Concrete Lifting

Water is the usual culprit. A downspout that discharges beside a driveway, a gutter that overflows at one corner, or a broken drain line will wash fines out of the soil and leave a cavity. The slab spans it for a while, then drops.

The second cause is poor compaction at build time. Backfill around a foundation, a trench cut for a utility line, or fill brought in to level a lot will keep settling for years if it was never properly compacted. Slabs poured over that fill go down with it.

The third is simply time and traffic. Repeated loading, freeze and thaw cycles, and tree roots all move soil. On a Middle Tennessee lot with clay subsoil, seasonal swelling and shrinking does the same work more slowly.

• Driveways and aprons, especially the slab where the drive meets the garage
• Garage floors that have dropped away from the foundation wall
• Sidewalks and walkways with a lip that catches a toe
• Patios and porch slabs that now tilt back toward the house
• Steps and stoops that have pulled away from the entry
• Shop and barn floors on the same properties we insulate
• Pool decking where a section has dropped below the coping

We inject polyurethane instead. The ports are about the diameter of a pencil, the foam expands in place to fill the void and compact loose soil, and it is a fraction of the weight of a slurry. It does not absorb water, so it is not washed out by the same drainage problem that caused the original void, and it cures in minutes rather than curing over days.

It is the same family of chemistry we spray into buildings every working day, which is why this service sits alongside our insulation work rather than being something we subcontract.

We mark and drill the injection ports, inject in a planned sequence while watching the slab with a level, and stop when it is back where it belongs. The ports are patched as we go. Because the foam cures quickly, you can usually walk on the surface the same day and drive on a driveway far sooner than a replacement slab would allow.

Nothing gets torn out, so there is no demolition, no skip in the driveway, and no waiting on a concrete pour and cure. Your existing slab stays, including whatever finish or colour is on it.

Concrete that is badly spalled, crumbling, or broken into many small pieces has lost its structural integrity, and lifting it just produces a level pile of broken concrete. A slab cracked into two or three sound pieces is usually fine to lift. One cracked into a dozen is usually a replacement.

We also look at the drainage before quoting. If a downspout or a grading problem is actively washing soil out from under the slab, that gets addressed too, or the void simply reopens. Raising the slab without fixing the water is a repair with a short life, and we would rather tell you that at the estimate than come back to it.

The honest answer is that we measure the slab and look at what caused the drop. What we can say generally is that lifting is usually a good deal less than tearing out and repouring the same area, and it is far quicker. We put the scope and the price in writing after we have seen it, and the visit costs nothing.

A lot of this work comes from properties we already know, because a driveway that has dropped and a crawl space that is damp often share one cause: water going where it should not. Our crawl space encapsulation page covers the inside half of that problem.