Why Concrete Cracks Where It Does

Concrete shrinks as it cures. It will crack. The only real question is whether it cracks where somebody decided it should.

Control Joints Are Planned Cracks

A control joint is a weakened line that gives the slab somewhere to relieve stress. Cut too shallow or too late, and the slab picks its own line instead.

Spacing Follows Thickness

A common rule puts joint spacing in feet at two to three times the slab thickness in inches. Wide open bays without joints are a decision, and usually not a good one.

• Cut depth at least one quarter of slab thickness
• Cut within the first day, sooner in heat
• Keep panels close to square
• Isolate columns, walls and anything rigid

Subgrade Does the Quiet Work

Uniform, compacted, well drained base prevents the differential settlement that produces the cracks nobody can explain later.

Ask a contractor where the joints go before you ask what the pour costs. The first answer predicts the second.