existing 5/4" pine flooring (no sub-floor). half the room is decent but the boards have gaps between that have been caulked, or some kind of gasket. other half of the room has another layer of fir flooring on top that would be ripped out, expose a bunch of nail holes, etc... or go over this stuff again with new t&g pine.
what i'd like to do is rip out all the flooring down to the joists, new 3/4" t&g plywood, new 3/4" t&g pine flooring.
the joists are on 2' centers. would the plywood be rigid enough here? i don't want to get into redoing all the joists, sistering, girders, etc...
i'm pretty sure 24" is the max span per code; i'm just not sure about the deflection.
in the end it would be much easier to rip everything out and start fresh, assuming i can get away with the new subfloor 24" OC.
I don't know, but if you can't get a definitive answer, why not use thicker plywood? Or, run blocking between the joists every 2-4'. I'd GUESS that a 2x4 every 4' as blocking would suffice. Mock one up and try it out. Have someone do jumping jacks above and see/hear what the floor does.