How Mudjacking Works
A mudjacking contractor drills 1.5-2 inch holes through the sunken slab at strategic locations. A pump forces a slurry mixture (cement, soil, and water) through the holes under moderate pressure. The slurry fills voids beneath the slab and, as more is pumped, creates enough pressure to lift the slab.
Once the slab reaches target grade, the holes are patched. The slurry sets within 24-48 hours and the surface is usable again.
Polyurethane foam is a lighter, faster-curing alternative. Holes are smaller (5/8 inch), the two-part resin expands to fill voids, and it cures in minutes. The foam weighs a fraction of the cement slurry - reducing the load on potentially soft subgrade soil.
How Foundation Repair (Pier Installation) Works
Pier-based foundation repair addresses the cause of settling - inadequate soil bearing - by bypassing the problem soil entirely. Piers are driven or screwed through the problem soil to competent bearing at depth (typically 15-40 feet in most regions).
A bracket transfers the structure’s load through the pier to the stable bearing stratum. Hydraulic jacks at each pier location lift the settled areas toward target grade.
This is a structural solution that remains effective regardless of what the upper soil does seasonally - the structure’s load is no longer depending on that soil.
Side-by-Side Comparison
| Factor | Mudjacking | Foundation Repair (Piers) |
|---|---|---|
| Method | Fill void with slurry, lift slab | Drive piers to stable bearing depth |
| Addresses soil instability | No | Yes |
| Appropriate for clay soil | No (short-term at best) | Yes |
| Appropriate for garage/driveway | Yes | Overkill for most |
| Affects structural floor system | Should not be used alone | Yes - appropriate solution |
| Cost | $500-$3,000 | $8,000-$25,000 |
| Hole size | 1.5-2 inch | Varies; trench for perimeter |
| Cure / usable time | 24-48 hours | Immediately |
| Expected durability (stable soil) | 10-20+ years | 25-50+ years |
| Expected durability (clay soil) | 1-5 years | 25-50+ years |
| Warranty | 1-5 years typical | 25 years to lifetime |
The Cost Trap: When Mudjacking Leads to Pier Costs Anyway
The most common misuse of mudjacking is applying it to a settling home slab on expansive clay - typically because it’s dramatically cheaper ($1,500 vs. $15,000).
Here’s what typically happens:
- Year 1: Mudjacking lifts the settled area. Homeowner is satisfied.
- Year 2-3: Clay shrinks during summer drought. The mudjacked area settles again - and so does the adjacent area that wasn’t treated before.
- Year 4-5: The homeowner pays for mudjacking again - now a larger area. Or the damage has progressed enough that the structural case for piers is undeniable.
- Year 5-7: Piers are installed. The homeowner has now paid for mudjacking twice plus the piers they needed originally.
The financially optimal path in expansive clay is to go directly to pier installation. The net cost of mudjacking twice plus piering typically exceeds the cost of piering from the start.
Choosing the Right Solution
Ask yourself:
What type of soil do I have?
- Sandy, silty, or granular soil → mudjacking is viable
- Expansive clay (Texas, Oklahoma, Colorado, Southeast) → piers are the appropriate structural solution
Where is the problem?
- Driveway, garage, sidewalk, pool deck → mudjacking is appropriate and cost-effective
- Main floor of the home, especially near exterior walls → structural assessment needed; likely piers
What symptoms am I seeing?
- Sunken concrete with no other symptoms → void issue, mudjacking may work
- Sticking doors, diagonal cracks, floor slope inside the home → structural foundation issue, get a proper assessment
Has the area been mudjacked before?
- If yes and it settled again → the soil is the problem, not the void. Piers are needed.
Getting the Right Assessment
The best way to determine which approach is right for your situation is to have a foundation repair contractor (not a mudjacking-only company) assess the problem. A contractor who offers both services can assess which is genuinely appropriate - rather than defaulting to the service they happen to sell.
For slab settling on the main floor of your home, a floor level survey showing the pattern of movement, combined with knowledge of your local soil type, typically makes the answer clear.