Concrete for a 6x6 Metre Shed or Garage Slab
A 6x6 metre slab encompasses 36 square metres, making it suitable for double garages, substantial workshops, or large storage buildings. Projects of this scale typically warrant professional involvement or significant DIY experience, though the calculation principles remain straightforward.
Volume and Cost Overview
At 100mm depth, a 6x6 metre slab requires 3.6 cubic metres of concrete. With 10% wastage factored in, budget for approximately 3.96 cubic metres or roughly 428 bags of premix. Ready-mix is the only sensible option at this volume, with concrete costs ranging from $1,100 to $1,650 plus delivery and potential pump hire.
Access and Pump Requirements
Concrete trucks typically extend chutes 2-3 metres from the vehicle. For a 6x6 slab, you'll likely need the truck to reposition during the pour or require a concrete pump. Line pumps typically cost $300-500 for a job this size but dramatically simplify placement and reduce labour requirements.
Control Joint Planning
Slabs exceeding 30 square metres should include control joints to manage cracking. Plan joint locations to create panels no larger than 4.5 metres in any direction. For a 6x6 slab, a single cross joint creating four 3x3 metre panels is typical. Cut or tool joints to one-quarter slab depth.
Reinforcement Strategy
Large slabs benefit from careful reinforcement planning. Beyond standard mesh, consider additional bar reinforcement around edges and re-entrant corners. If the slab will support columns or posts, detail additional reinforcement at these locations. Your steel supplier can advise on cutting and bending requirements.
Council and Certification Requirements
Slabs of this size often require building approval, particularly if supporting structures like garages or carports. Many councils require engineer-designed footings for buildings exceeding certain sizes. Contact your local council's planning department before commencing work to understand your obligations.
When to Hire Professionals
A 6x6 pour is ambitious for inexperienced DIYers. Consider the consequences of getting it wrong against the cost of professional assistance. Many concreters offer labour-only arrangements where you supply the concrete and they handle placement and finishing, providing a cost-effective middle ground.
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.