# Void Filling Under Concrete New Orleans | New Orleans Concrete Leveling

> Void filling under concrete in New Orleans: fill washed-out gaps under slabs before they crack or sink. Common near downspouts. Free estimate in 24 hours.

URL: https://concretelevelingneworleans.com/void-filling/

# Void Filling Under Concrete in New Orleans — Fix the Hollow Before the Slab Breaks

A hollow sound, a gap at the slab edge or a panel that rocks underfoot means the support has washed out. Filling it now costs less than lifting — or replacing — later.

[Call (504) 517-8336](tel:+15045178336) [Get a free estimate](#estimate)

Last updated: September 24, 2026

[New Orleans Concrete Leveling](https://concretelevelingneworleans.com/) connects property owners with independent local contractors who fill voids under concrete slabs in New Orleans — the washed-out spaces under driveways, patios, walks and slab floors — by injecting material until the slab is fully supported again. Void filling is priced by the volume of material it takes, which isn't known until the void is probed. As a reference, [HomeGuide](https://homeguide.com/costs/mudjacking-cost) lists mudjacking at **$4–$9 per square foot** and polyurethane foam at **$8–$25**, with a **$300–$700 minimum**.

A void is what comes before a sunken slab. Water finds a path under the edge — a downspout, a leaking pipe, runoff from a yard — and carries fine soil away. The slab bridges the gap for a while. Then it cracks across the unsupported span, or the edge drops. Fill the void first and you often avoid both.

## What happens on the first visit

Voids are found by sound, sight and probing. Expect the contractor to:

1.  **Tap the slab** to map hollow-sounding areas.
2.  **Look at the edges** for visible gaps, soil washing out, or erosion channels.
3.  **Trace the water source** — downspouts, grade, a leaking line, or pool plumbing.
4.  **Probe through a test hole** where needed to gauge void depth.
5.  **Recommend the fill and the water fix**, with a written price.

## Where voids form in New Orleans

The usual suspects are downspouts that empty against a slab edge, driveways and walks where yard runoff crosses at the same low spot, slabs over a leaking water or sewer line, and pool decks over leaking returns. New Orleans' rainfall — more than 60 inches a year per the [National Weather Service](https://www.weather.gov/lix/newnormals) — means there's plenty of water to do the work.

The ground itself contributes. The [City of New Orleans](https://ready.nola.gov/hazard-mitigation/hazards/subsidence/) lists ruptured water and sewer lines among the effects of subsidence, and a broken line under a slab is a void-maker.

## Filling vs lifting

If the slab hasn't moved yet, the job is simply to fill the space and stop the water. If it has dropped, the same injection that fills the void can lift it back — then it becomes a [driveway](https://concretelevelingneworleans.com/driveway-leveling/), [patio](https://concretelevelingneworleans.com/patio-porch-leveling/) or [sidewalk](https://concretelevelingneworleans.com/sidewalk-leveling/) leveling job. Filling early is cheaper because less material goes in and the slab hasn't cracked.

**[Mudjacking](https://concretelevelingneworleans.com/mudjacking/)** slurry is economical for large, open voids. **[Polyurethane foam](https://concretelevelingneworleans.com/polyurethane-foam-leveling/)** expands to fill irregular spaces, resists water once cured and adds little weight. For soft soil below the void, see [soil stabilization](https://concretelevelingneworleans.com/soil-stabilization/).

## Stop the water or the void comes back

Filling a void without fixing the water that made it only buys time. Extend or redirect downspouts at least a few feet from the slab, regrade soil so it falls away from the edge, seal the joints so surface water can't enter, and have a plumber test any line you suspect. The [will my slab sink again?](https://concretelevelingneworleans.com/guide/will-my-slab-sink-again/) guide covers the causes of repeat settling.

Not sure which method is right for your slab?

A free on-site estimate answers it — drop measured, voids checked, written price. Free estimate within 24 hours.

[(504) 517-8336](tel:+15045178336) [Estimate the cost first](https://concretelevelingneworleans.com/tools/concrete-leveling-cost-estimator/)

## How void filling is priced

Because the price follows the amount of material, contractors quote void filling after probing — sometimes with a per-unit rate for material beyond an estimated quantity. Ask how overruns are handled before work starts. Most contractors carry a $300–$700 minimum.

