage due to flooding, it is usually an indication that fill dirt was placed over the building site to make it level for the house construction. Some dirts are expansive and require additional time to "settle," which is not a fast process for any new home. Many homeowners of new houses find popped nails and cracks appearing within one to two years of construction. Typically, the soil will eventually settle into its permanent spot under the weight of the home; however, this will vary with each home and the surrounding soil conditions.

Tree Roots

• Trees push their roots deep into the ground to search for water. Many newly-constructed homes have immature trees planted for lanscaping beauty; yet in a few short years, as trees mature and grow, the roots can begin to move the foundation, or the ground around it. If the surrounding dirt is clay, tree roots can create an unstable environment by pulling the moisture from the ground. Examine the trees to see how close they are growing to the affected foundation; if the tree's branches are touching -- or nearly touching -- the exterior of the house, it can be assumed that the roots are also touching the foundation. Root barriers can be placed around the foundation, but are typically an expensive fix in relation to transplanting or removing the tree, or cutting back the roots that are touching the foundation wall.

Nearby Roads & Streets

• Concrete expands when it is heated and shrinks when it cools. As roadways expand in summer heat, they can push against driveways, which then expand into the foundations of adjoining houses. Expansion joints and deflection gaps in the foundation can compress as the house ages and deals with continual ground movement; eventually, the foundation can begin to buckle from the surrounding from the surrounding pressure.