This is a floating deck to be supported by ground screw anchors. There is space for 2 x 6 joists in all but one area where the ground is elevated and not enough clearance for a 2 x 6 so I'm wondering if I could use a 4 x 4 for this one joist. The elevation consists mostly of surface tree roots that cannot be disturbed without possibly killing the tree so I am very reluctant to shave off 2 - 3 inches of roots so the 2 x 6 will fit.

  • 16” centers? What’s the clear span? Jun 18 at 1:11
  • Are you able to post a photo? To be clear, are you talking about shortening the joist? By how much? Jun 18 at 5:50
  • Also, what do you mean by "deck truss?"
    – Huesmann
    Jun 18 at 12:07

1 Answer 1


A 2x6 is almost 70% more rigid than a 4x4 in the vertical axis. A 4x4 might not provide enough rigidity.

If the clearance is that important an issue, use a single metal beam for that location. You'll be able to find a an appropriately rigid box-sectiom beam that is small enough.

Alternatively use several 4x4s to replace the 2x6.

  • Yes, it looks like a double 4x4 is a bit better a single 2x6.
    – Huesmann
    Jun 18 at 12:07

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