Steel push piers, pressed concrete or drilled piers: choosing the right fix for a slab

Neither one wins for every house

Steel push piers are not automatically better than concrete piers, and concrete is not automatically the budget compromise. Pressed concrete piers are a proven, cost-effective fix for typical slab settlement on North Texas clay. Steel push piers reach deeper load-bearing strata and cost more, which makes them the better choice for heavier structures or where the stable layer is deep and the clay above it is unstable. Drilled and bell-bottom piers handle higher loads still. The right answer comes from your soil, the weight of your house and the depth to stable ground, not from a brochure.

I am a structural analyst at FCS Foundation & Concrete, and we install five pier methods for exactly this reason. A company that sells one pier type will tell you its pier is best. A company with several will tell you which one fits. This guide explains how each works, where it fits and how to judge the recommendation on your estimate.

How pressed concrete piers work

A pressed concrete pier is a stack of pre-cast concrete cylinders. The crew digs beside the slab, sets the first cylinder under the beam, and uses a hydraulic ram to press it into the ground, using the weight of the house as the counterforce. Another cylinder goes on top, and another, until the column meets enough resistance that the soil will not let it go farther. Then the slab is lifted off the top of the pier column and shimmed.

For most single-story and two-story houses on our clay, this is the workhorse repair. It is fast, the materials are relatively inexpensive, and because each pier is pressed until it refuses, the installation itself tests the bearing. Our pricing page describes pressed concrete as cost-effective for typical residential slab settlement, and in my experience it fits more Dallas houses than any other single method.

How steel push piers work

Steel push piers use the same basic idea with different material. Galvanized steel pipe sections are driven hydraulically, again against the weight of the structure, down to load-bearing strata or bedrock. Because steel sections are slimmer and stronger than concrete cylinders, they can be driven much deeper before they stop.

That depth is what you are paying for. Where the clay is deep and unstable, or the structure is heavy, a pier that reaches past the active soil to firm bearing is worth the extra cost. Our foundation repair page sums it up: steel push piers reach load-bearing strata and cost more, while pressed concrete is proven and cost-effective for many homes in the area. The deciding question is how far down the stable layer is under your house.

Steel is not a fix for a bad diagnosis, though. A deep pier under a slab that is being lifted by a plumbing leak will not stop the lift, and a steel pier at one corner will not hold a side of the house that is dropping everywhere else. The method only matters once the cause and the layout are right.

Drilled, bell-bottom and hybrid systems

Drilled piers are built in place rather than pressed. The crew drills a shaft, sets steel reinforcing bar and pours concrete. Our single-drill concrete pier is a reinforced, drilled pier used for higher loads or where the stable layer is deeper than pressed piers can practically reach. A bell-bottom pier is drilled deep and flared at the base, so it bears on a wider footprint for maximum support. We use bell-bottoms for heavy loads and for new-build support.

A hybrid system combines steel and concrete, and we customize it when the soil changes across the footprint of the house. That happens more often than people expect: a lot that was partly filled when it was graded, a house that straddles different soil, or an addition built on a different foundation than the original.

• Pressed concrete: pre-cast cylinders pressed under the home's weight; cost-effective for typical slab settlement
• Steel push piers: galvanized sections driven to load-bearing strata or bedrock; heavier structures and deep, unstable clay
• Single-drill concrete: reinforced and poured in place; higher loads or a deeper stable layer
• Bell-bottom: drilled deep and flared at the base; heavy loads and new construction
• Hybrid: steel and concrete combined where soil varies across the footprint

The four facts that decide the method

When I recommend a pier type, it comes from the elevation survey and what we know about the soil, not from a default. Four facts drive the choice, and you can ask any company to explain its recommendation in these terms.

If a recommendation does not reference at least the first two, ask why. A good estimator should be able to tell you, in a sentence or two, why a different pier would be wrong for your house.

• Depth to stable soil: shallow enough for pressed concrete, or deep enough to justify steel
• Weight of the structure: a heavy two-story or masonry house loads each pier more
• Access: tight side yards, patios and interior locations limit equipment and change the cost
• Type and severity of movement: a settled corner is a different problem from a whole side dropping, and a heave is not a pier problem at all until the water is stopped

Reading the pier line on an estimate

Most estimates reduce all of this to one line: a number of piers and a type. That line deserves a few minutes of questions before you sign, because it carries most of the cost and most of the long-term value of the repair. I would rather a homeowner ask me every one of these than wonder afterward.

Pay attention to how the answers are given, not just what they are. An estimator who knows why a method fits your house can explain it with your own readings. One who cannot is usually repeating what the company installs on every job. If you are interviewing several companies, my broader list of questions to ask a foundation repair company covers the rest of the conversation.

• Which pier type, and why it fits this soil and this house rather than another type
• How many piers, and which elevation readings put each one where it is
• Which piers are exterior and which are interior, and who restores floors over interior piers
• How the crew knows a pier has reached adequate bearing
• What the warranty says about this specific pier type

What each choice does to the price

The method changes the per-pier cost, and the per-pier cost multiplied by the count is most of your bill. Our published range is roughly $1,000 to $3,500 per pier, and our pricing page notes that steel and bell-bottom piers cost more than pressed concrete. Interior piers, whatever the type, cost more than exterior ones because floors have to be opened and restored.

That means a steel recommendation can raise a total substantially. It is worth paying for when the soil calls for it, and worth questioning when it does not. I walk through the rest of the cost picture, including why a low bid can end up costing more, in what foundation repair costs in Dallas.

Does the pier type change the warranty?

It can, so read the document rather than the brochure. Our written lifetime transferable warranty names pressed pilings, in concrete, steel and combination form, and it states its goal: to stabilize the repaired portion of the foundation to within one part in 240, about 1 inch in 20 feet. Pier-and-beam reshimming and wood repairs carry shorter transferable warranties, and concrete and drainage work carry a one-year warranty.

Whoever you hire, ask which pier types the lifetime coverage applies to, and get the answer in writing on the estimate. A warranty that covers one method and not another can quietly change the value of two bids that look similar.

Pier-and-beam houses are a different conversation

Everything above is about slab foundations. A pier-and-beam house, with a raised wood floor over a crawl space, is supported by its own piers, pads and beams, and repairing it usually means re-shimming, replacing failed piers and repairing or sistering sagging beams, often working from inside the crawl space. Many of the older homes in the area are built this way. If yours is, my guide to sagging floors in older pier-and-beam houses is the one to read.

Some houses have both. An older pier-and-beam home with a slab addition, or a slab house with a later raised room, needs a plan that treats each part on its own terms. The slab side gets piers chosen by the logic above, and the raised side gets shims, pier replacement or beam work. We repair both types with the same crews, which keeps the two halves of the house on one plan and one schedule.

Getting a recommendation that fits your house

Our evaluation is free. I take the elevation survey, look at the soil conditions and the drainage, and recommend a method and a pier count with the reasons written down. You get an itemized estimate on the spot or within 24 hours, and if you have another bid that recommends a different pier, bring it. I will tell you where I agree and where I do not, and why.

Once a method is chosen, the installation itself follows the same rhythm regardless of pier type: excavation, installation, a controlled lift, backfill and re-measurement. I describe that week day by day in what a foundation repair week looks like, so you know what to expect before the crew arrives.

Questions people ask me