Project Manager: Dave Cummings
Job Purpose: Foundation Stabilization & Basement Wall Repair
Foundation Contractor: Koster and Steigenga
Koster and Steigenga Construction, residential contractors, was commissioned to remodel a portion of a house situated on a high hill overlooking a lake, but close to the edge of the steep incline down to the water. Since the soils were largely moderately loose sand, the dynamics of weather, erosion, and surcharge loading of the house, over time, caused the soil to slough which allowed one wing of the house to settle.
While not apparent at the beginning of the work, it quickly became expedient that something needed to be done. Soils and Structures, a prominent engineering firm, was called to evaluate the problem and to design appropriate repairs.
They were quick to suggest Kent Companies and helical piers. Being vibration free with easily measured capacity, we were the perfect solution.
Stabilizing the Home
The footings required 7 vertical helical piers, each demonstrating 36,000 pounds capacity, ultimate. 5 of the piers used conventional lengths of the 2 7/8 schedule 40 helicals to an average depth of 20 feet. This transferred the point load of the foundation to the stiffer soil stratum below the sloughing zone, giving the owner true stability. 2 of the piers needed to be installed in a low overhead location. Kent Companies adapted by using a specialty short section pier that allowed installation to full required capacity.
The Required Design for the Basement
The design called for 2 tiebacks because the one wall was tipping out. The required 4,000 pound ultimate capacity, providing a factor of safety of 2, was easily provided, using 1 1/2 inch square shaft helical tiebacks which are ideally suited for tension applications.
The work was completed in less that two days to the full satisfaction of everyone, with very little site disturbance, no big equipment, no vibration, and all capacities met.