Void Filling Under Warehouse Concrete Floors

A warehouse slab can look perfectly intact on the surface while the soil that supports it has quietly washed away underneath. Voids form when groundwater, a leaking utility line, poorly graded stormwater, or decades of vibration erode the substrate — and a slab with empty space beneath it is a slab on the verge of failure. Filling those voids is often more important than anything visible from above, because without a supportive subgrade, no amount of surface repair will hold.

Advance Concrete Lifting and Leveling is the Atlanta metro’s specialist in subsurface void remediation, and the material driving that specialization has transformed this category of work — high-density polyurethane foam, applied through the proprietary FILLFOAM™ process. Trusted by Georgia Institute of Technology, the Southern Regional Education Board, Forsyth County, Emory Hospital, and warehouse operators across the region, our team has filled voids beneath floors ranging from small commercial facilities to major distribution centers, and every project is backed by a written warranty.

Expertise in Subsurface Void Detection and Remediation

Voids beneath warehouse slabs are rarely visible until something fails. Senior technicians use a combination of acoustic sounding, visual inspection of control joint separations, and precision laser measurement to map the full extent of underground cavities before any injection begins. Knowing the size and shape of a void is essential — it determines foam volume, injection points, and cure sequencing.

“Void filling isn’t just pumping material into a hole,” says Micah Ray, President of Advance Concrete Lifting and Leveling. “Our FILLFOAM injections expand to completely fill the cavity, bond to the surrounding soil, and resist water infiltration going forward. That last part matters — most voids formed because water got in, so your fill material had better be waterproof.”

How Voids Form Under Warehouse Floors

Understanding the cause is essential to a lasting repair. The most common drivers of void formation in Georgia warehouses include:

Underground Water Line Leaks: slow leaks that wash fine soil particles away over months or years, leaving increasingly large cavities.
Storm Drainage Failures: blocked or broken storm lines that redirect water beneath the slab instead of away from it.
Poor Original Compaction: fill soils that settle unevenly years after construction, leaving pockets of unsupported concrete.
Clay Soil Shrinkage: Georgia red clay contracting in drought conditions and pulling away from the underside of the slab.
Vibration from Heavy Equipment: long-term loading from forklifts, presses, and compressors gradually densifying soil in some areas while leaving voids in others.
Buried Organics or Root Decay: decomposing organic material left during construction creating voids as it breaks down.
Why FILLFOAM™ Outperforms Traditional Void Fill

Traditional void fill methods — gravel, flowable fill, cement slurry — all have significant drawbacks in a warehouse environment. Gravel settles and washes out, flowable fill cures slowly and adds weight that can accelerate surrounding settlement, and slurry shrinks as it dries. Polyurethane foam solves all three issues: it expands rather than settles, it cures in minutes rather than days, and it is roughly one-tenth the weight of cementitious alternatives. The foam is also closed-cell and hydrophobic, which means it will not absorb water or break down in a wet subgrade.

The Void Filling Process

Crews begin with a site evaluation to locate voids and identify probable causes. Small injection ports — typically 5/8 inch in diameter — are drilled through the slab at mapped intervals. High-density polyurethane is injected in controlled volumes, expanding to fill the cavity, bond with surrounding soil, and provide full load-bearing support. Cure time is 15 to 30 minutes, and the injection ports are patched flush with the surrounding slab. Warehouse operations can resume immediately.

Frequently Asked Questions About Warehouse Floor Void Filling

How do you know where the voids are without demolition? Technicians use acoustic sounding, visual inspection of joint separations, laser measurement of slab deflection, and knowledge of typical failure patterns to map void locations. In cases requiring more detail, ground-penetrating radar is available.

Will polyurethane foam hold up under heavy forklift and racking loads? Yes. The foam is engineered for high-load applications and provides compressive strength well beyond what warehouse loading requires. Once cured, it performs as a stable, load-bearing substrate.

What happens if we do not fill the voids? Voids always worsen over time. As soil continues to erode, the slab eventually fails in some combination of cracking, rocking, and settlement. Void filling is a preventative measure that protects the slab long before visible damage appears.

Can you fill voids around utilities and under rack footings? Yes. The injection process is precise enough to work around underground utilities, rack anchor points, drainage features, and expansion joints without disturbing them.

Does the foam contaminate soil or groundwater? No. Polyurethane foam is inert once cured, non-toxic, and does not leach. It is widely used in DOT infrastructure, municipal water projects, and environmentally sensitive sites.

How does FILLFOAM™ differ from standard polyurethane void fill? FILLFOAM is a higher-density formulation engineered specifically for larger-volume void applications. It provides greater load capacity, improved soil bonding, and longer service life than general-purpose foams.

Why Commercial Operators Choose Advance Concrete Lifting and Leveling

Proprietary FILLFOAM™ Process: engineered specifically for warehouse void applications and backed by decades of field performance.

Subsurface Expertise: trained technicians who diagnose root causes rather than just treating symptoms.
Non-Destructive Approach: repairs executed through small ports, not demolition or slab replacement.
Institutional Credentials: trusted by Georgia Institute of Technology, Emory Hospital, Forsyth County, and the Southern Regional Education Board.
Comprehensive Warranty: every project documented and backed by a written warranty on materials and workmanship.
Fast Turnaround: most warehouse void fill projects completed in a single day with no operational shutdown required.

Schedule Void Fill Service in Alpharetta and Atlanta, GA

If joint separation, water pooling, slab rocking, or unexplained cracks have started showing up in your warehouse floor, voids beneath the slab are the likely cause. Call Advance Concrete Lifting and Leveling at (678) 235-9322 in Alpharetta or (404) 260-1599 in Atlanta to schedule a free on-site assessment with a senior technician. We provide void filling services throughout the greater Atlanta metro, including Alpharetta, Roswell, Marietta, Duluth, Cumming, Gainesville, and the entire north Georgia corridor.