Thrasher Foundation Repair Case Studies: Foundation Piering at Elementary School

Sunday, May 20th, 2018


The new library addition at this elementary school had settled.

Foundation piering brought it back to level.

The extreme drought that began in the late spring of 2012 had devastating effects across the Midwest, particularly on lawns, crops and foundations. One building that was hit particularly hard was the elementary school in Raytown, MO. The elementary school was newly renovated and had a library added on in recent years, but it experienced differential settlement in the new library.  

The settlement in the library addition of the school had become extreme in some areas. Employees and students began to notice cracks in the foundation wall. Over time these cracks worsened and began to show on both the exterior brick walls and the interior brick walls. Eventually, the Raytown School District reached out to evaluate the problem and determine a repair plan. The school district contacted Thrasher to develop an engineered repair plan.

A resistance pier is one of the most commonly used systems for both residential and commercial foundation repair. Resistance piers not only stop settlement, but also raise the structure when desired, closing cracks and correcting other structural flaws caused by the settlement and/or ground movement.

Once on-site, Thrasher Foundation Repair performed a full and detailed inspection of the elementary school. 

Elevations were taken to determine the original height of the foundation and the current state of the foundation. Foundation and drywall cracks were also inspected, measured, and documented. 

Floor elevations and slope were also inspected and measured. Once the investigation was complete, a clear picture emerged of the foundation problem.  

The library's foundation was built on a separate footing from the rest of the structure and was shallower.  

Because of the shallow footing, the drought conditions had a more significant impact on the foundation and caused the library to settle 1.25". In contrast, the rest of the elementary school's foundation remained relatively level.   

Settling foundations are primarily the result of 3 general causes. Settling can be the result of poorly compacted fill soils. When homes and other structures are built, often the natural grade of the earth must be altered. This means that a portion of a hill may be cut away, or a low valley may be filled in with soil. When a valley is filled in, extra care must be taken to ensure that the fill soil is well compacted as the soils around it. If not adequately packed, then differential settlement can occur. The second reason foundations can settle is a result of wetting or over-saturation of soils. This can result from natural rain events, but more commonly, unsatisfactory grading, gutters, or downspouts around a home. When the ground below a footing becomes saturated, it can lose its compressive strength, and the structure can settle into the wet soil.  

The third cause of a settling foundation is the drying out of soils. When clay soils dry out, they shrink as the moisture evaporates out of it. 

This causes the soil to pull away from the foundation's bottom side, creating small voids where the foundation can settle into. At the elementary school in Raytown, the most likely cause of the setting foundation was the drought conditions drying out the soils below the footing. Regardless of the reason, the repair method remains the same. The foundation needs to be supported on steel columns that are driven to bedrock.   

For this Elementary School, Thrasher and the engineering team designed a 22 push pier and void filling solution. Once the school board approved the repair plan, Thrasher quickly installed 22 push piers for the foundation repair project. Thrasher selected SupportWorks(opens in a new window) PP288 push piers for this repair. Once all 22 piers were installed, Thrasher lifted the foundation 1.25" and brought it back to the original position. After the foundation was raised and leveled, Thrasher then lifted the slab floor with polyurethane injections. 

When choosing a contractor to repair your building's foundation, it is not only important to choose a contractor who has the right repair product for the situation, but it is also essential to select the contractor with the right expertise and experience. When choosing to work with Thrasher, you are selecting a contractor who not only knows how to do the work correctly but has over 45 years' experience doing this type of repair work. So, don't leave the work to a beginner. Hire the trusted name in the industry, and call Thrasher.