Before we arrive
- Move cars off the driveway and anything heavy off the slabs we're lifting.
- Mark any sprinkler heads, invisible dog fence or low-voltage lines near the concrete.
- Keep pets inside while we're working.
- You don't need to be home. Our rig has its own power and material.
On the day, step by step
Illustrations, not to scale. Most residential jobs take a few hours, and you can walk on the slab when we pack up.
Before we leave, we check every section against the line, clean up, and text you before-and-after photos.
What's happening under the slab
A sunken slab almost always has empty space under it, where water carried soil away or loose fill settled. The foam has to fill that space before it can lift anything. That's why we inject in short shots: the first few fill the void, and the ones after that do the lifting. Stopping between shots lets the foam firm up so the slab rises in small, controlled steps instead of jumping.
Before and after
Why polyurethane foam
- Light. It weighs a few pounds per cubic foot, so it doesn't add load to the soil that already let the slab down. Mudjacking slurry weighs many times more.
- Waterproof. It doesn't absorb water or wash out like soil or slurry can.
- Fast. It reaches most of its strength in minutes.
- Small holes. About 5/8 inch, so the finished slab looks like the original concrete.
Afterward
Walk on it right away. Drive on it later the same day once the patches set. Keep downspouts pointed away from the slabs, and keep the joints sealed. Those two things do more than anything else to keep concrete where it is.