Foundation underpinning extends part of a house’s foundation down to soil or rock that can actually carry it, using steel piers (helical or push piers) or concrete (drilled piers or mass-concrete pours). A house needs it when a section of the foundation is still settling because the ground beneath it cannot hold the load, not when it settled years ago and has since stopped. In Los Angeles, pier underpinning typically runs $10,000 to $40,000, is designed by an engineer from a soils report, needs a building permit through plan check, and usually takes four to eight weeks of engineering and permitting followed by one to three weeks of construction.
Green Design and Build is a licensed general contractor (CSLB #1110975) based in Van Nuys, repairing and building homes across Los Angeles, Orange and Ventura counties and western Riverside and San Bernardino counties. The company is led by Dekel Sofer, who has more than 16 years in residential construction. Every price on this page is a budgeting range, not a quote; the real number comes from a written proposal after a site visit and the engineer’s design. For everything we do below the floor, see our foundation repair and seismic retrofit services.
What underpinning does, and what it does not do
A conventional footing spreads the weight of a house over the soil just below it. When that soil gives way, underpinning installs new supports beside or beneath the footing, carries them down to a layer that can take the load (competent soil, or the bearing stratum) and ties the footing to them, so the load bypasses the weak ground.
Underpinning is a narrow tool. On its own it does not:
- Fix the water that caused the settlement. A soaking downspout or a leaking drain line keeps working on the rest of the house.
- Close the cracks settlement already made. Finishes are repaired separately, and lifting can open new cracks.
- Brace the house for an earthquake. Bolting the house to its foundation and bracing the cripple walls is a seismic retrofit, a different job.
- Fix sagging floors in the middle of a raised house. Sunken interior posts and girders are a cheaper leveling repair.
Does your house need underpinning? Active settlement versus settlement that stopped
The deciding question is whether the foundation is still moving. A house that settled long ago and has been stable for decades needs its doors adjusted and its cracks patched, not piers. A house whose low corner is lower this year than last year may need underpinning. In a photograph, the two look identical.
A contractor who diagnoses active settlement in fifteen minutes and quotes piers on the spot is guessing. The evidence comes from three places:
- Change over time. Doors that started sticking this year, cracks that have widened, new gaps at the ceiling.
- Measurement. A floor-elevation survey or crack monitors, read again after a few months, show whether the low point is getting lower.
- Pattern. Settlement at one corner or wall points to soil giving way there. Cracks that open in late summer and close after the rains point to clay shrinking and swelling, a moisture problem first.
Our guide to the warning signs that a foundation needs repair covers the symptoms in detail, and our overview of foundation repair options covers every fix. If the signs are ambiguous, monitoring through a wet season before committing to piers costs very little.
When underpinning is usually the right fix
- One section of the house is settling, and measurements show it is still dropping.
- A soils report confirms the footing sits on uncompacted fill, a void or soft soil that cannot carry the load.
- A hillside house has footings moving toward a descending slope.
- A slab corner dropped after a plumbing leak washed soil out from under it, and the leak has been repaired.
When something else is the better answer
- Movement has stopped: cosmetic repair of cracks, doors and finishes.
- Cracks open and close with the seasons: drainage and moisture management first.
- Interior floors sag but the perimeter is level: house leveling and post and girder replacement.
- The concrete itself is failing (crumbling unreinforced concrete, brick, a rotated stem wall): partial or full replacement.
When underpinning is planned rather than a repair
Adding a second story, or removing a load-bearing wall and landing a new beam on a single post, concentrates weight on footings sized for the original house, and the engineer may call for underpinning or new footings there. That is design, not a defect, and it is priced inside the project. Our guides to second-story addition cost, removing a load-bearing wall and room addition cost show where foundation work sits in those budgets.
The four underpinning methods
The engineer chooses between four methods based on the soils report, the weight of the house, the depth of the bearing layer and the room to work. A contractor who sells only one system tends to recommend it for every house.
Helical piers
A helical pier is a steel shaft with one or more screw-shaped plates near its tip. A hydraulic torque motor screws it into the ground, adding extension sections until it reaches the depth and installation torque the engineer specified. A bracket on the footing connects the house to the pier, and every pier produces a recorded torque reading.
They do not rely on the weight of the house, so they suit light wood houses, and the equipment fits side yards. Cobbles and rock can stop the plates. The California Building Code requires helical piles to be installed to the embedment depth and torque criteria set by a registered design professional, without exceeding the manufacturer’s rated maximum installation torque, and requires special inspection of the installation.
