FM-PP25 PushPier™ System
The FM-PP25 PushPier™ System is a hydraulically driven steel underpinning solution engineered for stabilizing and re-leveling existing structures. Unlike driven or helical piles, FM-PP25 segments are pressed to refusal using a hydraulic ram that reacts against the structure’s weight. When installation pressure is sufficient to initiate lift, the pier has achieved the required working capacity. Constructed from 3½″ Schedule 40 ASTM A53 Grade B steel tube with a 12″ × 6″ × ½″ A36 top plate, FM-PP25 is ideal for foundation remediation, slab lifting, and retrofit support in constrained access sites.
Technical Specifications
| Pier Type | Hydraulically driven resistance (push) pier; refusal-based installation |
| Pipe Material | ASTM A53 Grade B, 3½″ Schedule 40 steel |
| Pipe Diameter (O.D.) | 3.5 in (88.9 mm) |
| Wall Thickness | 0.216 in (5.49 mm) |
| Top Plate | 12″ × 6″ × ½″ A36 steel flat plate |
| Ultimate Compression Capacity | 40 tons |
| Allowable Working Load | 30 tons |
| Section Lengths | 12″ nominal segments (stacked via couplers) |
| Connection Type | Full-penetration welded • Threaded coupler • Coupler joint |
| Corrosion Protection | Bare steel • Epoxy coated • Hot-dip galvanized |
| Embedment Depth | To refusal (varies by site; capacity verified by hydraulic pressure / lift) |
| Warranty | Lifetime, transferable |
Applications
- Foundation underpinning and settlement remediation
- Slab re-leveling and structural lift
- Retrofit support in restricted-access areas
- Load transfer to deeper competent strata
Installation Overview
Pier sections are hydraulically driven using a ram reacting against the structure. Segments advance until installation pressure indicates adequate bearing; once pressure build-up initiates lift, the design working load is achieved. Heads are cut to grade and welded/bolted to the 12″ × 6″ × ½″ A36 plate for integration into footings or grade beams.
Field note: A 3½″ pipe typically requires a field acceptance of ≥30 blows/ft when hammer-driven. For push piers, acceptance is verified by hydraulic pressure and lift (see Proof Test section).
Proof / Load Verification
| Verification Method | Hydraulic pressure × ram area; verify lift initiation and hold criteria |
| Typical Proof Test Schedule | Incremental holds at 0.25DL, 0.50DL, 0.75DL, 1.0DL (10–60 min hold) with displacement checks |
| Documentation | Record gauge pressures, calculated loads, and lift/deflection for each pier |
Engineering Notes
- Allowable working load uses FS ≈ 1.3 on 40‑ton ultimate; soil-controlled capacity is confirmed by hydraulic proof‑load and lift observation (pressure × ram area).
- Because FM‑PP25 is end‑bearing at refusal with no helix plates, capacity is verified by measured load rather than empirical torque correlation. See AC358 torque method for helical piles (AC358 Eq‑8).
- Helical pile published upper‑bound shaft capacities (e.g., 3½″ shafts reported up to ~98,000 lb ultimate) are contingent on meeting torque criteria, helix configuration, and foundation/bracket limits per ICC‑ES reports and manufacturer tables (ICC‑ES ESR‑1854; Ram Jack Product Table). In practice, bracket capacity and footing concrete often govern before reaching those theoretical limits.
- Retrofit helical systems typically rely on a bracket anchored to the footing. Achieving bracket contact may require removing footing overhang to reach reinforcing steel for anchorage; this introduces demolition and potential concrete damage risk. FM‑PP25 uses a compact head plate (12×6×½ A36) with direct load transfer after proof‑lifting.
- Helical compression capacities increase with larger helix diameters and shaft sizes; reaching very high loads commonly requires multiple large helices (e.g., ≥24″) and large shafts. Manufacturer tech literature and AC358 require verifying torque‑to‑capacity correlations and may still require load testing for acceptance (Torque–capacity background).
- Push pier proof‑testing is performed with the retrofit bracket/plate in place, using incremental holds and displacement checks (proof‑test procedure example).
- Foundation Masters Guarantee: We guarantee lift with FM‑PP25 under our engineered installation and proof‑testing protocol.*
*Lift guarantee administered per contract terms, access conditions, and structural safety requirements.
