Foundation Repair Case Studies: Settling Porch with Stone Foundation Stabilized in St. Louis, MO

Tuesday, July 23rd, 2013 by Tim Warchol

Challenge

Settling Stone Foundation

This St. Louis, Missouri home is approximately 90 years old.  Over the years, the foundation had settled, causing the roof over the porch to be pulled away from the structure.  This allowed water to seep into the framing of the roof and ceiling under the roof.  As the foundation settled, cracks in the stone foundation and brick above were created.  Approximately 8 years ago, the customer hired a contractor to install concrete piers to arrest the settlement.  This repair was unsuccessful and the contractor that installed the concrete piers could not be located.

Solution

Steel Piers

The customer hired a structural engineer to help with the design of the needed repairs for the porch foundation.  After a visual inspection, the engineer contacted Foundation Supportworks by Woods to consult on the repair design.  Lifting the foundation was discussed, but it was decided that additional damage would be incurred while lifting an older stone foundation and masonry structure, therefore, stabilizing the foundation was the desired outcome.   It was determined that ten (10) model FSI288 push piers and some components of the Geo-Lock wall anchor system would be utilized in the design.

The design consisted of a concrete wall being constructed up against the outside of the existing stone foundation wall.  The new concrete wall would be tied to the stone foundation using components of twelve (12) Geo-Lock wall anchors; specifically the all-thread rods and 4” X 4” backup plates.  During excavation, the existing concrete piers were uncovered and some of the stones started falling out of the foundation.  Entry into the crawlspace under the concrete porch was established, and upon entering the crawlspace, it was uncovered that the mortar holding the stones together was in bad shape.  The mortar was loose and powdery.  The structural engineer was brought in to consult, and it was determined that a second concrete wall needed to be constructed on the inside of the crawlspace against the stone foundation, and some of the piers would be placed on the existing concrete piers with the addition of one (1) pier. 

The next hurdle was to determine how to get the concrete into the crawlspace to pour the wall.  The solution was to hire a concrete pump, and use a “Torpedo” concrete mix, so the concrete would flow through the hoses, and into the forms in the crawlspace.  After the concrete walls were allowed to cure, the FSI288 push pier tubes were advanced, approximately 45 feet deep to competent bearing material.  The brackets were then attached to the tubes and pressured up against the concrete foundation, and then the excavation was backfilled.  With the project complete, the foundation will be free from settlement from now on.

Project Summary

System Design Specialist: Tim Warchol

Project Foreman: Chris Blickenstaff

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Woods Basement Systems, Inc.
524 Vandalia Street
Collinsville, IL 62234
1-618-708-4055