One of the most common questions in DIY masonry is: "How thick does my slab need to be?" The difference between 4 inches and 6 inches might seem small, but it increases the strength (and the cost) significantly.
The 4-Inch Standard
A 4-inch slab is the industry standard for residential sidewalks, patios, and garage floors that will hold standard passenger vehicles.
- Best for: Patios, walkways, garden sheds, hot tub pads.
- Reinforcement: Wire mesh or structural fiber is usually sufficient.
The 6-Inch Upgrade
A 6-inch slab provides heavy-duty support. It's approximately 50% stronger than a 4-inch slab.
- Best for: Driveways for heavy trucks, RV pads, workshops with heavy machinery.
- Reinforcement: Requires #3 or #4 rebar grid (18-24" spacing) to be effective.
The 50% Rule
Going from 4 inches to 6 inches increases your material costs by exactly 50%. Before you pour, verify your volume calculation.
Don't Forget Compaction
Regardless of thickness, concrete will crack if the ground underneath settles. Always use a 4-inch base of compacted gravel before pouring.