Push piers (resistance piers)
A push pier is steel pipe driven straight down in short sections by a hydraulic ram. The ram pushes against a bracket attached to the footing, so the house itself provides the reaction force. Sections are added until the drive pressure reaches the target, which also load-tests each pier.
That is also the limitation: a light one-story wood-frame house may lift off its footing before the pier reaches good soil. Push piers tend to suit heavier structures, and helical piers lighter ones.
Drilled concrete piers
A drilled pier (also called a cast-in-drilled-hole pier or caisson) is a hole bored with an auger and filled with a reinforcing-steel cage and concrete. Under an existing house they are placed beside the footing and tied to it with a new grade beam or cap. They are familiar on Los Angeles hillside lots, where supports must reach past loose surface soil.
The trade-off is equipment and time: a drill rig needs access, concrete has to cure before it carries load, and lifting is harder than with steel piers. In exchange, nothing in the system is proprietary.
Mass-concrete underpinning
The oldest method: pits are dug under short, alternating lengths of the footing, filled with concrete down to firm soil, and the gap to the old footing is packed with stiff dry grout, so the house is always supported.
It makes sense when firm soil is only a few feet down. It becomes slow and costly as depth increases, and it cannot lift a house.
| Method | How it goes in | Best fit | Limitations |
|---|---|---|---|
| Helical piers | Screwed in by a hydraulic torque motor to a specified depth and torque | Light wood-frame houses, tight access, soils the plates can advance through | Cobbles and rock; must be used within the system’s evaluation report |
| Push (resistance) piers | Steel pipe pushed down by a hydraulic ram using the house’s weight as the reaction | Heavier structures; a firm layer within reach | Light houses may not provide enough weight to drive the pier |
| Drilled concrete piers | Auger-drilled hole filled with reinforcing steel and concrete, tied to the footing with a grade beam or cap | Hillside lots; designs that call for new grade beams | Drill-rig access, curing time, harder to lift with |
| Mass-concrete underpinning | Pits dug under the footing in alternating sections and filled with concrete | Firm soil only a few feet down | Slow and costly as depth grows; no lift |
What an ICC-ES evaluation report tells you about a helical pier system
The building code requires helical piles to be designed and manufactured to resist installation and service loads, and manufacturers back their systems with evaluation reports from ICC Evaluation Service (ICC-ES) under acceptance criteria AC358. A report states which components are covered, what they carry, how they must be installed and inspected, and what falls outside its scope.
Three things worth knowing:
- A report is not an endorsement. ICC-ES states that its reports are not to be construed as an endorsement of the product or a recommendation for its use. The engineer still designs your job.
- The conditions of use matter. One report we reviewed, ESR-3074, requires installation by the manufacturer’s trained and certified installers, requires calculations and drawings by a registered design professional approved by the code official, and places soils with resistivity below 1,000 ohm-cm or a pH below 5.5 outside its scope.
- Los Angeles has its own supplements. Some reports carry a City of Los Angeles supplement for use under the city’s Building and Residential Codes, adding conditions such as project-specific preproduction load tests and proof testing of at least 2 percent of production piles. In the city, ask which report the system is installed under and whether its LA supplement is current.
AC358 covers helical systems. For push and drilled piers, ask how each pier’s capacity will be verified and who inspects it.
Raised foundations and slabs: what the work looks like
Raised foundations with a crawl space
Many older Los Angeles houses sit on a perimeter footing and stem wall with a crawl space. Underpinning addresses the perimeter; interior posts are handled by leveling. With the crew already in the crawl space, check whether the house is bolted to its foundation; if it is not and it qualifies, the Earthquake Brace + Bolt grant can pay toward that work.
Slab-on-grade houses
On a slab house the piers go under the thickened slab edge. If a leaking pipe under the slab washed out the soil, it has to be repaired first, or the void keeps growing. On either type, whether to lift the house back toward level, and how far, is the engineer’s call (see the FAQs below).
Expansive clay and underpinning in Southern California
Many parts of Southern California have clay soils that swell when wet and shrink as they dry. The California Building Code defines expansive soil by laboratory testing; one of its tests is an expansion index greater than 20 under ASTM D4829 (CBC Section 1803.5.3), and in areas likely to have expansive soil the building official must require soil tests. For houses, California Residential Code Section R403.1.8 sends foundations on expansive soil to the design rules in CBC Section 1808.6.
Those rules matter for underpinning because a pier in clay is pushed and pulled by the soil around it. CBC Section 1808.6.1 requires foundations that extend into or penetrate expansive soil to be designed to prevent uplift of the structure, and to resist the forces from the soil’s volume changes or be isolated from it. In practice the engineer has to account for swelling clay gripping the upper part of the pier, not only the house pressing down on it.
