wall vs. ceiling question

I am going to be putting 5/8" drywall on my walls with r-13 insulation in the stud cavity. My basement ceiling is normal 3/4" plywood subfloor with I-beams 16" oc (bottom of floor joist 8.5'). My ceiling will have r-13 in the cavity, but putting drywall directly at the bottom of the subfloor is not possible as there is alot of HVAC present (basement was like this when I bought it). My question is: will adding 2 layers of 5/8" drywall at the bottom of the floor joists provide the same amount of isolation as that of my walls (5/8"--r-13, -- 5/8")? I am trying to prevent the noise of my soon-to-be studio from seeping into the main floor where we live. Thanks Justin

Justin - this is the predominant problem with the US basement studio. There are HVAC ducts, plumbing pipes, electricity cables etc. running throughout the ceilings of basements. First check out what can be moved, for example electric cables can be tucked up into the gap between the joists and tied down. I have a US basement studio going up now where we actually moved the whole HVAC to make room for the studio and new ducts were run between the joists to free up the ceiling joists. We also moved a jack post and added another I-Beam running parallel to it to make up for the loss of the post. It can be done. there are basically two ways you can support you new ceiling and I've attached a drawing showing the two methods. Version 1 uses RC and the better the RC method (i.e proper RC as opposed to hat channel) the better isolation. (see pic in drawing.) Version 2 is probably the best method but it's not always possible because of all those damn pipes and ducts. In both systems the addition of Green Glue will improve the overall STC. see I'm not anti GG :D I hope this helps - I've also attached a .pdf version of the drawing. cheers john