Structural Service
Foundation Underpinning in Sioux Falls, SD
Underpinning means extending a foundation's support downward or outward so the building's weight is carried by soil that can actually carry it. It is the correct response when the problem is the ground beneath the footing rather than the wall above it. Everything else in this category — push piers, helical piers, slab piers — is a method of underpinning.
What underpinning is for
A footing spreads the weight of a building over an area of soil. It works as long as that soil keeps its bearing capacity. When the soil consolidates, washes out, dries and shrinks, or was never adequately compacted, the footing moves down with it and the structure above cracks.
Underpinning bypasses that soil. Steel elements are installed beneath or beside the footing and taken down until they reach material that is dense enough to carry the load. A bracket then couples the footing to the pier, and the load path runs through the steel instead of through the failing soil.
The key idea is that underpinning does not repair soil. It renders the bad soil irrelevant to the load path.
The main underpinning methods
- Push piers (resistance piers) — sections of steel pipe hydraulically driven under the footing, using the building's own weight as reaction, until the driving pressure indicates a competent stratum has been reached.
- Helical piers (screw piles) — helical plates welded to a steel shaft, rotated into the ground with a hydraulic torque head. Installation torque correlates to capacity, so capacity is verified as the pier goes in.
- Slab piers — smaller-diameter piers supporting interior slab sections that have settled independently of the perimeter.
- Mass concrete underpinning — the traditional method of excavating in sequenced bays beneath a footing and filling with concrete. Rare in residential work now, but still used in specific situations.
- Micropiles — small-diameter grouted piles used where loads are high or access is very restricted. Uncommon on typical houses.
- Soil injection and compaction grouting — improving or densifying soil in place rather than bypassing it. Applicable to some specific soil conditions, not a universal alternative.
How capacity is verified
Every pier should have a documented verification of capacity, and the method depends on the pier type.
For push piers, the hydraulic pressure required to advance the pier is recorded. When that pressure reaches the target for the design load with an adequate factor of safety, and the structure begins to react rather than the pier advance, the pier is considered to have reached bearing.
For helical piers, installation torque is measured continuously and correlated with capacity using an established torque-to-capacity relationship for the shaft type. The pier is advanced until the specified torque is achieved at or below the target depth.
Ask for the installation log. A project delivered without pier-by-pier records has no evidence that the design capacity was reached.
When underpinning is the wrong answer
Underpinning is expensive, disruptive and permanent. It should not be the answer to a problem that drainage would solve.
If the elevation survey shows negligible differential movement, if the cracking is cosmetic and stable, or if the mechanism is clearly lateral soil pressure rather than settlement, piers are not the appropriate repair. Bowing walls are stabilised laterally, not underpinned.
Similarly, if the immediate cause is an active water source — a broken service line, a downspout discharging at the footing, a failed area drain — that source must be fixed regardless. Installing piers around an ongoing washout treats the effect and leaves the cause running.
How an underpinning project runs
Step 1
Survey and design
Floor elevations, crack mapping, exterior assessment and, where warranted, soil information. Pier count, spacing, type and capacity are specified — ideally by or with a structural engineer.
Step 2
Permitting
Structural work of this type generally requires a permit and inspection. Confirm who is pulling it.
Step 3
Excavation
A pit is opened at each pier location to expose the footing. Landscaping, flatwork and utilities in the way are identified and protected or removed.
Step 4
Bracket installation
A steel bracket is fitted to the underside and face of the footing to receive the pier and transfer load.
Step 5
Pier advancement
Piers are driven or torqued to the specified criterion, with pressure or torque logged for each pier.
Step 6
Load transfer and optional lift
Load is transferred to the piers in a controlled sequence. Where lift is part of the scope, hydraulic jacks recover elevation gradually and evenly across the affected section.
Step 7
Backfill and restoration
Pits are backfilled and compacted, grade is restored, and concrete or landscaping is reinstated per the contract.
Not sure what you're looking at? Get it assessed.
Describe the symptoms and send photos. You'll get an assessment of what is likely happening and what should be measured before anyone quotes a repair — across Sioux Falls and Southeastern South Dakota.
What drives the price
- Pier count and specified capacity
- Depth required to reach competent bearing material
- Push, helical or slab pier selection
- Interior versus exterior installation — interior work means slab removal and reinstatement
- Site access for equipment and spoil handling
- Engineering design and inspection fees
- Permit costs
- Whether lift is attempted and how much recovery is targeted
- Restoration scope: concrete, landscaping, irrigation, interior finishes
Cost guide
Foundation repair cost
A fuller breakdown of how this work is priced, what is usually bundled in, and what is commonly excluded from a headline number.
Read the cost guideBefore you sign anything
Questions worth asking any contractor
- What is the design load per pier, and what factor of safety are you using?
- How will capacity be verified for each pier, and will I receive the installation log?
- Who is designing this — your sales team, your in-house engineer, or an independent engineer I can contact?
- Why this pier type rather than the alternative?
- Is a permit required, and who is responsible for pulling it and scheduling inspection?
- What is included in restoration, and what is explicitly excluded?
- What is the warranty term, what does it cover, and what voids it?
Sioux Falls, SD
Underpinning for Sioux Falls homeowners
Depth to competent bearing material is lot-specific, and it is usually the single largest driver of pier cost on any given property. Two houses close together can still require noticeably different pier depths, which is why pier pricing is quoted per pier and confirmed on site.
Whether a lot was built on placed fill is worth establishing rather than assuming. Grading plans, the original build documents, or a geotechnical report answer that question; a walk-through does not.
Attached elements built on shallower footings than the main house — stoops, porch slabs, garage aprons — are the components most likely to move independently of the structure, and they are frequently addressed separately from the house itself.
See the communities we coverCommon questions
Foundation Underpinning questions
How deep do foundation piers go?
Until they reach material capable of carrying the design load, which is determined during installation rather than assumed beforehand. That can be well under ten feet on some sites and considerably deeper on others. Reputable quotes state a depth allowance and a per-foot rate for going beyond it.
Is underpinning permanent?
The steel and the load transfer are permanent. What is not automatically permanent is the absence of new problems elsewhere — an underpinned section is supported, but an adjacent section that was not underpinned is not. That is why the survey and the design scope matter.
Can underpinning be done from inside the basement?
Yes, and it sometimes has to be when exterior access is blocked by a garage, patio or property line. Interior installation requires cutting and later replacing the basement slab, and it is generally more disruptive and more expensive than exterior work.
Do I need an engineer for underpinning?
An independent structural engineer is strongly advisable. They specify the repair without selling it, which typically produces a scope that is neither under- nor over-built, and their report is documentation you keep.
Will underpinning damage my landscaping?
Exterior pier installation requires an excavation at each location, so plantings, walks and irrigation in those areas are affected. Ask specifically what will be removed, what will be reinstated, and what is your responsibility.
Related reading
Helical Piers
Torque-verified screw piles and where they outperform driven piers.
Push Piers
Resistance piers, driving criteria and structure weight requirements.
Foundation Settlement Repair
The diagnosis that determines whether underpinning is needed at all.
Structural Foundation Repair
Load path problems that go beyond the footing.
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