Cracked or sunken concrete in the Phoenix metro can often be lifted, sealed, patched or resurfaced. Most local slab movement traces back to water, such as irrigation at the edges, flood irrigation or monsoon runoff, so the fix should address the source. Badly broken slabs or slabs pushed upward by swelling soil are usually better replaced.
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Not every cracked or sunken slab needs to be torn out. Depending on why it moved, concrete can often be lifted, sealed, patched or resurfaced. Around Phoenix, the cause is usually water reaching the soil under the slab, so a good repair plan includes fixing the water problem too.
Why concrete cracks and sinks in the Valley
- Irrigation next to slabs. Drip emitters, sprinklers and leaking lines can soak the soil under slab edges for years.
- Flood irrigation. In older neighborhoods that receive irrigation water from SRP, yards are periodically flooded. Slabs and walks near those yards can be affected if water gets under them.
- Moisture-sensitive soil. Some Valley clays swell when wet and shrink when dry, and some loose desert soils can settle when they get wet after being dry for a long time. Either can lift or drop a slab.
- Loose fill. Soil placed around new homes during construction, especially near garages and patios, may not have been compacted well.
- Monsoon runoff. Short, intense storms can wash soil from under slab edges and along side yards.
- Shrinkage and heat. Concrete that dried too fast during a hot pour, or has joints too far apart, can crack early.
Repair options
- Slab lifting with cement slurry (mudjacking): material is pumped through drilled holes to raise a sunken slab and fill voids.
- Polyurethane foam lifting: expanding foam is injected through smaller holes. It's lighter and cures quickly.
- Crack and joint sealing: flexible sealants keep water and dust out and help protect the base.
- Patching: repair mortars for spalled or broken spots, though color rarely matches.
- Resurfacing: a thin cement-based overlay for a worn but stable slab.
- Section replacement: badly broken panels cut out at the joints and repoured.
When lifting makes sense
Lifting usually works best when a slab is mostly intact, sank as one piece, and the soil has stopped moving. If the cause is ongoing, such as a leaking irrigation line or water ponding against the edge, fix that first, or the slab may move again. Slabs that are lifting up rather than sinking, which can happen on swelling clay, generally aren't candidates for lifting and may need to be replaced.
Trip hazards
A raised edge on a walk or driveway is a common cause of falls. Contractors can lift the low side, grind the high edge, or replace the panel. For public sidewalks, check with your city first about responsibility and permits.
When it might be structural
Most Phoenix-area homes sit on slab-on-grade foundations. Cracks in a driveway or patio are rarely structural, but cracks in the house slab or stem walls, cracks in stucco that keep growing, or doors that suddenly stick can signal foundation movement. Start with a structural engineer or foundation specialist, since that work typically needs permits and appropriately licensed contractors.
Questions to ask
- What do you think caused this, and does your plan address it?
- Will you lift, patch or replace, and why?
- How will the drill holes or patches look afterward?
- Is there a warranty if the slab settles again?
For more help deciding, read our guide to Arizona contractor licensing and permits, or mark your request urgent and request a concrete repair contractor.
See how it works
Frequently asked questions
Can a slab that rose up be lowered?
Generally not. Lifting methods raise sunken slabs. A slab heaved by swelling soil or roots is usually ground down at the edge or replaced, after fixing whatever is wetting the soil.
Is mudjacking or foam lifting better?
Both can lift intact sunken slabs. Cement slurry is a long-established method; polyurethane foam uses smaller holes, weighs less and cures quickly. The right choice depends on the slab, the voids and the contractor's experience.
Are cracks in my driveway a foundation problem?
Usually not. Driveway and patio cracks are rarely structural. Cracks in the house slab or stem walls, growing stucco cracks or sticking doors and windows are worth a structural engineer's evaluation.
Sources and further reading
- American Concrete Institute (ACI)
- Portland Cement Association (PCA)
- University of Arizona Cooperative Extension: Managing Caliche in the Home Yard (AZ1281)
- ASCE study: residential foundations and expansive clay in the Phoenix Valley
- Arizona Registrar of Contractors (ROC)
- Arizona Revised Statutes 32-1121 (contractor license exemptions)
- Arizona Administrative Code R4-9-103: residential license classifications
- City of Phoenix: Driveway Policy for Single Family Development
- City of Phoenix Street Transportation: special permits
- City of Scottsdale: Environmentally Sensitive Lands Ordinance
- SRP: residential irrigation basics
- Arizona 811: call before you dig