How wide is a typical bored pier hole?

Residential bored piers commonly range from around 300mm to 450mm in diameter, though the genuinely correct diameter for your project is determined by your engineer based on the loads the pier needs to carry and your site’s specific soil conditions — not a generic standard size applied regardless of project.

Larger diameter piers carry greater load capacity but require correspondingly larger drilling equipment and more excavated spoil to manage. Your engineer balances pier diameter against depth and quantity to arrive at the most appropriate, cost-effective design for your specific structure.

This figure is confirmed as part of your engineering design, not something to estimate independently before that design work is complete.

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