Partners (Number 2, 2008)

Spotlight on the District

Mississippi: Yazoo Clay, A Costly Challenge to Construction

When driving through the many beautiful old neighborhoods and new residential subdivisions of Jackson, Mississippi, it's not unusual to see substantial cracks in the sidewalks and streets. Those who aren't from the area might attribute the damage to tree roots or subpar concrete work. However, Jackson natives will probably know that the culprit is a geological phenomenon called Yazoo clay.

Yazoo clay, which causes cracked home foundations, cracked walls, sticking doors, popping windows, crumbling bricks and plumbing leaks, has been an expensive nightmare for contractors and homeowners who are often faced with costly repairs. Foundation cracks can also harbor molds that cause serious health problems.

Deriving its name from the Yazoo River, Yazoo clay is a mineral-filled mud with elastic properties—it can shrink and swell dramatically, causing sometimes severe structural damage to anything constructed on it. This peculiar kind of earth is located mainly in Mississippi in a geographic area approximately 40 miles wide and 120 miles long. The swath of Yazoo clay extends from Yazoo County to Scott County, stretches on to Madison and Hinds counties and crosses the Pearl River. A total of 11 counties in central and eastern Mississippi are affected by Yazoo clay.

Industry reports estimate that up to 65 percent of homes in the metro Jackson area have been damaged to some extent by the movement of this clay. The severity of the damage depends on how far below the surface it lies. The depth can range from 6 inches to 15 feet. When preparing for new construction, the clay can be removed or, in some cases, a special concrete "floating slab" can be constructed on top of the clay. If these measures fail to control the problem, tedious repair work and costly foundation adjustments may be required. When large commercial buildings are affected, repairs may involve digging 25 to 30 feet below the surface to construct concrete pilings.

Although builders have some effective remedies for the Yazoo clay dilemma, problems persist. Part of the reason is that costs associated with offsetting the clay's effects can be significant. Unscrupulous builders looking to cut costs too often fail to remove the clay or prepare the foundation inadequately before building the home. Owners of older homes may not be able to afford the necessary repairs when these problems occur.

New homes come with a six-year implied warranty, according to the Rundlett Law Firm in Jackson, which specializes in personal injury claims. These warranties transfer to subsequent owners when a house is sold. In addition, a homebuyer who has purchased an older home with foundation problems that have not been disclosed may be entitled to recover damages for home defects.

Considering the additional costs to developers of new construction and the millions of dollars paid annually by homeowners to make repairs to their homes, the economic impact of the Yazoo clay phenomenon is substantial. However, home buyers can save money if they are aware of the problem of Yazoo clay, require soil tests prior to purchase, and make sure the developers prepare the home's foundation carefully. When purchasing an existing home, the buyer should require the seller to make any necessary repairs.

This article was written by Michael Milner, senior regional community development manager at the Atlanta Fed's Birmingham Branch. We wish to acknowledge work by Lynne Wilbanks Jeter, which appeared in the Mississippi Business Journal.