Concrete for a 600mm Diameter Post Hole
Large-diameter post holes are specified for heavy-duty applications requiring maximum stability. A 600mm hole is common for substantial structures like shade sails, large pergolas, or commercial signage where lateral loads are significant.
When 600mm Holes are Required
Standard fence posts rarely need holes this large. The 600mm specification typically appears in engineered designs for shade structures, cantilever awnings, high fences exposed to wind loads, or posts supporting significant weight. Always follow engineering specifications if they're provided for your project.
Volume Calculation
A 600mm diameter hole at 600mm depth contains approximately 0.17 cubic metres of space. After accounting for the post and adding wastage, expect to need around 0.16-0.18 cubic metres of concrete per hole, equivalent to 17-20 bags of premix or 1/6 of a cubic metre of ready-mix.
Digging Large Holes
Hand-digging 600mm holes is extremely labour-intensive. A standard fence post auger won't achieve this diameter. Options include manual excavation with shovel and mattock, hiring a larger auger, or engaging a contractor with appropriate equipment. Budget significant time if digging manually.
Concrete Placement Considerations
The volume of concrete in large holes makes quick-set products impractical. Standard concrete allows adequate working time for proper consolidation and post positioning. Plan for temporary bracing while the concrete cures over 24-48 hours before applying any load to the post.
Reinforcement Options
For critical structural applications, consider adding reinforcement to large post holes. A cage of N12 bars around the post, extending into the footing concrete, significantly improves load capacity and resistance to movement. Consult engineering specifications for your specific requirements.
Structural Certification
Projects requiring 600mm post holes often need building certification. Have your plans checked and approved before commencing work. Inspectors may need to verify hole dimensions and reinforcement placement before concrete is placed.
Need Different Specifications?
Use our post hole calculator to enter your exact hole dimensions and post size. You can also explore our slab calculator or footing calculator for other concrete projects.