Foundation Repair Case Studies: New Construction Piering
Challenge
The builder found large amounts of uncontrolled fill during construction of this new home.
Micropiles are a solution for expansive soil and bedrock challenges.
In 2016, a local home builder was in the beginning stages of constructing a home when they noticed a problem they could not ignore. The home builder discovered large voids and very rocky soils as they excavated the ground in preparation for the construction of the home's footings and foundations.
The voids were so large, and the soil was so unforgiving that the home builder could not in good conscience build a new structure on this site without taking proper precautions.
The homebuilder made the right decision and decided to slow the progress on the home's construction until he could have a site inspection and review and complete any potential needed repairs. The builder called Thrasher Foundation Repair to help identify the causes of the problem and any possible repair option.
While on-site, the Thrasher field representative performed an investigation. The field rep took samples of the soil and rocks back to the office for further analysis. He also measured and probed in the voids in the ground to determine the gaps' size and condition. It was quickly resolved that this site was not constructive as it was, and site improvements needed to be made before any further home construction took place.
The general repair plan was to install a new construction piering system and to fill all identified voids in the soil. While this available repair model seemed to be reasonably straightforward, the job site's complexity made it a non-typical install. The piering system had challenges associated with it. Typical new construction piers are Helical Piers, which act as very large screws or augers that advance into the soil. While these piers are typically a great product, they would not work in this situation. The rocky ground would not allow the helical pier to advance beyond the shallow rocky soils and never let the piers achieve bedrock depth.
The other issue that presented itself was that all voids needed to be filled with structural grout. Still, without being able to measure the gaps fully, there was no way to make an accurate guess on needed supplies and materials.
Solution
Due to the large rocks and void spaces encountered at the new construction site of this Shawnee home, Thrasher recommended installing grouted micropiles. It was determined that the voids in the ground needed to be filled with flowable fill during the installation. Thrasher pumped the flowable fill below the ground under this home's footprint to stabilize the soil and fill the voids.
Thrasher installed 21 grouted micropiles and pumped in 42 cubic yards of flowable fill in less than one week. This put the construction of this home back on schedule.
