Garage Slab Thickness

Garages often work well at 4–5 inches with a good base and joints. Consider thicker edges at doors or where heavier vehicles concentrate.

Typical thickness starting points

• Start with the slab thickness calculator for a coherent thickness + PSI + rebar recommendation.
• Increase thickness for heavier vehicles, poor soils, or frequent turning loads.
• Do not reduce thickness to “save concrete” if your base or drainage is weak.

Rebar and crack control

• Rebar helps hold cracks tight and improve load distribution when detailed and placed properly.
• Control joints are still necessary; steel does not eliminate shrinkage cracking.
• Edge thickening and joint layout often matter more than adding steel.

Base and drainage

• Remove organics and soft spots; compact in lifts.
• Keep water away from slab edges; prevent base saturation.
• Uniform base thickness prevents weak transitions.