About to build a stage, and wondering, what is the purpose of the second layer of wood on top of the stage?

I'm building it out of 2x10s, 16" oc., and 3/4" plywood for the top. I'm planning 2 layers of 3/4" plywood with GG between them, but then I started wondering if this is overkill / does it serve some purpose? Seems the stage will be heavy and strong without the second layer of plywood. On the other hand, it doesn't cost that much, so if it does SOMETHING I'll go ahead with it.

[BTW, hope this post isn't a faux pas, but I'm afraid some questions get lost in my (poorly named) build thread. So I might have to split a couple specific questions out...]

Purpose: To stimulate the economy! :p



OK maybe not. In my limited understanding the purpose is to add mass and reduce vibration. Two layers of OSB laminated together is extremely strong, heavy, and less prone to movement (think flexing, not actually moving around on the joists).

Are you going to have a sub on your stage? If so, it may help limit stage vibration and let the sub work. If not, and if the stage is not part of your isolation barrier, than I'm not sure it matters.

Okay, thanks.

Yes, the stage will have a sub. It will also be sand filled.

I'm going with two layers of 3/4" plywood then, one is regular plywood and the other is birch or beach. I doubt I will let the wood show, planning on carpeting over the stage, but just in case. This think will definitely be a monster in terms of mass when it's finished.

With all the weight, I hope it is in the basement!!
:)

It is! I think the 4" concrete slab will hold it :)