The slab design should reflect intended use and the conditions beneath the concrete. A thicker slab cannot automatically compensate for poor base preparation or drainage.
Start with intended use
Pedestrian furniture loads are different from hot tubs, heavy outdoor kitchens or equipment.
Base and soil matter
Excavation, drainage, compaction and granular base influence how the slab is supported.
Climate and local practice matter
Freeze-thaw exposure, expansive soils and local requirements may change the recommended assembly.
Calculate volume after design
Once thickness is selected appropriately, use the Concrete Calculator to convert patio length, width and thickness into cubic yards.
Run your own numbers: After the design is decided, calculate volume with the Concrete Calculator.