On site, in order
A typical residential job follows the same sequence whether the slab is a driveway, a patio or a run of sidewalk. Commercial work adds traffic control and scheduling around the people who use the space, but the steps are the same.
- Set a reference. A string line, straightedge or laser gives a fixed target so the lift is measured, not judged by eye.
- Drill the pattern. Holes go through the slab in a layout planned for the void and the slab's size. Foam ports are about 5/8 in; slurry holes are larger, roughly 1 to 2 in.
- Fill before lifting. The first material fills empty space under the slab. Until the void is full, the slab doesn't move.
- Lift in short stages. Injection continues at several holes in turn so the slab rises evenly. The crew stops and checks often.
- Patch the holes. Holes are filled with a cement-based patch and finished flush.
- Seal the joints. Open joints and cracks get a flexible sealant so surface water has a harder time reaching the subgrade.
Slabs that connect, such as a stoop and the walk below it or a garage apron and the first driveway panel, are lifted as a group. Raising one alone can pinch or crack the joint between them.
How we choose between foam and slurry
Both methods fill the void and raise the slab. They differ in weight, hole size, cure time and cost of material, and those differences decide the job. The detailed pages on polyurethane foam leveling and mudjacking in Denver cover each one in depth.
| What matters on the job | Polyurethane foam | Mudjacking slurry |
|---|---|---|
| Hole size | About 5/8 in | Roughly 1 to 2 in |
| Weight added to the soil | Very light | Heavy, cement-based |
| Ready for use | Foot traffic usually the same day | Needs more curing time before vehicles |
| Behavior in wet ground | Doesn't wash out | Can be affected if water keeps flowing under the slab |
| Material cost | Higher | Usually lower |
Soft or wet soil tends to favor foam because it adds very little load. A large, dry void under a slab with no rush to drive on it can be a reasonable slurry job. We explain the reason for our recommendation in plain terms, so you're not choosing a method blind.
After the lift
Most repeat settlement comes from the same water that caused the first one. The best thing an owner can do after any concrete leveling job is move water away from the slab.
- Extend downspouts so they discharge several feet past the edge of the concrete.
- Adjust sprinkler heads that spray onto slabs or soak the soil along their edges.
- Keep joints sealed. Check them each spring after the freeze-thaw season.
- Watch the grade along the foundation and fill low spots so water runs away from the house.
Measure first, fix the water, lift slowly, seal the joints. Every job we do follows that order, whichever material goes under the slab.
