Concrete for Deck Footings (6 Pad Footings)
Decks rely on concrete footings to transfer structural loads to the ground. The number and size of footings depends on deck dimensions, expected loads, and soil conditions. This guide covers standard six-footing arrangements for typical residential decks.
Standard Deck Footing Specifications
Most residential deck plans specify 450x450mm pad footings at 400mm depth. This size supports typical deck loads while providing adequate resistance to lateral forces. Your deck design should include specific footing requirements, as these vary based on deck dimensions and post spacing.
Concrete Volume Calculation
Each 450x450x400mm footing requires approximately 0.081 cubic metres of concrete. Six footings total 0.486m³, or approximately 0.54m³ with wastage allowance. This translates to 58 bags of premix, approaching the threshold where ready-mix becomes practical.
Position Accuracy Critical
Deck footings must align precisely with post positions from your deck plan. Set out positions using builder's string lines and verify dimensions multiple times. Square decks require careful checking of diagonals to confirm right angles before excavation begins.
Height Coordination
While finished deck height comes from post length and framing details, footing positions must account for expected finished levels. Consider bearer and joist depths plus any anticipated ground level changes when establishing footing depths.
Steel Stirrup Requirements
Building codes require timber deck posts to be kept above ground level. Galvanised steel stirrup brackets cast into footings support posts while maintaining clearance. Stirrup sizes must match your post dimensions; verify compatibility before concreting.
Inspection Points
Most deck projects require building approval with staged inspections. Footings typically need inspection before concrete placement (hole depth and position) and again after curing before framing proceeds. Understand your inspection requirements to avoid delays or rejected work.
Need Different Specifications?
Use our footing calculator to enter your exact dimensions. You can also explore our slab calculator if you're considering a full slab instead of footings.