What foundation piers do
Settlement happens when the soil right under a footing or slab cannot carry the weight of the house, because it is soft, has dried and shrunk, has been washed out or sits over a void. Piers, also called underpinning, bypass that soil and transfer the load to deeper, stronger ground. Once the piers are in, the house can be supported on them and, within limits, lifted back toward level.
The main pier types
| Type | How it is installed | Typical use |
|---|---|---|
| Steel push (resistance) piers | Steel tube sections hydraulically driven down using the weight of the house as resistance, until they reach a load-bearing layer | Heavier homes with basements or perimeter footings; deep stable layers |
| Helical piers | Steel shafts with helix plates screwed into the soil; capacity is tied to installation torque | Lighter structures, porches, additions, slabs, new loads; sites where the house is too light to drive push piers |
| Pressed concrete piers | Short precast concrete cylinders pressed into the ground one on top of another until they stop | Slab homes on expansive clay, very common in Texas |
| Drilled (poured) concrete piers | A hole is drilled and filled with reinforced concrete | Engineered projects in clay regions; new supports under beams |
Steel push piers
A bracket is attached to the footing and steel sections are driven down, one after another, with a hydraulic ram. The house acts as the counterweight. When the pier meets enough resistance, the installer records the depth and pressure, and the load is transferred to the pier. Push piers can reach considerable depth, which helps where good soil or rock lies far down. They need a structure heavy enough to push against, so they are less suited to light porches or single-story additions.
Helical piers
Helical piers are screwed in like a large screw. Their capacity is estimated from the torque needed to turn them, so the installer can verify each pier as it goes in. The International Code Council’s evaluation service adopted acceptance criteria for helical foundation systems (ICC-ES AC358) in 2007, covering brackets, shafts, helix plates and soil interaction. Some building departments set specific documentation rules; the City of Portland, for example, requires minimum installation torque values for helical piles and load-testing criteria for push piers on permit drawings.
Pressed and drilled concrete piers
Pressed concrete piers are the workhorse of slab repair in Texas. Precast concrete cylinders are pressed into the clay under the slab until they refuse to go further, then the slab is lifted and shimmed. They are usually the lowest-cost option per pier and suit shallow-to-moderate depths. Drilled concrete piers, sometimes called bell-bottom or drilled piers, are poured in place and are often specified by engineers where deep, stable support is needed in clay.
Costs compared
| Item | Published range |
|---|---|
| Piers of any common type, per pier installed (national cost guides) | $1,000 – $3,000 |
| Typical home needing about 8–10 piers (national cost guides) | $8,000 – $30,000 |
Published figures for orientation only, not quotes. The contractor you are connected with sets the price after an inspection.
In most quotes, pressed concrete piers sit at the lower end per pier and deep steel or helical piers at the higher end. What matters more than the headline price is how many piers are needed, how deep they go and what the warranty covers. See the cost guide and, for Texas prices, our Texas foundation repair cost guide.
Which pier type fits your house?
- Slab home on expansive clay (Texas, parts of Alabama and Florida): pressed concrete, steel push or drilled piers, depending on how deep stable soil lies.
- Home with a basement or deep perimeter footing (Northeast, Mid-Atlantic, Tennessee): steel push piers are common; helical piers where the load is lighter.
- Porch, stoop, chimney or addition that is pulling away: helical piers are often the practical choice.
- Karst areas with voids (Middle Tennessee, parts of Pennsylvania and Virginia): piers that reach rock, often steel, sometimes combined with grouting; an engineer should be involved.
- Pier-and-beam or crawl space home: new concrete or steel piers under the beams, plus adjustable supports. See pier & beam repair.
What happens on installation day
For exterior piers, the crew digs a small pit next to the foundation at each pier location, exposes the footing, attaches a steel bracket and drives or screws the pier down. For interior piers under a slab, they cut a hole through the floor. Once all piers reach their target, the house is lifted in small, coordinated steps while someone watches doors, cracks and a level. The piers are locked off, the pits are backfilled and the concrete or landscaping is restored. A typical home often takes a few days, longer if there are many piers or plumbing and drainage work.
Piers do not replace drainage
Piers support the part of the house they sit under, but the rest of the foundation still rests on the same soil. Good gutters, downspout extensions, soil that slopes away from the house and fixed plumbing leaks reduce movement everywhere else and protect your investment. Many warranties also expect you to maintain drainage.
Piers in regions without clay
Piers are not only a Texas repair. In the Northeast and Mid-Atlantic, push and helical piers are used under settled footings, porches and additions, and in the karst regions around Nashville and the Philadelphia suburbs they are driven to rock beneath soil that has washed into voids. The method is the same; the depth and the engineering differ.
Questions to ask every contractor
- Which pier system do you use, and why for my house?
- How many piers, where, and how deep do you expect them to go?
- Will you record the depth and pressure or torque for each pier and give me the record?
- Is an engineer involved, and is a permit required here?
- How much lift do you expect, and what happens to existing cracks, plumbing and doors?
- What does the warranty cover, and does it transfer to a buyer?
Getting two or three answers to these questions is the best way to compare offers fairly. When you call, we connect you with an independent local contractor who serves your ZIP code; see foundation piering for more on how the work is done.