Fifteen, two‑unit condominium buildings exhibited differential settlement and interior slab movement from loose organics and voiding, risking structural performance and livability. Continuous occupancy required a rapid, low‑disruption remediation strategy that delivered durable lift and stabilization. The job was completed by foundation repair specialists at Helicon.
Initial Assessment
Investigations confirmed loose to very loose near‑surface soils, voids at 3–8 ft below the surface, and active settlement beneath slabs and footings under service loads; full replacement was not viable due to resident displacement, extended schedules, and higher cost risk.
Proposed Solution
The experts at Helicon selected AP Lift 430 for its hydro‑insensitivity, rapid reaction, and ~50 psi compressive strength to permeate, densify, and lift with minimal downtime.
Procedures
- Grid the interiors; mark piles, grout points, and quality control benchmarks.
- Inject low‑mobility compaction grout to seal limestone and pre‑densify.
- Install underpinning to ~36 ft, using predrill/sleeves to bypass clays.
- Inject AP Lift 430 at 8/5/3 ft below land surface to lift slabs and encapsulate organics.
- Monitor elevations/pressures; proof‑load and video‑verify.
Results
- Restored slab elevations and footing support with no resident displacement.
- Completion in days to weeks vs months for replacement.
- Approximately 80-90% cost savings versus full demolition/rebuild approaches.
- Durable, closed‑cell, water‑resistant stabilization for long‑term performance.
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