Single Garage Slab Concrete Calculator
A single garage slab forms the foundation for your garage structure while providing a durable surface for vehicle storage. Unlike open driveways, garage slabs have specific requirements related to structure support, door clearances, and the protected environment they provide.
Standard Single Garage Dimensions
A typical single garage measures 6x3 metres internally, providing adequate space for a standard vehicle plus some side clearance. When calculating slab size, add thickness allowances for walls if the garage hasn't been built yet. External dimensions might be 6.2x3.2 metres to accommodate standard wall framing.
Slab Thickness Requirements
Garage slabs should be 125mm thick to handle vehicle weight plus any additional loads from storage. The slab also supports the garage walls and roof structure, adding to the total load. Don't be tempted to reduce thickness thinking the enclosed environment protects the concrete, as vehicle loads are the primary concern.
Edge Beams for Structure Support
Most garage designs require edge beams or thickenings where walls will sit. These are typically 300mm wide and 300mm deep, formed beneath the slab perimeter. Your garage plans will specify edge beam requirements based on wall construction and roof loads. Factor this additional concrete into your calculations.
Bolt-Down and Bracket Locations
Plan hold-down bolt positions before pouring. Modern garage frames require numerous bolts at specific spacings, with positions determined by engineering calculations. Have your garage supplier provide exact bolt locations and set them into the wet concrete during the pour.
Internal Floor Level
Set your garage floor level considering the finished ground level outside. The slab should be slightly above external ground to prevent water ingress, typically 25-50mm. Also consider whether you'll add a floor coating later, which adds a few millimetres to the final height.
Building Approval Requirements
Garages typically require building approval in most Australian jurisdictions. This includes slab specifications that must match approved engineering. Don't pour your slab until you have approved plans, as retrospective changes can be costly or impossible.
Need Different Dimensions?
Use our concrete slab calculator to enter your exact measurements and get instant results. You can also compare bags vs ready-mix costs for your specific project volume.