A pier in a crawl space is a column that takes load from a girder and passes it to the ground through a footing. A jack post is a steel column that does the same job and can be adjusted in height. Helical piers are steel shafts with plates, screwed deeper into the soil. When a quote lists a number of piers, posts or jacks, you want to know three things about each: what holds it up, what it holds up, and how it will be adjusted later.
The three types
| Masonry or CMU pier | Adjustable steel jack post | Helical pier | |
|---|---|---|---|
| What it is | Stacked block or brick, often topped with a cap | Threaded steel column and base plate | Steel shaft with helix plates, turned into the soil |
| What it bears on | A concrete footing in the soil | A footing or concrete pad, which must be sound | Deeper soil, reached by the shaft |
| Adjustable later | Usually only by re-shimming or rebuilding | Yes, by turning the screw | Can be re-lifted, depending on the bracket |
| Typical use | Original construction and permanent replacements | Fast support under a beam, and fine height tuning | Where shallow soil is poor, or settling keeps recurring |
| Watch for | Cracked or leaning courses, undersized or missing footing | A thin pad, bare soil, rust, or a jack used as a lasting fix with no footing | Access, plumbing and the bracket that connects to the beam |
Those descriptions are general and not claims about a given product. A contractor may combine types on one house, for example masonry piers at most points and a jack where the beam needs fine tuning.
What actually decides whether a pier holds
- The footing. A pier on a poor or cracked footing, or on none, is a decoration. Mecklenburg County says a new footing has depth and bearing requirements and is inspected before concrete is placed.
- The soil. Mecklenburg County has several soil units, and the survey rates their shrink-swell behaviour from low to very high. Neighbouring lots differ, so only the parcel’s own soil map or a contractor’s inspection settles it for your house. The Charlotte soil guide lays out the county picture. Soil does not explain a given house’s problem on its own.
- Moisture. Water pooling around a footing can wash soil away or soften it. Fixing drainage often matters as much as adding a pier. See crawl space moisture.
- The beam above. A strong pier under a rotted girder does not stop the sag. Joist and girder repair covers that side.
- Spacing and load. How far apart supports can be depends on the girder, the load and the code. This page doesn’t give a spacing figure, because spacing is a design choice the contractor should justify for your house. Ask how it was worked out. Where an engineer’s seal is needed, the county says it applies to structural elements outside the prescriptive rules.
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Raising the floor
Piers and jacks are often used to lift a sagging beam. Lifting is slow and incremental. Quick lifts can crack drywall, plaster and tile, and a good contractor tells you ahead of time what may show upstairs. No contractor can promise a floor returns to perfectly level, so ask what result they expect and what they will do if movement continues.
Where piers fit in a wider repair
Most sagging floors involve supports plus something else: a damaged joist, a rotted section of girder, or a moisture problem. The sagging floors page covers how the pieces fit together, and foundation repair covers the perimeter foundation if the walls themselves are moving.
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Cost
Pier prices are bundled into repair totals rather than published per type for Charlotte. HomeGuide’s national range for structural fixes to joists or supports is $4,500–$20,000+ (structural), and Angi’s Charlotte page lists $1,500-$9,800 for a sagging floor. Different counting methods explain much of the gap, so ask each contractor how many supports they plan and what each one rests on.
Reading a quote that lists supports
A good line item for supports answers four questions. If yours doesn’t, ask.
| Question | What a clear answer sounds like |
|---|---|
| How many, and where? | A count and a sketch showing each support under the girder |
| What type? | Masonry, adjustable jack, helical or a mix, with a reason |
| What does each rest on? | A footing, pad or deeper soil, described |
| What else is in the price? | Permit, lifting the beam, repair to joists, moisture control |
If two quotes differ by several supports, the difference may come from different goals rather than different honesty. One contractor may plan to hold the sag where it is, while another plans to lift and level. Ask each one what they are aiming for.
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When supports are not the answer
Piers and jacks solve load problems. They don’t solve a rotted beam, a leaking pipe, or a perimeter wall that is moving. If the cracks are in the outside wall rather than the floor, the question is different; read foundation crack repair. If the floor feels springy but nothing sags, extra bridging or a stiffer joist may do more than another pier.
Questions about access and disruption
Crawl spaces are cramped, and the work has to be done by hand. The contractor will need clear access to the area under the girder, and may need to move insulation, a vapor barrier or equipment. Tell them if you have a dehumidifier, ductwork or a liner in place, and ask how they will protect it. Where an installation requires digging, ask where the soil goes and how disturbed areas are restored.
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Before you sign
- Get at least three written estimates and line up the support counts side by side.
- Ask for the footing details of every pier, jack or helical shaft.
- Ask who pulls the permit and whether it is in the price.
- Ask what happens if the floor moves again, and get the answer in writing.
- Pay nothing without a written contract.
Want a contractor to look at it? Call to schedule an inspection.