My indoor basement stair treads are currently made of 5/8 OSB nailed to the stringers.

I plan to replace them with new glue+screw plywood.

I'm considering 3/4 Baltic Birch ply for this because of its exceptional stability and exterior-grade glue on all layers.

I'm also considering 1-1/4 plywood but I wonder if the thicker+fewer layers and different adhesives actually make it less performative.

Cost differences are negligible.

Is Baltic Birch appropriate for this use? Should I prefer 1-1/4 plywood?

I'm aware of the code for height of risers and it's not relevant to this decision.


I don’t see an advantage of using hardwood veneer plywood over spf veneer plywood, unless it’s going to be your “finish” layer.

Yes, thicker is better, but required thickness is a product of span, (how far apart the stringers are located).

Those numbers (48/24 for example) stamped on the plywood mean maximum span for roofs followed by maximum span for floors...but that is for subfloor, not finish floor.

  • I'm going to install hard wood over them. I guess im thinking the Baltic Birch will be stronger and keep together better than generic ccx fir ply or osb
    – Matthew
    Sep 9 '18 at 1:07
  • @Matthew I don’t think one type of plywood is stronger than another, but make sure the top and bottom plies run perpendicular to supports.
    – Lee Sam
    Sep 9 '18 at 1:13

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