Modern concrete is the most abundant manufactured material on Earth, yet it’s only rated to last between 50 and 100 years.
One of the most common causes of concrete cracking, sinking, or failure is the formation of voids beneath slabs.
Voids form when the soil beneath concrete slabs is displaced or eroded over time. As moisture moves through the ground, it carries fine particles away, leaving empty pockets beneath the slab.
Without uniform support, the concrete begins to flex under weight, leading to cracks, uneven settling, and eventual sinking.
Void filling addresses this problem by stabilizing the soil beneath the slab instead of replacing the concrete entirely. In concrete lifting applications, specialized materials are injected through small holes to fill these voids, restore support, and raise the slab back to its proper elevation.
This guide will discuss the practice of void filling and several ways it can extend the lifespan of concrete and benefit NEPA property owners.
How Does Void Filling Work in NEPA
Void filling stabilizes uneven or sinking concrete slabs by injecting a stabilized material underneath the slab to fill any voids and support the weight of the slab.
The void-filling process works by injecting material directly into these empty spaces. Depending on the application, contractors use either high-density polyurethane foam or cement-based grout.
The material flows into the voids, displaces trapped air and water, and hardens to create a stable base. As the voids are filled, the slab regains structural support and can be precisely lifted back toward its original elevation.
Types of Void Filling Services
There are two processes for filling voids: polyjacking and mudjacking.
1. Polyjacking
Polyjacking uses high-density polyurethane foam injected through small holes drilled into the slab. As the foam expands, it fills voids, compacts loose soil, and gently lifts the concrete back into position.
The material cures quickly, adds minimal weight to the soil, and resists moisture intrusion, making it well-suited for the region’s variable soil and weather conditions.
2. Mudjacking
Mudjacking (also known as slabjacking) involves pumping a cement-based slurry beneath the concrete. The heavier mixture fills voids and raises the slab through hydraulic pressure.
Mudjacking is a temporary solution, only lasting 3-5 years on average. The added weight can place additional stress on already weak soils, potentially increasing the risk of future settling in some NEPA properties.
What Causes Voids Underneath Concrete?
Voids form when the soil supporting a concrete slab is displaced, weakened, or removed. Once that support is gone, the slab has nothing to rest on, which leads to cracking, settling, or sudden failure.
Several factors contribute to this issue in NEPA, including:
- Soil Erosion: Over time, soil beneath concrete surfaces can erode due to water runoff or other environmental factors, creating voids.
- Settling: The natural settling of the ground can cause voids to form beneath concrete, leading to sinking or uneven surfaces.
- Leakage or Water Intrusion: Water infiltration can wash away the soil beneath concrete, creating voids and compromising its stability.
- Pest Activity: Burrowing pests, like rodents, can create voids as they tunnel beneath concrete surfaces.
If left untreated, voids can cause concrete sidewalks to sink and become uneven, creating massive liability for property owners. Uneven concrete patios, driveways, and foundations caused by voids can lead to water pooling, further exacerbating issues and damaging your foundation.
7 Benefits of Void Filling for NEPA Property Owners
Proper void filling with high-density polyurethane foam provides long-term support, helping maintain the appearance and stability of concrete slabs on your property.
1. Structural Stability
Void filling restores the structural stability of your concrete surfaces, preventing further sinking, settling, or cracking. If using a high-density polyurethane foam, void filling can stabilize a concrete slab for decades.
2. Cost-Effective
Replacing concrete requires demolition, disposal, new materials, and extended labor. Void filling corrects the underlying issue without removal, delivering comparable structural results at a fraction of the cost.
3. Quick and Efficient
Polyurethane void filling offers quick, efficient results, curing in just a few minutes once injected.
Whereas concrete replacement could take days or weeks to complete, void filling is typically completed in a matter of hours, minimizing disruption to your daily activities.
4. Long-lasting Results
Properly executed void filling provides long-lasting results, ensuring that your concrete surfaces remain stable and even for an extended period. By some estimates, void filling can extend the lifespan of a concrete slab by up to 60 years.
