Lift the slab foundation, fill the void, keep the house where it was built.

Concrete does not sink through soil; it drops into space the soil left behind. In the clay dominated inland valleys, drought years shrink the ground and it never quite swells back to the same shape, leaving thin gaps under slab sections. In sandier coastal and desert ground, water is the sculptor: a season of poor drainage or a leaking line carries fine particles away grain by grain. Fill that was never compacted properly simply keeps compressing for decades under the slab's weight.

However the void forms, the slab bridges it silently for a while, because concrete is strong when supported and weak in bending. Eventually the span cracks or the section tips, and you get the symptoms upstairs: a slope you can feel, a lip at a slab joint, grout lines opening along one path. The lesson built into that sequence is that lifting the slab is only half the job. The other half is knowing why the void formed, so the fix does not simply refill a process that is still running.

The two problems feel identical underfoot and need opposite repairs, so the evaluation exists to separate them. A specialist maps floor elevations across the slab with a manometer, reading how each area sits to fractions of an inch, then compares the low zones to the crack pattern, the drainage picture, and the age and history of the movement. A shallow void shows up as a local low spot with stable surroundings. Foundation settlement shows up as a broader tilt that involves the footings, and it usually brings wall cracks and racking doors, doors twisted out of square in their frames, with it.

You get the measurements and the conclusion in writing. If the readings say the whole structure is settling, we will tell you slab jacking is the wrong tool before you spend anything on it, because foam under a sinking footing just goes along for the ride.

The crew drills holes about the diameter of a coin through the slab in a planned pattern over the settled area and threads injection ports into them. Two liquid components mix at the nozzle and begin expanding within seconds, flowing into the void while still liquid, compacting loose soil outward, and filling the space completely. Once the void is full, continued injection has nowhere to push but up, and the slab rises in small controlled stages while the crew watches elevations with instruments and stops at grade.

The foam reaches most of its strength in minutes, so driveways, garage floors, and interior slabs are typically back in normal service the same day. The ports come out, the holes are patched flush, and the visible evidence of the repair is a handful of small circles.

Slabs can be lifted two ways: modern polyurethane lifting or traditional mud jacking, which pumps a cement slurry. The slurry method cures into a dense base, but it is heavy, which matters when the soil below is already struggling, and it needs larger holes and cure time before the slab returns to service. Polyurethane weighs a small fraction of slurry, travels farther into a void, resists water instead of eroding in it, and carries the same day return to service.

That is why Dalinghaus lifts slabs with polyurethane and does not use mudjacking. The evaluation then decides whether a foam lift is the right repair for your slab at all, or whether the readings point to piers instead.

Slab jacking corrects slabs that dropped over shallow voids. It does not fix a foundation that is settling, a slab shattered past lifting, or ground that a live plumbing leak is still washing away. Foundation wide settlement calls for steel slab piers or perimeter underpinning that carry the structure to load bearing strata; a leak calls for a plumber before any lifting; and a slab broken into small sections may need replacement rather than rescue.

This is why the elevation survey comes first. When the numbers support slab jacking, it is one of the fastest, least invasive repairs we do. When they do not, you will see the readings that make the case for something else, instead of paying for the quick option twice.