Foundation Repair Case Studies: Foundation Piering at Commercial Office Building

Thursday, April 12th, 2018

Challenge

This 3-story office building in Overland Park had settled to the point that a window cracked.

Thrasher received a call from a local engineering company to assist in designing a plan to correct the  foundation settlement problems.

The construction of this medical treatment facility was very unique and complex.  It had multiple foundation types and settlement was occurring on all of them.  To properly stabilize and repair the foundations of this structure, Thrasher had to utilize many different types of piers both on the inside and outside of the structure.   To add to the complexity of this project the facility was to remain open during the repair work, but dust and debris had to be limited and not impact the day-to-day functions of the medical facility.  To accommodate the customer, Thrasher installed the piers on the interior of the structure after regular business hours.   Also, during the he inside installation process all the debris and dust was collected, contained, and segregated from the operational facility.

Combined with the resources of SupportWorks, Thrasher has over 50 different types of pier brackets to choose from when repairing projects.   While there are many different types of piers that can be installed based on the foundation that is being repaired, the style or installation method for piering systems boils down to 2 distinct methods.   Piering systems can either be a resistance pier or a helical pier.  Both pier systems offer significant benefits, but they are not equal in application.

Helical Piers, typically are made of steel tube with 2.88” outside diameter.  The first 7’ installed will have multiple helix blades welded to the center pier tube.   The leading section of the helical pier is installed or screwed into the ground and pulls itself down while the pier is turned with a hydrolic drive head at grade.   The helical pier will pull itself to bedrock while extension are added at grade level.   This system can be designed to a significant variance in capacity based on the soil composition and the number and size helix blades used.  This range of product design allows Thrasher and the engineers to partner in the design of the system and maximize the capability of the piers while minimizing the cost.    Helical piers are an excellent system for light structures or new construction builds when the soil composite is known. 

Resistance piers is the other general style of piering system.  A resistance pier refers to the installation process of hydraulically driving pier tubes straight down into the soil.  In order to achieve the pressure, need to push the piers into the ground, their must be a resistance force of equal or greater weight.   Resistance piers relay on the weight of an existing structure to be the counter weight when hydraulically driving the piers.  Obviously resistance piers only work as a repair option for existing foundations.  Resistance piers are heavily used in retrofit repair applications for 2 reasons.  First the equipment needed to install resistance piers is smaller and more portable.  This makes it ideal in retro fit applications where space and clearance is often a challenge on the job site.   The second reason resistance piers are often sought out as the repair option is that these piers are proof tested at the time of installation.  As a resistance pier is installed it relays on the weight of the structure to advance the piers.   Once installed the weight of the structure can immediately be transferred to the pier and an attempt to lift the foundation can be made.  During the installation and lift process, the resistance piers are naturally proof tested and proven to work.  Resistance piers offer the unique benefit of being tested during the install. 

For the medical treatment facility, Thrasher installed a total of 46 piers.  Those 46 piers consisted of helical piers and resistance piers and had 5 different styles of bracket to foundation connection.  Once all 46 piers were installed, the foundations weight was transferred to the piers, and then lifted.  The foundation was lifted a total of 2 inches and put back into a level position.  In total the project took only 3 weeks to complete, and the facilities impact to their business was minimal.  

When choosing a contractor to repair or upgrade your buildings foundation, it is not only important to choose a contractor who has the right repair product for the situation, but it is also important to choose 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 work.  So don’t leave the work to a beginner, work with the trusted name in the industry. Call Thrasher.