Physics Test

Posted: Thu Aug 21, 2008 4:41 pm

I've been contemplating the finish process for my walls and studios and this thought got stuck in my head... just so you know where this is coming from.

OK, FORGET practical practice when you contemplate this...

What makes a "better" wall...

A full sheet of gypsum screwed to the studs, or smaller pieces of gypsum? By smaller pieces, I am referring to stud width.

Regardless of stud size or stud spacing, would you have more LF attenuation by cutting to stud width, or putting up full sheets?

What about stiffer mass?

I know it's a pretty goofy set of questions, but what got me thinking is the fact that for part of my ceiling, I will need to cut smaller pieces to ceiling joist width.

Max

Posted: Fri Aug 22, 2008 5:21 am

Use the full sheets with multiple sheets sandwiched together. Mass, you want Mass. You don't want one stinking layer. Plus, little pieces means more air transference. Air is what moves sound. The more airtight, the less transference of sound. So gaping seams covered over in tape & spackling compound won't be as effective as a full solid piece. I won't even broach HVAC. That's a whole 'nother thing. And while wood studs are the best to use, not all jurisdictions allow for that. Some require metal. Nasty, ringy metal studs. Such as Baltimore County.

I like Recording in unfinished garages & warehouses.
Ms. Remy Ann David

Posted: Fri Aug 22, 2008 5:58 am

Max,

the larger the sheet - the more studs/joist it spans - the stiffer the wall.

It might seem to you that smaller pieces are stiffer - but they are not.

Picture that you have to span a full bay anyway - once you do - with a small piece just bay width) the piece can bend in with no interaction on the adjacent framing,

Now picture a full sheet - it spans multiple bays - and if you press into the center of one bay - in order for it to sag into the bay it will have to bow oout in the adjacent 2 bays - which will make it want to sag in slightly in the 2 bays outside of those, etc.

It is exactly the same as with a plywood deck - the strongest deck spans multiple bays - not individual bays.

So this is what you want - to use as large a piece as you can - the small stuff that you might be able to eat up on your ceiling are better suited to the scrap pile - unless they finish off adjacent to a full piece because of the wedge shape of your ceiling.

But a lot of little pieces are NFG......

Rod

Posted: Fri Aug 22, 2008 8:13 pm

Understood, Rod,

I was in the bathroom looking over the day's work and thumped the full pieces of hardi and the sort pieces of hardi...

Obviously, the larger pieces resonated at a lower frequency than the smaller pieces. Couple that with the ceiling's complexity and it just piqued my curiosity as to whether a larger piece of gypsum would provide greater LF attenuation, or whether a smaller piece would.... thus the additional question regarding which would provide a "stiffer" mass.

I'm quite aware of the benefits of mass, Remy... didn't mean to throw ya' a curve on that. It was just one of those things that gets in your head when its late and you're tired. (That's why I'm doing room within a room made of 2x6 stud walls with 3/4" of MDF and two layers of gypsum on each wall.) So, yes... mass is your best friend.

Posted: Fri Aug 22, 2008 11:45 pm

I was in the bathroom looking over my days work. But I flushed and it was all ruined! I'll have to work on that to get back to where it was. It shouldn't be hard after a couple more trips to the Chinese Trough (buffet).

Dealing with a movable mass
Ms. Remy Ann David

Posted: Sat Aug 23, 2008 6:18 am

hehehehehe....

You go girl!

Posted: Sat Aug 23, 2008 6:43 am

She just did.

Posted: Sat Aug 23, 2008 2:50 pm

Seriously...

This shit is pretty fucked up right here...

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