What is the generally accepted thickness for concrete floors, such as for garages?

The generally accepted thickness for concrete floors, including those in garages, is 4 inches. This thickness is widely recognized as providing adequate strength and durability to support typical loads, such as vehicles and stored items. A 4-inch slab ensures that the concrete can withstand the stress of vehicle traffic without cracking or failing over time.

While thicknesses of 2 1/2, 3, and 3 1/2 inches might be considered in specific applications or under lighter loads, they are not typically advisable for garage floors, which require more resilience. A thinner slab may lead to issues such as cracking, settling, or not providing enough structural integrity to handle the weight of cars and other heavy items commonly found in garages.