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Groundworks Company Installs Helical Piles and Slab Piers to Stabilize School Building in Moberly, MO.

by Holly Richards-Purpura

Foundation Settlement and Unstable Soil

Anything built on top of soil – houses, garages, businesses, schools, and everything in between – has the potential to settle. Foundation settlement happens when the soil underneath a structure is unstable and can no longer support the weight of the building. Unstable soil can happen for a variety of reasons including drying and shrinking of soil, wetting and softening of soil, and poor compaction.

When structures start to experience foundation settlement, various visible signs will give it away. These include cracks in block and brick walls, cracking drywall, sticking windows and doors, and sloping or uneven floors. It can be tempting to ignore these signs, but the longer they are neglected, the worse they and the foundation settlement will become. If there’s any question at all, it’s best to contact a local foundation repair expert for help with remedying the issue.

How Foundation Repair Professionals Can Help

When exterior wall cracks were becoming more visible and several interior doors did not function properly in a school building in Moberly, MO, the district’s director of building/grounds/safety took note. He reached out to various companies to obtain bids for repairs to the building to ensure its safety, structural integrity, and appearance.

One of these contractors was Foundation Recovery Systems, a local Groundworks company serving the area. Groundworks is the nation’s largest privately held foundation services company. A certified field inspector with the local company evaluated the 40-year-old building on the property and noted various exterior horizontal and stair-step cracks, as well as vertical cracks on some of the interior walls and sticking interior doors. He also measured between 1/4” and 5/8” of exterior settlement along the south side of the building. Varying amounts of settlement were measured throughout the inside of the building, including up to 3” in some areas of the interior slab.

The district representative wanted to not only have the building stabilized, but raised back to its original level as much as possible. The local Groundworks company inspector recommended the perfect solution to do just that – 19 helical piles for the external settling, and 30 slab piers and polyurethane injections for the internal rooms.

Helical piles are ideal to use on lighter structures – like this one-story school building – experiencing foundation settlement. Featuring round shaft helix blades, these piles are mechanically “screwed” into the ground and down to more stable soil to permanently reinforce the structure. Slab piers work much the same way, except they are specifically used on settling slabs. Each of these measures also can be used to help lift the structure back to its original level position. Additionally, polyurethane injections also can be used to lift and level sunken concrete, and they are a better alternative to older mudjacking methods.

Installation Project Overview

Once the bid and scope of work was approved by the school board, the local Groundworks company was able to complete the stabilization and lifting projects in seven working days.

The crew began with the exterior helical pile installation, first excavating 106’ around the building and digging down 4’ to access the footing. Seventeen helical piles were then installed 6’ apart along the south wall to support approximately 12-18 kips of dead load. Once all piles were installed 13-17’ down to more competent soil, additional pressure was applied to help lift this south wall of the structure 1/4”-5/8” back towards its original position. The soil was backfilled and tamped down, and seed and straw were laid over the replaced soil.

The crew then began working inside as holes were cored for the slab piers. Ground penetrating radar was used to locate plumbing and other utilities below the slab before the holes were cored for the piers or drilled for the polyurethane injections. The 30 slab piers were then installed in various rooms throughout the building, also installed 13-17’ down to more stable soil. The office portion of the building had foam injections in the past, but the soil continued to settle without the use of slab piers. In some areas the dense foam had to be chiseled out by hand to install the slab piers and bridge brackets. Additionally, 925 sq. ft. of PolyRenewal™ concrete lifting and leveling solution was installed between the slab piers and filled voids throughout the building to assist with lift. The crew was able to stabilize and lift the building back to its original position, which helped problematic doors function properly.

The concrete entryway was excavated, and the remaining two helical piles were then installed 7’ apart along the east wall to support approximately 18-22 kips of dead load. The installation depth for these piles also ranged from 13-17’.

These installations have greatly improved the building’s safety and structural integrity for current and future students, staff, and visitors.

About Groundworks

Groundworks is the nation’s largest privately held foundation services company. Headquartered in Virginia Beach, VA, the company provides foundation repair, basement waterproofing, crawl space repair and encapsulation, and concrete lifting. Groundworks is comprised of 16 brand companies, which operate out of more than 30 offices that serve 23 states. Since 1986, the combined companies have helped nearly 1 million homeowners protect and repair their most valuable asset, their home. Groundworks has been named numerous times to the Inc. 5000 Fastest Growing Companies, BBB integrity award, and Best Places to Work. For more information, visit

The Local Groundworks Company Serving Moberly, MO:

Foundation Recovery Systems
1401 US-24
Moberly, MO 65270

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