If you’ve collected more than one proposal for foundation work, there’s a decent chance they name different kinds of piers. One says helical piles. Another says push piers. A third mentions micropiles or drilled piers. It’s natural to want someone to say which one is best.
We won’t do that from a blog, and you should be wary of anyone who does without a soil report. What we can do is give you a fair way to compare them. Each method gets its strength from a different place and is checked in the field in a different way, and the building code and product evaluations put different limits on each. Knowing those differences helps you read a proposal and ask better questions.
This post stays at the comparison level. For the full underpinning process, see our foundation underpinning page. For helical piles part by part, see what helical piers do. For whether a house needs underpinning at all, and the choice between stabilizing and lifting, see underpinning explained for homeowners.
The useful question isn’t “which pier is best?” It’s “for this soil and this house, where will the capacity come from, and how will we know it’s there?”
What all four have in common
Every method here is a deep foundation element. Each one carries building load past weak near-surface soil to material that can support it. None of them fixes drainage, stops a moving slope by itself, or repairs damaged framing. And under the California Building Code, none of them is a catalog purchase. They are designed by a registered design professional working from site-specific geotechnical information, installed to approved plans, and inspected during installation.
The City’s Guidelines for Geotechnical Reports list what a deep-foundation recommendation is expected to address: allowable vertical capacity (end bearing or skin friction), lateral resistance, pile type, minimum embedment, diameter, spacing, and construction recommendations. Where ground or slope conditions apply, the consultant must also address downdrag and reduced lateral capacity or added lateral demand under static and earthquake loading. That list is where method choice really starts.
Helical piles
How they go in. A steel shaft with one or more helix plates is screwed into the ground by applying torque. Extensions are added until the design depth or bearing layer is reached, and a bracket connects the pile to the foundation. ICC-ES evaluation reports for helical systems describe them as used both to underpin existing structures and to support new construction, carrying compression and, depending on the system, tension.
Where capacity comes from. Mostly bearing on the helix plates, plus some shaft resistance above them.
How it’s verified. The California Building Code (§1810.3.3.1.9) lets helical pile capacity be set by the least of several methods, including bearing calculations, well-documented correlations with installation torque, and load tests where required. Torque during installation is the field check. CBC §1705.9 requires continuous special inspection while helical piles go in, recording the equipment, pile dimensions, tip elevations, final depth, and final installation torque.
Worth knowing. Torque is a verification tool tied to the product evaluation and the engineer’s documents. It isn’t a homeowner calculator. Our post on what helical piers do covers that in detail.
Push piers (also called resistance piers)
How they go in. Sections of steel pipe are driven into the ground with a calibrated hydraulic ram working from a bracket anchored to the existing footing. One public ICC-ES evaluation report (ESR-4891) describes the system as hydraulically driven steel piling connected by couplers to brackets on the load-bearing foundation. It also says adjacent piers shouldn’t be pushed at the same time.
Where capacity comes from. End bearing on a firm stratum, reached by driving. The same report describes a friction-reduction collar that lets the installer load test and verify that the pier has reached firm bearing.
How it’s verified. Installation force and a proof load test at each pier, per the manufacturer’s instructions and the engineer’s design. The report notes that soil is put back only after the piers are proof load tested. Special inspection under the building code’s driven-foundation provisions covers the equipment, location and inclination, anchor bolt tightness, and compliance with the plans.
Worth knowing. ICC-ES evaluates push pier systems under acceptance criteria AC517, which covers systems used to resist axial compression loads. The City of Los Angeles supplement to one push pier report (ESR-4317) goes further: that system must not be used for new structures or to resist horizontal loads. ESR-4891 also states that the interaction between the pier and the soil is outside the report’s scope. The steel is evaluated; whether your soil can support it is a separate, site-specific engineering question.
Micropiles
How they go in. A small hole is drilled, reinforcing steel is placed, and the hole is grouted. The Caltrans Foundation Manual, drawing on the Federal Highway Administration’s micropile reference manual, defines a micropile as a small-diameter, drilled and grouted replacement pile, typically under 12 inches across and typically reinforced.
Where capacity comes from. Friction along a grouted bond zone in soil or rock. Caltrans notes that end bearing is generally neglected because the pile is so small. CBC §1810.3.10.1 says the same thing in code terms: micropiles develop capacity through a bond zone and must be grouted with steel at every section.
How it’s verified. Through the inspections and any load tests the design and the building official require. Where the alternative-system rule below applies, test data is part of what goes to the building official.