If a covered event such as a burst pipe caused the washout, ask your insurer; settling from ordinary drainage is generally excluded. See [does insurance cover concrete leveling?](https://concretelevelingneworleans.com/guide/does-insurance-cover-concrete-leveling/)

## What a proper void filling job includes

-   Hollow areas mapped by sound and probing
-   Water source traced and explained
-   Written price with material-overrun terms
-   Fill injected until the void is closed
-   Slab watched so it isn't over-lifted
-   Holes patched with cement grout
-   Edges and joints sealed against water
-   Downspout and drainage advice

## DIY patch vs cheapest operator vs proper void filling

| Factor | DIY patch or topping | Cheapest operator | Proper leveling job |
| --- | --- | --- | --- |
| Fixes the void under the slab | No | Sometimes | Yes |
| Actually raises the slab | No | Yes | Yes |
| Drop measured at every joint first | No | No | Yes |
| Method chosen for your soil | n/a | Whatever rig they own | Yes |
| Written price before drilling | n/a | Rarely | Yes |
| Holes patched, joints sealed | n/a | Holes only | Yes |
| Drainage cause addressed | No | No | Yes |
| Carries liability insurance | n/a | Ask | Ask — and verify |
| Typical life | Cracks as the slab keeps moving | Short if the cause isn’t fixed | 5–10+ years (mudjacking) |
| Typical cost, 150 sq ft patio | Materials only | Lowest bid | $600–$1,400 slurry · ~$1,200–$3,750 foam |

Proper-job cost and life from [HomeGuide's mudjacking cost data](https://homeguide.com/costs/mudjacking-cost); foam range calculated at HomeGuide's $8–$25/sq ft. Resurfacers and self-leveling toppings cover the surface; they don't lift the slab.

## Void Filling: related guides

-   [Local Guide Why does concrete sink in New Orleans?](https://concretelevelingneworleans.com/guide/why-new-orleans-concrete-sinks/)
-   [Learn Will my concrete sink again after leveling?](https://concretelevelingneworleans.com/guide/will-my-slab-sink-again/)

Free estimate line

[(504) 517-8336](tel:+15045178336)

Call now for a free, no-hassle quote. Estimates within 24 hours.

[Call now](tel:+15045178336)

What a good estimate records

-   Drop at each joint, in inches
-   Void locations and size
-   Method and why it was chosen
-   Drainage fix, if needed
-   Written price and timing

[Free tool Is it a leveling job? Take the 2-minute assessment →](https://concretelevelingneworleans.com/tools/concrete-leveling-assessment/)

Step by step

## How void filling works

1.  01
    
    ### Call or request an estimate
    
    Tell us where the slab sounds hollow or shows a gap. You'll hear back to set up a free estimate within 24 hours.
    
2.  02
    
    ### Map and probe
    
    The contractor maps the hollow areas, traces the water source and gives you a written price.
    
3.  03
    
    ### Fill the void
    
    Material is injected through small holes until the space is closed, with the slab watched so it isn't over-lifted.
    
4.  04
    
    ### Seal and redirect water
    
    Holes are patched, edges and joints sealed, and the water source addressed so the void doesn't return.
    

Get your slab measured and priced.

Free estimate within 24 hours. Call (504) 517-8336 or send a request.

[Call (504) 517-8336](tel:+15045178336) [Request an estimate online](https://concretelevelingneworleans.com/contact/)

FAQ

## Void Filling questions

### How do I know if there's a void under my concrete?

Common signs are a hollow sound when you tap the slab, a visible gap under the edge, soil washing out after rain, and a panel that rocks or flexes underfoot.

### How much does it cost to fill a void under a slab?

It depends on the volume of material. Contractors quote after probing; reference rates are $4–$9 per square foot for mudjacking and $8–$25 for foam, with a $300–$700 minimum.

### What happens if I don't fill a void?

The slab bridges the gap until it can't, then cracks across the unsupported area or drops at the edge. At that point it needs lifting, and severe cracking can mean replacement.

### Is foam or slurry better for filling voids?

Slurry is economical for large, open voids. Foam expands into irregular spaces, resists water once cured and adds very little weight. Many contractors choose based on void size and water exposure.

### Who does the work, and are they licensed and insured?

New Orleans Concrete Leveling is a free service that connects you with an independent local contractor. We ask every contractor we work with to carry a license and insurance — and we recommend confirming both before work begins. Louisiana requires a state license for residential jobs over $75,000 and home improvement registration from $7,500 to $75,000, so most leveling jobs fall below both — which makes insurance the check that matters. See [how to verify a Louisiana contractor](https://concretelevelingneworleans.com/guide/louisiana-contractor-license-concrete/).

## Related services

-   [Soil Stabilization Inject polyurethane into soft or washed-out soil under a slab to firm up the base before — or instead of — a lift. See how it works](https://concretelevelingneworleans.com/soil-stabilization/)
-   [Driveway Leveling Lift a sunken driveway panel back to grade and close the lip at the garage, the sidewalk or the street — without tearing it out. See how it works](https://concretelevelingneworleans.com/driveway-leveling/)
-   [Patio & Porch Leveling Fix a patio that tips back toward the house or a porch slab pulling away from the door — and stop water running at the foundation. See how it works](https://concretelevelingneworleans.com/patio-porch-leveling/)

Ready to level your slab?

Call now for a free, no-hassle quote. Estimates within 24 hours.

[Call (504) 517-8336](tel:+15045178336) [Request a free estimate](https://concretelevelingneworleans.com/contact/)