When building a Floating Foundation Deck System, we recommend a maximum height of 60 inches. The 60" measurement is from the ground to the top of the decking.
For deck heights above 30 inches and below 60 inches, 2"x4" diagonal
bracing is REQUIRED around the perimeter of the deck. Attach
a 2"x4" treated board from the bottom of one 4"x4" post to the top
of the next 4"x4" post. Repeat this on all four sides of the