Worth knowing. Caltrans describes micropiles as causing minimal vibration and noise, workable in access-restricted spaces and low headroom, and often used to underpin existing structures. It also notes they provide little lateral resistance. And the 2025 CBC treats micropiles in Seismic Design Categories D, E, and F as an alternative system, with the design, documentation, and test data submitted to the building official for approval. Which category applies to a given house is something the engineer determines.
Drilled piers (cast-in-place)
How they go in. A hole is drilled, reinforcing is set, and the hole is filled with concrete. The City’s geotechnical guidelines group these with other deep foundations as cast-in-hole caissons and auger-cast piles.
Where capacity comes from. End bearing, skin friction, or both, depending on the design. The geotechnical recommendations also address lateral resistance.
How it’s verified. CBC §1705.8 requires special inspection of drilling with records for each element: location, plumbness, diameter, any bell, length, embedment into bedrock where applicable, the end-bearing layer, and the volume of concrete or grout placed.
Worth knowing. Drilling rigs and concrete delivery bring their own access needs. That makes site layout part of the method conversation from the start.
Side by side
| Helical piles | Push piers | Micropiles | Drilled piers | |
|---|---|---|---|---|
| Installed by | Rotating in with torque | Hydraulic ram from a footing bracket | Drilling, steel, grout | Drilling, steel, concrete |
| Capacity mainly from | Helix bearing, some shaft | End bearing on a firm layer | Grout-to-ground bond | End bearing and/or skin friction |
| Field check | Installation torque, load tests as required | Installation force and proof load test | Inspections and load tests as required | Drilling records, diameters, concrete volumes |
| Code or evaluation limits to ask about | Product evaluation scope; seismic provisions | Axial compression only in evaluated systems | Little lateral resistance; alternative system in SDC D–F | Access for drilling and concrete |
| Special inspection | Continuous (CBC §1705.9) | Driven-foundation provisions (CBC §1705.7) | Per the approved statement of special inspections | Continuous drilling records (CBC §1705.8) |
Load tests: when one proves the rest
Separate from the installation checks above, CBC §1810.3.3.1.2 requires load tests in certain cases, including when the design load for any deep foundation element is in doubt. Control test elements are tested to ASTM D1143 or D4945, with at least one in each area of uniform subsoil conditions. If a proposal mentions a load test, ask where it will be, who runs it, and what result counts as passing.
Questions to ask about any pier proposal
- What does the geotechnical report recommend, and does the proposed method match it?
- Where does capacity come from for this method in this soil, and how will it be verified at each pier?
- Is any lateral load involved, for example on a slope? If so, how does the design handle it?
- What does the special inspector record, and who hires the special inspector?
- What access does the method need, and what in the yard or house will be disturbed?
- Is the goal to stabilize in place or to lift, and how will success be measured?
Our post on questions to ask a foundation company has a broader list.
When piers aren’t the answer
Piers support a structure. They don’t stabilize a slope that is moving as a mass, and they don’t stop water from softening soil. If drainage is part of the problem, that work belongs in the plan too. If the lot is on a hillside, our hillside foundation repair page explains why slope stabilization is a separate engineering question. And if the problem is only a settled slab or walkway, concrete leveling vs structural repair covers where that line falls.
Method choice also sits inside a longer process. Our companion post on the foundation settlement repair timeline shows where design and method selection fit, between the geotechnical investigation and City permit review. For why the house moved in the first place, start with foundation settlement repair.
Cost factors, not prices
We don’t publish per-pier or project prices. Cost depends on depth to competent soil, how many supports the design calls for, the method, access (crawl clearance, slab cutting, side yards, hillside staging), testing and special inspection, whether a lift is attempted, engineering and permits, and restoration. See what drives foundation repair cost.
Next step
If a proposal names a pier method and you want a calm second look, or you haven’t gotten that far yet, we evaluate homes anywhere in La Jolla and coordinate with licensed engineers as needed for geotechnical and structural design. Request a Free Quote, or call (650) 739-6537.
Sources (accessed October 10, 2026)
- 2025 California Building Code §1705.7, §1705.8, §1705.9, §1810.3.3.1.2, §1810.3.3.1.9, §1810.3.10
- ICC-ES Evaluation Report ESR-3074, helical foundation systems (reissued July 2025)
- ICC-ES Evaluation Report ESR-4891, push pier system (reissued August 2026)
- ICC-ES Evaluation Report ESR-4317 with City of Los Angeles Supplement, push pier system
- ICC-ES Acceptance Criteria AC358 (helical pile systems) and AC517 (push pier foundation systems), as cited in the reports above
- Caltrans Foundation Manual, Chapter 13, Micropiles (October 2015), citing FHWA-NHI-05-039
- City of San Diego, Guidelines for Geotechnical Reports (2008), §6.6.2.2