How Polyurethane Foam Lifting Works
Polyurethane foam lifting uses a two-part expanding foam injected through small holes drilled into the concrete, typically around five-eighths of an inch in diameter. The foam expands as it cures, filling voids and lifting the slab from below. It reaches full strength within fifteen minutes, which means the surface is usable the same day.
The foam is lightweight, so it doesn’t add load to already-stressed soil. It doesn’t wash out or compress over time the way a slurry can. Because it expands to fill the exact shape of the void beneath the slab, it provides consistent support across the entire surface rather than just where the material was injected. The smaller injection holes are easier to patch and far less noticeable in the finished surface.
Where the Two Methods Differ Most
Cure time: Mudjacking requires at least 24 hours before the slab can be used. Polyurethane foam is ready in about 15 minutes, which means you’re not waiting a full day to use your driveway or patio again.
Hole size: Mudjacking requires holes up to two inches wide. Polyurethane foam requires holes roughly the diameter of a dime. Smaller holes mean less patching, and the finished surface looks closer to what it did before the work was done.
Weight: Mudjacking slurry adds 100 pounds or more per cubic foot to the soil beneath the slab. Polyurethane foam adds about two pounds per cubic foot. Less weight on already-compromised soil means less stress on the ground that caused the settling in the first place, which reduces the likelihood of the slab moving again.
Longevity: Mudjacking material can erode, compress, or wash out over time. Polyurethane foam is waterproof and holds its shape indefinitely.
Appearance: Polyurethane foam patches blend more cleanly into existing concrete. Mudjacking patches are larger and more visible.
The weight difference is worth dwelling on. One of the most common causes of slab settling is soil that has eroded or lost its ability to support load. Pumping heavy slurry into that same compromised soil doesn’t address the underlying problem and can accelerate future movement. Foam fills the void without adding meaningful weight, so the repair isn’t working against the same conditions that caused the settling to begin with.
Where Mudjacking Equipment Can’t Go, Foam Can
Polyurethane foam works on most residential concrete surfaces: driveways, sidewalks, patios, pool decks, garage floors, and interior slabs. The equipment is compact, the injection holes are small, and the material is lightweight enough to use in situations where mudjacking simply isn’t an option. Mudjacking rigs are bulky and require significant clearance to operate, which rules them out for a number of common jobs before the question of material weight even comes up.
Crawl spaces and basement floors are inaccessible to mudjacking equipment entirely. Pool decks present a different problem: the sheer weight of mudjacking slurry puts stress on the structure surrounding the pool, making it a poor fit for that application regardless of whether the equipment can reach. In both cases, polyurethane foam is the only lifting method that works without creating a new set of problems in the process.
Why SouthernDry Uses Polyurethane Foam
Polyurethane foam cures in minutes, adds almost no weight to the soil beneath the slab, and doesn’t erode, compress, or wash out over time. The injection holes are small enough that the finished surface looks nearly untouched. Because the foam expands to fill the exact shape of the void, it supports the slab consistently across its entire underside rather than just at the injection points. For a company that backs its concrete leveling work with a lifetime warranty, foam is the only method that makes that promise realistic. Mudjacking gets slabs off the ground. Polyurethane foam gets them off the ground and keeps them there.
Get a Free Estimate from SouthernDry
SouthernDry has been lifting and leveling concrete across Alabama and the surrounding region since 2004. Every job starts with a free estimate and an honest assessment of what the slab actually needs. If you have a sunken driveway, patio, pool deck, or other concrete surface, schedule your free estimate today.