Concrete crack and joint sealing
Water getting into cracks and joints is how small concrete problems become big ones. Sealing is cheap insurance.
Concrete cracks. Control joints are cut into slabs so it cracks in planned lines, but over time joints open up, the original filler fails, and new cracks form. Every open crack and joint lets water reach the soil underneath, where it softens the base in spring and freezes in winter. Sealing them slows that cycle down.
What does crack and joint sealing involve?
- Cleaning. Dirt, weeds and old filler are removed, often by grinding or routing the crack.
- Backer rod. In wider joints, a foam rod is pressed in so the sealant is the right depth.
- Sealant. A flexible sealant, often polyurethane or self-leveling silicone, is applied so it can stretch as slabs move with temperature changes.
Which cracks matter most?
- Joints between the driveway and garage floor
- The gap between a patio, stoop or sidewalk and the foundation
- Cracks where water visibly runs in or weeds grow
- Cracks on slabs that were recently leveled
- Cracks that have widened since last year
Is a crack a sign of a bigger problem?
Hairline shrinkage cracks are normal. Cracks that widen, have one side higher than the other, or keep growing each year usually mean the slab is moving because of settling, heaving or water underneath. Those need leveling or other repair as well as sealing. A contractor can tell you which you're looking at.
When is the best time to seal?
Most sealants need dry concrete and mild temperatures to cure properly, so late spring through early fall is the usual window. Sealing in the fall, before freeze-up, keeps water out of the cracks through winter.
What affects the cost?
- Linear feet of cracks and joints.
- Width and prep. Routing and backer rod add labor.
- Sealant type.
- Combining with leveling. Many companies seal as part of a leveling job.
Prices come from the concrete company after they've seen the slab and figured out why it moved. We don't quote prices ourselves, and a phone estimate is only a starting point.
Where we connect you with help
Common questions
Can I seal concrete cracks myself?
Yes, small cracks can be sealed with a flexible concrete sealant from a hardware store. Clean and dry the crack first. Wide or moving cracks are better handled by a pro.
How long does crack sealant last?
It varies by product and exposure. Check sealed joints each spring and reseal where the sealant has pulled away.
Related services
- Concrete leveling (mudjacking and foam)
- Driveway repair and replacement
- Sidewalk repair
- Steps, stoops and patios
More background: Sioux Falls concrete repair guide.
Sunken slab or a trip hazard by the door?
Call now and a local concrete company will come look and quote the fix.