The bigger lesson: on clay, moisture control comes first. Steady irrigation, downspouts that discharge away from the house and grading that falls away from the foundation reduce the moisture swing that makes clay move. Underpinning is for a corner or wall that has moved further than the framing can tolerate.
Engineering, soils reports and permits in Los Angeles
Underpinning is structural work, so in the City of Los Angeles it needs a building permit, with plans approved first. LADBS states that building plans for a structural alteration must be filed and approved by the department as a Building Plan Check before any permit is issued. The Los Angeles Municipal Code requires a permit to alter or repair a building (Section 91.106.1.1), and its exemption for minor work valued at $2,500 or less does not apply when the work impacts the structural stability of a building (Section 91.106.2). Where a structural design is required, the computations must be signed by, or carry the stamp of, an engineer or architect licensed by the State of California (Section 91.106.3.3.2).
What that means for your project:
- A soils (geotechnical) report. Under CBC Section 1803.1, investigations that involve in-situ or laboratory testing or engineering calculations are conducted by a registered design professional. The report sets the depth to competent soil and the design values. On hillside lots in the City of Los Angeles, the LADBS Grading Division reviews the report, as our foundation services page explains.
- A structural design setting the method, pier locations and spacing, and the depth, torque or pressure each pier must reach.
- Plan check and permit fees. Our guide to LADBS permit costs shows how they are calculated.
- Inspection. CBC Section 1810.4.12 requires special inspection for helical piles, in addition to the city’s own building inspections.
Burbank, Glendale, Pasadena, Santa Monica, Long Beach and the cities of Orange, Ventura, Riverside and San Bernardino counties run their own building departments. They all work from the California Building Code, but submittal requirements differ, so confirm what your department wants before the engineer finalizes drawings.
The underpinning process, step by step
- Diagnosis. Map floor elevations, photograph cracks, trace the water, and confirm the house is still moving.
- Fix the cause. Repair leaks and correct drainage before or alongside the piers.
- Soils investigation. Borings or test pits establish how deep competent soil is.
- Engineering. Method, pier count, spacing and installation criteria, with stamped calculations.
- Plan check and permit. The building department reviews the drawings and issues the permit.
- Utilities and excavation. Underground lines are marked and a pit is dug at each pier.
- Pier installation. Brackets mounted, piers installed, torque or pressure logged under inspection.
- Lift or lock off. The house is raised slowly if the design calls for it, then locked to the piers.
- Backfill and final inspection. Pits are backfilled and the permit is finaled.
- Finish repairs. Doors re-hung, cracks patched and painted, drainage completed.
How long underpinning takes
| Stage | Typical time in Los Angeles |
|---|---|
| Monitoring (only when it is unclear whether the house is still moving) | Several months, ideally through a wet season |
| Soils report, engineered design and permit | 4–8 weeks |
| Construction | 1–3 weeks |
Hillside lots, plan-check corrections and wet weather stretch these numbers. Most of the calendar goes to getting the diagnosis and design right, which is the part not to rush.
What underpinning costs in Los Angeles
Pier underpinning in Los Angeles typically costs $10,000 to $40,000, including labor, materials and the permit. That is a budgeting range, not a quote. The number of piers matters more than the size of the house: a single settling corner needs far fewer piers than a long wall that is dropping along its length. The rest of the price comes from the depth to competent soil, the method and how easy the access is, the soils report and engineering, whether the house is lifted, and the walks, patios and planting that have to come out and go back at each pier.
Because underpinning is often confused with cheaper repairs, here is how it compares with the other foundation work we publish ranges for:
| Repair | Typical Los Angeles budgeting range | When it is the right answer |
|---|---|---|
| Crack injection | $500–$3,000 per area | Stable cracks, movement has stopped |
| Drainage correction | $3,000–$15,000 | Water against the foundation; seasonal clay movement |
| House leveling and pier-and-beam repair | $5,000–$25,000 | Sagging interior posts and girders in a raised house |
| Underpinning with piers | $10,000–$40,000 | Active settlement of a footing on soil that cannot carry it |
| Partial or full foundation replacement | $30,000–$100,000+ | Crumbling, unreinforced or rotated foundations |
These are typical Los Angeles budgeting ranges, not a price list or a quote. Our foundation repair cost guide breaks each one down. If a failing retaining wall below the house is part of the problem, it is priced separately; see retaining wall cost. To spread the cost, our financing options page explains the programs we offer.
