Construction
Why Concrete Driveways Crack
Concrete shrinks as it cures, so some cracking is a property of the material rather than a defect. The job of the contractor is to control where it happens using joints cut early and spaced correctly. Cracking becomes a real problem when it comes from inadequate base support, insufficient thickness for the loading, water reaching the ground underneath, or joints that were placed too late or too far apart.
Shrinkage cracking
As water leaves curing concrete, the slab shrinks. If it cannot shrink freely, it cracks. Control joints give the shrinkage a planned location, which is why joint spacing and timing are part of the plan rather than an afterthought.
Settlement cracking
When support under a slab is uneven, sections move relative to each other. These cracks are usually wider, often show a vertical step between sides, and indicate a base problem rather than a concrete problem.
Plastic shrinkage cracking
Sun and wind pulling moisture from a fresh surface faster than it can rise from the slab produces short, irregular surface cracks within hours of placement. It is prevented by scheduling, protection, and correct finishing rather than corrected afterward.
Which cracks to worry about
Tight hairline cracks in a slab that is otherwise level are normal. Widening cracks, vertical displacement between panels, and cracks that admit water into the base all warrant an assessment.
- Tight and level: monitor
- Widening over a season: assess
- Vertical step between sides: base problem
- Multiple panels affected: evaluate replacement
Answers
Frequently asked questions
Should I seal cracks in my driveway?
Sealing keeps water out of the base, which is worth doing on stable cracks. It does not correct movement, so a crack that keeps widening needs a look at what is happening underneath.
Is a crack in a new driveway a warranty issue?
It depends on the type and location. Tight shrinkage cracking is normal concrete behavior. Cracking from base failure or workmanship is a different matter, and the coverage categories are published on our workmanship warranty page.
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