ZeroGap / Subframe planning
ZeroGap decking calculator
Enter your deck dimensions to estimate the pedestal and aluminum joist subframe for ZeroGap decking.
Deck: 12 ft along joists × 12 ft across joists (144 sq ft) | Maximum spacing: 2.5 ft along joists; 1.3 ft between rows | Joist stock length: 8.9 ft
Pedestals
11 rows × 6 pedestals per row
8.9 ft aluminum joists
11 rows × 2 lengths at 8.9 ft
Your subframe, mapped.
Shared support at joist joints
Repeat for 11 rows. 132 linear ft installed; 195.8 linear ft purchased before extras.
Assumes the two joist ends at each joint can share one pedestal. Supports are included at both edges. Spacing is adjusted to stay within your entered limits and place joints at support positions.
How this estimate is calculated
Joist rows = ceil(12 ÷ 1.3) + 1 = 11.
11 rows × 6 pedestals per row = 66 pedestals.
11 rows × ceil(12 ÷ 8.9) = 22 stock joists.
The planner rounds up to whole rows and whole stock lengths, then chooses cuts so every joint sits at a support position. For some dimensions, supported joints require more pedestal positions than a simple uninterrupted grid.
Joist quantities use whole lengths for each row. Offcuts are not reused between rows. Cuts are nominal; saw kerf and connector gaps are not modeled. Optional extras use ceil(base quantity × (1 + allowance ÷ 100)).
All inputs are decimal feet: 1.3 ft = 15.6 inches; 8.9 ft = 106.8 inches. Spacing values are your planning inputs, not verified span ratings.
Material estimate only. Confirm permitted spans and joint details for your selected system. Excludes perimeter framing, blocking, fixings, decking boards, and special site conditions.