5. Improved Aesthetics and Home Value
Addressing voids and unevenness enhances the aesthetics of your property, boosting curb appeal and overall visual appeal. This leads to higher property values and home equity.
6. Eco-Friendly
Modern polyurethane foams are inert, non-toxic, and require less material than full slab replacement. Less waste, less excavation, and lower resource use make void filling an environmentally responsible repair option.
7. Improved Safety
Sunken slabs create trip hazards and drainage problems. Void filling makes concrete sidewalks and driveways safer, reducing the risk of accident or injury.
How to Spot Hidden Void Problems Before Major Damage Occurs
Concrete voids cannot be spotted directly, but there are many signs that voids could be the reason for your concrete issues, including:
- Gaps between walls and slabs
- Sunken slabs
- Cracked slabs
If you notice any of these signs, it’s time to take action and support the slab with proper void-filling procedures. Voids can compound quickly, making the repair process more difficult and expensive.
Which Void Filling Solution Is Right for Me?
For most NEPA properties, polyurethane foam injection (polyjacking) is the preferred method for filling voids.
Polyfoam is lightweight, water-resistant, and expands to penetrate loose soils and hidden voids fully. This allows it to both lift and stabilize concrete without adding stress to already compromised ground. Because it cures quickly and does not absorb moisture, polyfoam performs well in NEPA’s freeze–thaw conditions and variable soil types.
Mudjacking is significantly heavier than polyfoam and can contribute to future settling in weak or erodible soils. For residential driveways, sidewalks, patios, garage floors, and interior slabs, polyjacking typically delivers longer-lasting results with less disruption.
Overall, the right solution depends on your budget, slab size, load requirements, soil conditions, and the underlying cause of settlement. A professional evaluation ensures the repair method addresses both the visible problem and the conditions beneath the concrete.
How to Prevent Voids From Coming Back
The best line of defense against concrete voids is properly directing drainage. Water and moisture wear away at soil and slabs and will continue to create voids until it’s under control.
After filling the voids properly, you should:
- Direct gutter downspouts away from the foundation
- Fix any water leaks
- Ensure drainage systems are in place to redirect water flow away from the slab
When void filling is combined with proper drainage control, concrete lifting becomes a permanent solution rather than a temporary fix.
FAQs
How do I know if void filling is necessary for my concrete surfaces?
Signs like cracks, sinking, or unevenness indicate potential voids beneath the concrete. A professional assessment can confirm the need for void filling.
Is polyurethane lifting suitable for all types of concrete surfaces?
Yes, polyurethane lifting is versatile and can be used on various concrete surfaces, including driveways, sidewalks, patios, and even foundation slabs.
How long does the void filling process take?
The duration depends on factors like the size of the project and the void filling method used. Polyurethane lifting is typically quicker compared to traditional mudjacking.
Can void filling prevent future void formation?
While void filling addresses existing issues, it’s essential to address the root causes to minimize the risk of future void formation. Proper drainage and soil management are key preventive measures.
Are there any long-term maintenance requirements after void filling?
Once void filling is complete, there are typically no extensive maintenance requirements. However, regular inspections of the concrete surfaces can help identify and address any potential issues early on.
Will void filling lift my concrete back to its original height?
Yes, professional void filling will usually bring concrete slabs back to their original height.
How much weight can polyurethane foam support?
The amount of weight polyurethane foam can support varies by the product. However, around 5,000 pounds to 10,000 pounds per cubic foot is typical.
Will the drilling holes be visible after the repair?
In most cases, the holes are barely noticeable once the repair is complete. The injection points are small and are sealed with matching material after lifting, allowing them to blend into the surrounding concrete. While minor cosmetic marks may remain, they are far less visible than cracks, sunken sections, or uneven slabs caused by untreated voids.
Can void filling be done in cold weather?
Yes, void filling can be performed in cold weather, but it requires the right materials and installation methods. High-density polyurethane foam is specifically formulated to cure and expand in lower temperatures, making it suitable for winter and early-spring projects common in NEPA. Contractors also account for ground temperature, moisture conditions, and slab thickness to ensure proper expansion and bonding.
