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.
This one shows the best example of the effect I was trying to explain. I do not have a shot that shows how the handrail goes past the ceiling, but with a little imagination you could picture what the rail would have to do if the stairs were much wider at the bottom.
Best Answer
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.