Void Filling Under Concrete in Sioux Falls, SD
A hollow sound under the driveway, a slab that flexes when you step on it, a low spot that keeps coming back after every rain — those are voids, and voids are what a slab sinks into. Concrete Raising Sioux Falls fills voids under concrete with the same materials used for lifting, stabilising the slab before it drops.
Voids form when water washes soil out from under a slab: spring snowmelt, roof runoff, a broken downspout or a leaking drain. In Sioux Falls the freeze-thaw cycle opens the gaps and the meltwater carries the soil away. A void that is filled early is a cheap job; a void left alone becomes a sunken slab, a cracked slab, and eventually a replacement.
How void filling works
Small holes are drilled through the slab and material is pumped into the voids — cement slurry for large, deep voids, polyurethane foam where the voids are smaller, the soil is soft, or the slab must be usable again immediately. The fill supports the slab from below and, in foam's case, is waterproof, so the next spring's meltwater cannot wash it out again.
Void filling is often done together with a lift: the same visit that raises the slab fills the empty space underneath it. But it is also a standalone service — if the slab has not dropped yet and the void is the only problem, filling it now is the cheapest insurance a driveway ever gets.
Signs you have voids under your concrete
A hollow or drum-like sound when you tap or walk on the slab. Water disappearing into a crack or joint instead of running off. A slab that rocks or flexes underfoot. Soil or sand washing out from under the slab edge after rain. Ants or wasps nesting in the gaps under a patio. Any one of these is worth a look — send photos and we will tell you whether it is a void, and what filling it costs.
Questions
How much does void filling cost in Sioux Falls?
Void filling is priced with the lifting job when the slab needs raising, or as a standalone service when it does not — typically a few hundred dollars for a small void, more for a large washout. The exact price is a free estimate after we see the slab.
Can voids be filled without lifting the slab?
Yes — if the slab has not dropped, filling the voids stabilises it in place. That is the best-case outcome, and the reason to call when you first hear the hollow sound rather than after the slab sinks.
What causes voids under concrete in Sioux Falls?
Water, almost always: spring snowmelt, roof runoff, a downspout discharging at the slab edge, or a leaking drain. Frost heave opens the gaps; meltwater carries the soil out. Sealing the joints after filling is what keeps it from happening again.