Questions to ask before you sign an underpinning contract
- What is the diagnosis, and what evidence shows the house is still moving?
- Is there a soils report, and who is the engineer of record?
- Which method, how many piers, at what spacing, and to what depth, torque or drive pressure?
- For helical piers, which ICC-ES report number, and does it have a current City of Los Angeles supplement if the house is in the city?
- Is the permit included, and who arranges the special inspection? And what is being done about drainage?
- Will the house be lifted, by how much, and what happens if the target cannot be reached safely?
- Who repairs doors, windows, cracks, concrete and planting afterward, and is that in the price?
- What does the written warranty cover, and does it come from the installer, the manufacturer or both?
Before signing, verify the contractor’s license with the CSLB, and read our guide to how contractors get paid in California, which covers the legal limit on down payments and how progress payments should track the work. If you want to see the kind of foundation work we document, our Woodland Hills whole-home rebuild shows new footings formed and reinforced before the pour.
Foundation Underpinning FAQs
What is foundation underpinning?
Foundation underpinning is structural work that extends an existing footing down to deeper soil or rock that can carry the house, using helical piers, push piers, drilled concrete piers or mass-concrete pours. The footing is tied to the new supports so its load bypasses the weak soil that allowed it to settle.
How much does foundation underpinning cost in Los Angeles?
Pier underpinning in Los Angeles typically costs $10,000 to $40,000, including labor, materials and the permit. This is a budgeting range, not a quote; the number of piers, the depth to competent soil, access, engineering and any lifting move a job within that range.
Are helical piers or push piers better?
Neither is better in general. Helical piers are screwed in and do not depend on the weight of the house, so they often suit light wood-frame homes and tight access. Push piers are driven using the house’s weight as the reaction, so they tend to suit heavier structures. The engineer chooses from the soils report and the loads.
Do I need a permit and an engineer for underpinning in Los Angeles?
Yes. Underpinning alters the structure, so the City of Los Angeles requires a building permit with plans approved through plan check, and the $2,500 minor-work exemption does not apply to work that affects structural stability. Structural calculations must be signed or stamped by a California-licensed engineer or architect, and the design is normally based on a soils report.
How do I know if my foundation is still settling?
Look for change over time: doors that recently started sticking, cracks that have widened, new gaps at ceilings or trim. The reliable test is measurement, a floor-elevation survey or crack monitors read again after a few months. Settlement that stopped years ago needs cosmetic repair, not underpinning.
Can underpinning lift my house back to level?
Sometimes, partly. Steel piers can raise a settled section, but how far is the engineer’s decision, and full recovery is not guaranteed because old framing and finishes may not tolerate it. Many jobs stop further movement and recover only part of the drop, so get the lift target in writing.
Does underpinning fix expansive soil problems?
Not by itself. Clay that swells and shrinks is driven by moisture, so drainage and steady watering come first. Where a corner has moved too far, piers can be designed for expansive soil under CBC Section 1808.6, which requires foundations penetrating expansive soil to resist uplift and the forces from soil volume change.
Is underpinning the same as a seismic retrofit?
No. Underpinning supports a footing that is settling. A seismic retrofit bolts the house to its foundation and braces the cripple walls so it stays put in an earthquake. They solve different problems, though both can be done during the same visit to the crawl space.
Sources
- LADBS, Building Permits: plans for structural alterations must be approved as a Building Plan Check before a permit is issued.
- Los Angeles Municipal Code Section 91.106, Permits: permit requirement, the $2,500 exemption and its structural-stability exception, and stamped structural computations.
- 2025 California Building Code, Chapter 18, Soils and Foundations: Sections 1803.1, 1803.5.3, 1808.6, 1810.3.1.5, 1810.4.11 and 1810.4.12.
- 2025 California Residential Code, Chapter 4, Foundations: Section R403.1.8, foundations on expansive soils.
- ICC-ES Evaluation Reports Program and ICC-ES ESR-3074, an example helical pile report evaluated under AC358 with a City of Los Angeles supplement.
Code requirements change and vary by jurisdiction; confirm current requirements with your building department. Price ranges are our own. Last reviewed 10 October 2026.
Find out whether your house actually needs underpinning
We crawl the sub-area or survey the slab, photograph what we find and tell you if you are looking at a drainage fix, a leveling job, underpinning or nothing structural at all, before we write a number down. Through March 31, 2027 we are also offering a free roof and foundation inspection with a written report and photos. We work across the cities on our service areas page, or you can contact our team to describe your house.