Solving Foundation Settlement

When a structure has experienced settlement, it is important to solve this problem befofe addtional structural damage takes place. Underpinning or piering is the process which transfers the weight of the structure which is sitting on unstable soil to bedrock or firm bearing strata by using steel piers.

Push piers consist of sections of galvanized or epoxy-coated steel pipe that are driven into the soil with a hydraulic ram.  Helical piers use screw piles with steel shafts. The lead section, with one or more helixes attached, provides the needed bearing capacity. The piers are screwed into the ground with a hydraulic torque motor.

With either system, one or more steel piers are driven to rock or a suitable soil bearing layer and are connected to the foundation through a pier bracket. Once a suitable bearing stratum is reached, each pile is tested to a force greater then required to support the structure.

Hydraulic jacks attach to the embedded steel piers and are used to raise the foundation back to its original elevation. Once the structure is restored to the desired elevation the piles are affixed (bolted or welded) to wall brackets, locking the new elevation of the structure.

Typical Steps in a Piering Installation

1. An excavation is made adjacent to foundation and approximately 10" below the grade beam.
2. Soil is scrapped from the footing bottom and the foundation is chipped smooth to ensure proper fit of support bracket.
3. Brackets and hydraulics are installed and a guide sleeve is advanced through the support bracket.
4. Starter and pier sections are advanced to refusal
5. The last pier section is cut approximately 5" above the support bracket and a fastening plate is installed on top of the pier column.
6. The hydraulics are reconnected and are operated sequentially to raise the structure.
7. When the structure has been raised to the desired height the fastening plates and support bracket are permanently attached to the pier column.
8. When the structure is secure, depth, pressure and elevation readings are recorded for each pier.
9. The excavated soil is replaced and compacted.
10. Shrubbery and concrete removed for the pier installation is replaced.