FM-PP25 PushPier™ vs. Ram Jack Helical Piles
Side-by-side comparison of hydraulically driven resistance piers and ICC-ES recognized helical piles used for foundation repair and retrofit.
| Specification | FM-PP25 PushPier™ | Ram Jack Helical Piles |
|---|---|---|
| Ultimate / Allowable Capacity | 40 tons ultimate; 30 tons allowable (working) | Manufacturer literature cites upper‑bound values up to ~98,000 lb ultimate for some 3½″ shafts; actual usable capacity often governed by torque achieved, helix size/number, and bracket/footing limits (ESR‑1854). |
| Corrosion Protection | Bare • Epoxy • Hot-dip galvanized | Polymer coating (e.g., PPA 571ES) or galvanization per ESR/AC228 |
| Noise / Vibration | Low noise; minimal vibration | Low noise; minimal vibration |
| Code / Evaluation | Proof-tested per pier; engineering submittals as required | ICC-ES ESR-1854 (AC358) helical systems; documented torque/length criteria |
| Best Use Cases | Underpinning where structure provides reaction and access is limited | Compression/tension applications; new or retrofit where torque verification preferred |
| Foundation Interface | FM-PP25 PushPier™ | Ram Jack Helical Piles |
|---|---|---|
| Footing Prep / Bracket | Compact plate (12×6×½ A36); direct bearing under center of footer, controlled proof‑lift. | Bracket bears on footing; may require chipping footing overhang to access steel and set anchors; demolition and patching common. |
Performance Takeaway: FM-PP25 delivers measured working capacity at refusal via hydraulic proof-loading, while Ram Jack helicals correlate capacity to installation torque and embedment. Selection depends on access, soils, and whether compression-only or tension loads are anticipated.
FM-PP25 PushPier™ System – Frequently Asked Questions
What is a Push Pier?
A push pier—also known as a resistance pier or hydraulic underpinning pier—is a steel foundation support that’s hydraulically driven into stable bearing strata beneath a structure. The FM-PP25 PushPier™ System transfers the building’s load from unstable soil to competent material at depth, restoring foundation stability and, when appropriate, structural elevation.
How does the FM-PP25 PushPier™ differ from a helical pier?
Helical piles rely on screw-like helices advanced by torque, while push piers are straight steel shafts hydraulically pushed to refusal using the structure’s own weight as resistance. Because capacity is verified by hydraulic pressure and actual lift, FM-PP25 PushPiers™ provide a direct, measurable load path without relying on empirical torque-to-capacity correlations.
Where can Push Piers be used?
FM-PP25 PushPiers™ are ideal for homes or commercial buildings experiencing settlement, cracked walls, uneven slabs, or sinking foundations. They’re especially useful in limited-access areas, under interior slabs, and along perimeter footings where heavy equipment can’t reach. Applications include underpinning, structural lift, load transfer, and retrofit foundation support.
How is pier capacity verified during installation?
Each FM-PP25 pier is proof-tested on site by measuring hydraulic pressure at incremental load stages. Once the gauge reading and displacement confirm lift, the design working load (typically 30 tons per pier) is established and documented in the installation report.
What materials are used in the FM-PP25 PushPier™ System?
Every pier is constructed from 3½″ Schedule 40 ASTM A53 Grade B steel tubing with a 12″ × 6″ × ½″ A36 top plate. Optional corrosion protection includes epoxy coating or hot-dip galvanization for long-term durability in aggressive soil environments.
Will Push Piers lift my foundation back to level?
Yes—when soil and structural conditions allow, controlled hydraulic lifting is performed during installation. FoundationMasters’ engineers verify lift with real-time monitoring to ensure safety, minimize stress, and achieve maximum practical recovery without overloading the structure.
How long do Push Piers last?
Properly installed and protected FM-PP25 PushPiers™ are a permanent foundation repair solution. Each system includes a lifetime transferable warranty, offering long-term peace of mind and structural assurance.
Why choose Foundation Masters for Push Pier installation?
FoundationMasters is a full-service structural and geotechnical engineering firm specializing in foundation repair, underpinning, and structural stabilization across Florida. Every FM-PP25 installation is engineered, inspected, and guaranteed for performance and lift verification.