Rebar Spacing by Slab Thickness
Practical starting points for rebar size and spacing by slab thickness. This is not engineered design—use it to orient your plan.
| Slab thickness | Load | Starting point | Notes |
|---|---|---|---|
| 4" | Light | Mesh or #3 @ 24" o.c. | Focus on joints and base. |
| 4.5–5" | Medium | #3–#4 @ 18–24" o.c. | Common garages/driveways. |
| 6" | Medium/Heavy | #4 @ 12–18" o.c. | Better for heavier vehicles. |
| 8"+ | Heavy | #4–#5 @ 12–18" o.c. (often engineered) | Industrial/point loads. |
| Spacing and sizing vary by design, base, joints, and local requirements. Use engineered design for heavy/structural work. | |||