Collect the allowable spans
The deck board determines the maximum joist centres. The joist section, species or profile determines the maximum pedestal spacing. The pedestal then sets its own base and load conditions.
Treat every figure as a manufacturer specification and use the most restrictive value that applies to your layout.
Set out the joist lines
- 1Joists
- 2Pedestals
- 3Centre-to-centre grid
Run them perpendicular to the boards. Add edge supports, strengthening members, double joists at board-end joints and supports beneath cut-outs before calculating quantities.
Set out the pedestals along each line
- 1Joists
- 2Pedestals
- 3Centre-to-centre grid
Position the end supports first, then distribute intermediate supports without exceeding the allowable span. A division-based count must include both ends.
Calculate the support grid and pedestal countTesCalculs→Level and secure the structure
Level the ends first, pull a string line between them and adjust the intermediate supports. Secure the joists as specified and protect their top face where the instructions require it.
Check before laying the boards
Check squareness, level, the stability of every pedestal, continuous support, ventilation and drainage. Correct faults now; they will be harder to reach once the surface is installed.