Foundation Pier Types Compared for Slab-on-Grade Homes

The four systems at a glance

All four go under the grade beams (the thickened concrete ribs of a slab foundation) to carry the house down to firmer or more stable soil. The descriptions and failure modes below come from the Foundation Performance Association's repair committee^[1].

	Steel push pier	Helical pier	Pressed concrete pile	Drilled concrete pier
How it goes in	Steel pipe sections pressed down using the house's weight as the reaction[1]	Steel shaft with helix plates screwed in by a hydraulic motor to a target torque[1]	Precast concrete cylinders stacked and pressed in with the house's weight until the pile stops and the house starts to rise[1]	Hole drilled, rebar placed, concrete poured and vibrated; may have a bell at the base[1]
What holds it up	Side friction, unless pushed to rock or a firm layer[1]	Torque-correlated capacity at the helix plates[1][2]	Mostly side friction, some end bearing[1]	Mostly end bearing, some side friction[1]
Typical fit	Houses heavy enough to drive against	Light loads, porches, additions, or where weight is too low to push	Cost-driven slab repair in clay	Engineer-specified repairs with drilling access
Main ways it fails[1]	Not pushed to refusal; wrong angle; overloaded; not enough house weight; bracket not clamped right away; drought at shallow depth	Wrong spacing; wrong angle; not to proper torque or below the active zone; bracket anchorage slips	Not enough weight to reach depth; cracked caps; not shimmed right away (spring-back); shallow in the active zone; drought; misaligned or unreinforced segments shifting sideways	Too shallow; bad bell; poor drainage; thin cap; honeycombed concrete; loose soil at the base; gaps that let water reach deeper clay

The one thing every system shares: depth

FPA describes each system's goal the same way: get support below the active zone, the depth where soil moisture swings with the seasons^[1]. A pier that stops in the active zone moves with the clay. FPA lists "shallow piling not driven sufficiently below the moisture active zone" and drought releasing side friction "at shallow depths" as failure modes for both pressed and steel piles^[1].

So the right question for a bid is not "steel or concrete?" It is "how deep, how was depth confirmed, and will I get the record for each pier?"

Steel push piers

Steel pipe is pressed down in sections against the weight of the house^[1]. The house's weight limits how hard the crew can push. FPA warns that a house with too little weight, or a slab without enough steel in the beam, may not let the pile reach proper depth^[1]. Ask for the final installation pressure at each pier and whether each one reached refusal.

Helical piers

Helical piers are the most standardized of the four. ICC Evaluation Service, which evaluates products for building code compliance, publishes acceptance criteria AC358 for helical piles^[2]. Under AC358:

• Ultimate capacity is predicted from final installation torque times a torque factor. Allowable capacity is 0.5 times that, a factor of safety of 2^[2].
• The torque factor must be verified by full-scale field installation and load tests^[2].
• Steel is designed for corrosion loss over 50 years: 0.013 in for zinc-coated steel and 0.036 in for bare steel^[2].
• Highly corrosive soils are outside the criteria's scope. That includes soil resistivity under 1,000 ohm-cm, pH under 5.5, high organic content, sulfates over 1,000 ppm, landfills and mine waste^[2].

Myth: "Helical piers last 100 to 150 years." The code-evaluation basis is a 50-year corrosion design period^[2]. Longer claims are manufacturer projections, not part of that standard. A pier may well outlast 50 years, but nobody can promise a number beyond the design basis.

Ask for the product's ICC-ES evaluation report (ESR) number, the target torque, and the torque log for each pier.

Pressed concrete piles

Pressed piles are common for slab repair in Texas clay. FPA's structural committee publishes a full guideline for them^[3]. Key points from it:

• Reinforcement. Segments can be interconnected with a central steel bar, rod, cable or similar. Non-interconnected segments are typically less expensive^[3]. FPA's repair committee warns that unreinforced piles can shift sideways between the top segments^[1].
• Lateral loads. Segmented piles typically cannot resist significant bending, so a house on a slope may need an engineer's lateral design^[3].
• Prescriptive spacing. For lightly loaded, reinforced foundations: exterior piles at most 8 ft apart on a one-story house, and 7 ft on a two-story with brick on the first story. Interior piles at beam intersections and at most 10 ft apart along beams. Three or more stories need an engineered design^[3].
• Shim right away. FPA lists spring-back when the crew does not shim immediately after driving as a failure mode^[1].

Drilled concrete piers

A crew drills a shaft, sets rebar and pours concrete, sometimes with a bell at the bottom for more bearing area^[1]. The goal is support below the active zone^[1]. FPA publishes a separate design procedure for drilled piers in expansive soil^[4]. One clay-specific risk: gaps around the shaft from drying soil can let water reach deeper clay and heave the pier^[1].

What no pier type does

The common repair piers are not tied to the grade beams, so they cannot hold a slab down when clay swells^[1]. If your problem is heave, ask the engineer how the design handles uplift. See expansive clay soil.

Cost

This Old House listed $1,000 to $3,000 per pier as of 2026^[5]. Pier count drives the total. See foundation pier cost for more sources and regional spread.

When to call a pro

• Before choosing a pier type, get an engineer's design that names type, count, spacing and target depth or torque.
• If a bid has no depth target or per-pier records, ask for them in writing or get another bid.
• If the house rose rather than sank, have the engineer confirm piers are the right fix.
• After the work, ask for a final elevation survey and an engineer's letter.