This is the "[[url=http://[/URL]="http://recording.or…"]Studio Construction & Acoustics Forum[/]="http://recording.or…"]Studio Construction & Acoustics Forum[/]" not the "Let me throw some stuff out there and see if it sticks Forum".

The OP said

Can I put 3 layers up safely?

My answer is yes - if the sheet material stands on the floor.

I've given you the chance to offer a contrary view - why do you always fall back on the insults? I've explained it, and I tried very hard to make sure the OPs question was answered. A lightweight stud will fail from over-compression, but that doesn't come from the sheet material, as I have explained.

Your answer is wrong.

You do not know his situation or how this metal stud partition is erected. All you know is that you do not consider gravity or Newtons Law "for ever action there is an equal and opposite re-action", or local code or experience or health to be admissible items to consider. Nor do you take into account the money that is well wasted by simply saying "Yes...do as i say because i have an ex-college lecturer hat on so this makes me relevant".

The fact that 3 layers is a waste of money on materials and labor does not seem to bother you in the least. I spend other peoples money every day of the week and if I were not good at taking care of said monies, I would not have a job.

3 layers is a waste since you will not get the benefit that you would if you used 4 layers. But the fact still remains that there is no way, based on data and experience that 3 layers should be applied to this assembly since there are too many unknown factors.

What are the isolation requirements? Simply installing 3 layers does not take into account what the rest of the environment is. Does it even make sense to install 2 layers when the rest of the room has only one layer or is a fully coupled environment with nothing gained from adding more mass since flanking and/or windows/doors will be the weak link.

These are things that no one in this thread knows at this point, especially you my ex-college lecturer hat on friend.

Can it be done safely? I say no...and what I say goes...your opinion is just that, an uneducated opinion from someone who has not found his place on this board.

Your ability to be verbose or talk too much should not be taken by anyone, especially yourself, as meaning you have the answers. You clearly do not. What you do is attempt to "think" your way through things. Well and fine if this were liberal arts but it is not.

It is tried and true data and technique and acceptable building practice...not conjecture.

You cannot, in this forum, talk about construction without talking about acoustics, until you develop that insight you will continue to be squashed or rather your "opine" will be sent to the trash can. At some point you may get it, I suspect it will be a long uphill climb for both of us since you have shown no modification to this respect since you have been here and I firmly believe that YOU believe that "just because I can think...I am vital."

And this is dangerous to people who are asking for help who may or may not know what they are doing or what they are about to get into.

Now, I will say this in your defense. Clearly the sheetrock should sit firmly on the foundation and yes the fasteners, what you call
fixins", are to be considered. But there is a pattern that should be adhered to when installing sheetrock in multiple layers. You have yet to bring that to the posters attention, another one of your short comings.

According to usg.com the fixin pattern should be 8 inchs/25 millimeters apart on the interior of the sheathing, what we call "the field". The perimeter should be nailed within 3/8 of an inch from the panel edge.

Flexibility versus rigidity, there is the rub. To reduce the rigidity the fastener pattern has to be taken into consideration. So how many layers you install dictate the pattern
with the final layer being applied with the full schedule of fasteners.

I am going to consider this matter closed, since I am a nice guy no matter what your opinion is in respect to that. Should you choose to belabor this any further I will consider it only in as much as your posts are either relevant or topical.

Anything outside of that...and I will either remove the post or lock this thread. Like I said, I am a nice man, but my patience is wearing thin.