Mudjacking – Raise Those Settled Slabs

Mudjacking – Raise Those Settled Slabs


Mudjacking is a process by which concrete slabs or “flatwork” (driveways, sidewalks, basement floors) are raised after settling.

Settling flatwork is extremely common throughout the front range. A safety concern with settled flatwork is tripping hazards. This occurs when adjacent slabs settle at different rates resulting in one slab being higher than the other. In the dark or in the middle of the day it’s possible to kick this small deviation in the surface and stub a toe or trip and fall.

Other problems arise if the flatwork is sloping toward the building. In this case water runs toward the home instead of away from it. This can be problematic because water next to a foundation can eventually seep into the home or cause the foundation to settle and possibly become structurally unsound.

One solution to settled flatwork is to remove the existing surface and replace it. This can be a costly endeavor. First the old slab needs to be removed – broken up, loaded up, hauled away, and then dumped. Next the surface would need to be prepared for a new slab. Finally the new slab needs to be poured. The cost of this solution, for a two-car wide driveway, can run around $2600-$3400.

Mudjacking may be a more affordable alternative solution. Small holes are drilled in the existing slab and a mud slurry is pumped into the holes and under the existing slab. This fills any voids under the slab and eventually raises the slab so that it’s even with adjacent surfaces or provides a positive slope away from the structure. A typical minimum cost for this service is around $300 with the average mudjacking job costing around $600, a much more cost effective solution than replacement.

While mudjacking can solve settling problems it should not be used as a solution for raised flatwork. Raised flatwork occurs when there is expansive soil under the concrete slab. When water seeps under the slab the soil expands and raises the slab above it. The only solution to raised flatwork is replacement. Determining the difference between raised and settled flatwork can  be tricky.  Don’t try to do it yourself. Rely on the expertise of your home inspector or concrete specialist for this analysis.

Another problem that mudjacking won’t solve is a slab with many cracks in it. Trying to fix a slab with lots of cracks is like trying to walk on boards that are floating on water. Good luck!

Finally you might wonder if mudjacking is a permanent solution. The answer is: many times yes, and sometimes no. Sometimes the slab will continue to settle and additional mudjacking will be necessary at a later date. The best thing you can do to make mudjacking a permanent solution is to make sure the cause of the settling is addressed. Causes like a gutter downspout spilling water at the edge of the concrete slab should be corrected. If you don’t re-route the downspout to direct the water away from the slab your problem will come back, guaranteed. If the cause is due to backfill from the construction process continuing to settle, you may just have to re-mudjack it. Still it’s less expensive than replacement.

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