Slab thickness
The depth of a slab, which together with base support and jointing determines how much load it carries and how well it resists cracking.
What does slab thickness mean?
Residential driveways and patios are commonly four inches, with five or six inches used where trucks, RVs, or heavy equipment will park. Adding thickness is usually a better investment than adding strength for load-carrying capacity, but neither compensates for a poorly prepared base. Thickness also sets the required depth of control joint cuts.
In practice
When a homeowner asks whether to upgrade the psi or add an inch of thickness for an RV pad, the inch generally wins.