Size the concrete, the gravel base and the form boards for a patio, shed floor or pad.
How it works
Slab volume with 10% added, in yards or bags. The base layer adds 15% for compaction, and forms equal the perimeter.
Before you order
- Four inches suits most patios and walks, while vehicle slabs are usually thicker. Your plans and local code decide.
- Compact the base in lifts and check it with a level string before forming.
- Cut control joints within about a day so cracks follow the lines you chose.
Common questions
How thick should a concrete slab be?
Four inches is common for patios and walks. Driveways and garage floors are often five to six inches, depending on local code and loads.
Do I need gravel under a slab?
A compacted gravel base is common because it gives even support and helps with drainage. Your local code or plans may require it.