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Interior Slab Leveling: Fixing Sunken Floors Inside the Home
Sunken rooms, tripping thresholds, and furniture that never sits level often mean a slab has dropped — and interior slab leveling can lift it back without tearing your home apart.
Interior concrete slab leveling raises a sunken slab floor by injecting foam or cement slurry through small holes drilled in the floor. The material fills voids underneath, compacts loose soil, and gently lifts the concrete back toward level, usually in a day or two, without removing the slab or moving out.
A floor that slopes toward the middle of a room, a doorway threshold that has become a trip hazard, or tile cracked along one line are all signs Shreveport homeowners know well. Our expansive clay soil swells when wet and shrinks when dry, and when it shrinks unevenly beneath a slab, one section of floor drops while the rest stays put. This guide explains how interior slab leveling works, what it can and cannot fix, what to expect on job day, and when a sunken floor signals a deeper foundation problem.
Why Interior Slabs Sink in Shreveport Homes
A concrete slab does not sink on its own. It sinks because what is underneath it changes. In Shreveport, the usual culprit is the soil: northwest Louisiana sits on expansive clay that absorbs water and swells, then dries and shrinks. When one part of the ground under a slab dries faster than the rest — under a large tree, beside a leaky condensate line, or where a downspout used to dump water — that section of clay contracts, a void opens, and the concrete drops into it. The drop is rarely dramatic at first: a quarter inch here, half an inch there, enough to make a door drag or a rolling chair drift to one side of the room.
Other causes are just as common. A plumbing leak under the slab can wash fine soil out from beneath the concrete over months, leaving a hollow that eventually gives way. Poor compaction when the home was built can leave soft spots that settle under the slab’s own weight over the years. And in older Shreveport homes, from the brick ranches of Broadmoor to the post-war houses around Queensborough and the newer subdivisions of Bossier City, decades of wet and dry cycles have simply done their work. The pattern to watch is a floor that drops in one area while the rest of the house stays put — that localized drop is the signature of a slab problem, not whole-house settlement.
Signs your interior slab needs leveling
- Floors that slope or feel uneven. A ball or rolling chair that always ends up in the same corner is telling you something.
- Cracked tile or grout lines. Tile is rigid, so it cracks when the slab beneath it moves, often in a straight line across the dropped section.
- Doors that stick or swing on their own. A dropped slab changes door frame geometry, so interior doors drag or refuse to latch.
- Gaps at baseboards or thresholds. A baseboard pulling away from the floor, or a threshold turned into a raised lip, marks where the slab has fallen.
- Water pooling in one spot. A low area collects mop water, spills, and condensation, showing up as a damp patch that never quite dries.
How Interior Slab Leveling Works
Interior slab leveling, sometimes called slab jacking or foam jacking, follows a straightforward sequence. First, the crew maps the low areas with a level or laser, marking exactly where the slab has dropped and by how much. That map decides where the injection holes go: usually a grid across the sunken section, with holes spaced a few feet apart. The holes are small — about coin-sized for foam injection, somewhat larger for cement slurry — and they are drilled through the slab, not through the walls or the footing.
Next, the leveling material is pumped through the holes in a controlled sequence, starting at the lowest point. Polyurethane foam expands as it is injected, filling voids and compacting loose soil, and the pressure gently lifts the concrete. Cement slurry, the traditional mudjacking material, works the same way with a heavier, denser fill. The crew watches the floor rise in real time with a level, stopping at the target elevation rather than over-lifting: a slab pushed too high creates a hump that is harder to fix than the original dip, so a careful crew lifts in small increments and checks constantly.
Once the slab is level, the holes are patched with a cement compound and finished to blend with the surrounding floor. On bare concrete the patches are visible up close but unobtrusive; under carpet, laminate, or tile being replaced anyway, they disappear entirely. Most rooms are usable again the same day, and furniture can usually go back within a day or two, once the patches have cured.
Foam vs Slurry: Which Material for Inside the House
Both materials lift slabs, but inside a home the differences matter more than they do on a driveway. Polyurethane foam is lighter, expands to fill voids completely, and cures quickly, so the room can be used sooner and the added weight on the soil is minimal. Its small injection holes also mean less patching afterward, a real advantage on finished tile or stained concrete. The trade-off is cost: foam typically costs more per job than slurry, and it is less forgiving if the crew misjudges the lift, since it sets fast.
Cement slurry, the mudjacking material, is heavier and cheaper, and it has lifted slabs for decades. Inside a home, its larger holes and longer curing time are the drawbacks, and its weight can be a concern on very soft or saturated soil, where the added load can cause fresh settlement. For a garage or unfinished utility room, slurry is often a perfectly good choice. For a finished living room, kitchen, or hallway where dust, curing time, and patch visibility matter, most homeowners choose foam.
| Factor | Polyurethane foam | Cement slurry (mudjacking) |
|---|---|---|
| Hole size | About coin-sized, easy to patch | Larger, more visible patching |
| Cure time | Minutes to hours, room usable same day | Hours to days before full use |
| Weight added | Very light, minimal new load on soil | Heavy, can add load on soft soil |
| Best inside use | Finished living areas, tile, kitchens | Garages, utility rooms, unfinished areas |
| Cost | Higher per job, less patching afterward | Lower per job, more finishing work |
Neither material fixes the cause on its own. Fix a plumbing leak or drainage problem first, or the slab will drop again. Any quote that ignores the cause deserves a second opinion.
