Concrete for 20 Fence Posts: A Complete Guide
Twenty fence posts represents a substantial boundary fence project, potentially spanning 40-50 metres depending on post spacing. Projects of this scale benefit from careful planning, efficient material handling, and realistic scheduling.
Material Requirements
Budget for 50-60 bags of 20kg post mix concrete, representing approximately 1-1.2 tonnes of material. This quantity requires either multiple vehicle trips, trailer transport, or store delivery. Most hardware stores offer free or low-cost delivery for purchases over certain thresholds.
Project Timeline
Digging 20 holes by hand takes most people an entire day, assuming reasonable soil conditions. Rocky or clay soils can double this estimate. Setting all posts typically requires another full day of concentrated effort. Spread the work across two weekends to avoid exhaustion and maintain quality.
Power Auger Consideration
For 20+ holes, hiring a power auger dramatically reduces digging time and physical strain. One-person electric augers suit most fence posts, while petrol-powered two-person augers handle larger holes or difficult soils. Rental costs are typically $80-150 per day, often recovered through time savings.
Post Positioning System
Establish accurate positions using surveyor's string lines and measuring tape. Mark each hole centre with spray paint or a stake. Double-check critical dimensions before digging, as repositioning concrete-set posts is extremely difficult. Verify property boundaries if building boundary fences.
Batch Setting Approach
Work in batches of 4-5 posts rather than trying to set all 20 continuously. This allows quality checks between batches and provides natural rest periods. If a post needs adjustment after initial set, catching it within the batch is easier than discovering problems later.
Weather Contingency
A project spanning multiple days needs weather monitoring. Don't dig holes days before setting if rain is forecast, as waterlogged holes require pumping or bailing before concrete work. Have tarps available to protect open holes if weather turns unexpectedly.
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.