What to Expect on Job Day
Interior work is messier than exterior work, so preparation matters. Furniture in the affected room needs to move out, and anything on the floor — rugs, appliances, baseboard heaters — should be cleared from the work area. A good crew protects the rest of the house with plastic sheeting and drop cloths, because drilling concrete makes dust even with a vacuum attached. Plan to keep pets in another part of the house for the day.
The job itself is noisy but contained: drilling, pumping, and level checks, repeated across the grid until the floor reads level. You can usually stay in the house, though the room itself is off limits while work is under way. Dust control is the part homeowners notice most, so ask before the job how the crew handles it — a crew that seals doorways and runs a vacuum at the drill has done interior work before. Once the holes are patched, the room needs a short cure period before furniture goes back, and the crew should walk the finished floor with you, level in hand, before they leave.
After the job, watch the room through one wet and dry cycle. A floor that stays level through Shreveport’s seasonal swing has been properly fixed. One that drops again within months usually means the cause was not addressed, and that is a warranty conversation, not a new project. Ask what the leveling warranty covers before the job starts, and get it in writing.
When Leveling Is Not Enough
Interior slab leveling fixes a slab that has dropped. It does not fix a foundation that is still moving, and knowing the difference is the most important judgment in this whole topic. Leveling is right when the problem is localized: one room dropped, the rest of the house is stable, the cause is identified and fixed, and the slab itself is sound. It is wrong when the whole house is settling, when cracks are widening across multiple rooms, or when the slab is badly broken into shifting pieces that cannot be lifted as a unit.
Warning signs that point beyond leveling include exterior brick cracks that stair-step, doors sticking throughout the house rather than in one room, and elevation readings showing a broad tilt across the whole footprint rather than a local dip. In those cases the repair may involve piers to stabilize the foundation, drainage correction to control the water driving the movement, or both, with leveling done afterward to restore the floors. A contractor who proposes leveling without measuring the whole house first is skipping the step that decides whether leveling will hold.
Cost is part of the same judgment. Leveling a single room usually costs far less than replacing a slab or installing piers — but a cheap leveling job on a moving foundation is money spent twice, once for the lift and once for the real repair. Get full-house measurements first, fix the cause, and then level. Our guide to whether a slab foundation can be repaired covers the broader decision, and our cracked slab repair guide explains how cracks and leveling decisions fit together. The Portland Cement Association publishes technical guidance on concrete slab performance at cement.org, and the LSU AgCenter covers Louisiana’s expansive clay soils at lsuagcenter.com.
Protecting a Leveled Slab
A leveled slab stays level when the soil beneath it stays stable, and stable soil is mostly a water-management job. Keep gutters clean and downspouts discharging well away from the foundation, so roof water does not saturate one section of clay. Keep the ground sloping away from the house rather than toward it, and avoid planting large trees close to the slab, since their roots dry the clay unevenly in summer. Fix plumbing leaks promptly — a slow leak under a slab can undo a leveling job quietly over months, and by the time the floor drops again the leak has done wider damage.
If your floors have dropped, start with measurements, not a guess. Book a slab foundation repair inspection, find out whether the problem is local or house-wide, and get a leveling plan that addresses the cause as well as the symptom. For the broader picture, start with our foundation repair services in Shreveport.
Frequently Asked Questions About Interior Slab Leveling
How long does interior slab leveling take?
Most single rooms take one to two days, including drilling, lifting, patching, and curing. Larger areas or multiple rooms can take longer, but the house rarely needs to be vacated.
Do I have to move out during interior slab leveling?
Usually not. The work is confined to the affected room, which is off limits during the job, but the rest of the house stays usable. Expect noise and concrete dust in the work area despite dust controls.
Will the injection holes be visible after leveling?
On bare concrete, the patched holes are visible up close but blend in over time. Under carpet, laminate, or new tile they disappear completely, which is why many homeowners time leveling with a flooring replacement.
Is foam or mudjacking better for interior floors?
Foam is usually better inside finished rooms: smaller holes, faster curing, and less weight on the soil. Slurry is a good budget option for garages and unfinished areas where patch visibility and cure time matter less.
How much does interior slab leveling cost?
Cost depends on the size of the sunken area, how far it has dropped, and which material is used. A single room generally costs far less than replacing the slab or installing piers, and a written quote after elevation measurements is the only reliable price.
Can interior slab leveling fix cracked tile floors?
Leveling fixes the slab movement that cracked the tile, but it does not repair the tile itself. Cracked tiles usually need replacing after the slab is level, so plan the flooring work for after the lift, not before.
What if my slab drops again after leveling?
A slab that drops again within months usually means the underlying cause, a leak, drainage problem, or ongoing settlement, was not fixed. That is a warranty conversation with the contractor, and the cause should be diagnosed before any re-lift.
When should I choose piers instead of slab leveling?
Choose piers when the whole house is settling, cracks are widening across several rooms, or elevation readings show a broad tilt rather than a local dip. Leveling restores a dropped room; piers stabilize a moving foundation.
Pelican Foundation Repair
6118 Fairfield Ave, Shreveport, LA 71106, USA
318-585-2003
https://foundationrepairshreveport.com/