Acoustical insulation for stack vent

Two (maybe 2.5?) inch ABS vents kitchen sink in 2x4 exterior wall.
Insulate with fiberglass? Or, sprayed foam? Note not much room *around* pipe given dimensions of wall.
My thinking is sprayed foam might conduct more sound than the fiberglass (?)
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Yep. Wrap with dynamat. Any space left, use fiberglass.
Vent makes noise ?
Greg
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On 3/1/2016 2:47 AM, gregz wrote:

Dynamat seems like overkill. I could likewise fill that void with *sand*... :>

Just the "tinkle" of water draining through it. Nothing to lose sleep over but I've got that part of the wall open so now is a great time to make any "adjustments".
Presently nothing in it (the cavity is only a couple of inches wider than the stand pipe). The first inclination was just to use "great stuff" and turn it into a solid block surrounding the pipe.
But, that might just CONDUCT the sounds, better. And, a lot harder to undo! :-/
Could also wrap with a thin layer of fiberglass then rubberized membrane, then more fiberglass (changing the density at each layer to absorb different frequencies)
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Don't use great stuff. You could try some soft foam. Either soft gummy hvac foam, not the polypropolyne type, or less effective open cell foam stuffing. You could also wrap it with rubber mat flooring sold by the foot.
Greg
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On Wednesday, March 2, 2016 at 3:49:42 AM UTC-5, Gz wrote:

they also sell PVC drain line with anti noise coating
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On 3/2/2016 6:01 AM, bob haller wrote:

I'll keep that in mind -- *if* I break something an need to replumb the stack. NOT something I want to do! Trying to get all this stuff done BEFORE it gets much hotter (current mid 80's are only "uncomfortable"; 90's will start to be annoying!)
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On 3/2/2016 1:46 AM, gregz wrote:

If the rubber matting would work, I could wrap it in FortiFlash (about 1/8" thick -- multiple layers?). Keep in mind, there's not much space around the pipe owing to the thickness (THINness?) of the wall. And, I'm reasonably sure I don't want it to rub against the interior as it would inevitably make noises as the house "moves".
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use hubless cast iron pipe it connects with ferncos and definetely insulate and insulate and sound proff with foam. it prevents sound transmission by preventing air leakage from the area
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On 3/1/2016 3:10 PM, bob haller wrote:

I can't replace the stack (well, I *could* replace just the vent portion). And, am really hesitant to tinker with the drain "T" as it's into the slab from there. I.e., break anything and you're quickly facing the problem of the carpenter trimming chair legs: "Hmmm... STILL too short!"

So, anything that breaks the path of the "pressure wave"?
I'm reluctant to cast the entire thing in (solid) foam as any work that would need to be done -- once I get the tongue-groove planks in place -- would require a HUGE amount of effort (i.e., remove ~10-12 planks *OR* remove countertop and three cabinets) just to access that portion of the wall, vent, drain, clean-out, etc.
[Hence the reason for undertaking these sorts of things BEFORE I close up the wall!]
How would "solid" foam compare to, e.g., densely packed fiberglass? Or, LOOSELY packed fiberglass (I'd imagine dense would be better)?
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What about spraying it with automobile undercoating stuff? I have seen it used for soundproofing on cars in trunks and firewalls where replacement activities had eliminated the original rubbery stuff.
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On 3/2/2016 8:39 AM, snipped-for-privacy@att.net wrote:

Google turned up lots of hits (esp YouTube) for this sort of thing. But, mostly "kids" trying to insulate the sound systems in their ghetto cruisers.
Different sounds (frequency ranges) require different sorts of treatment (above my pay grade). I recall having to help a friend design a "muffler" for the ventilation system on a piece of military test equipment. It was very frustrating trying to figure out what you needed to change to achieve a desired result (in his case, without impeding air flow!)
My main concern is not wanting to make *more* work at some future date. Esp if (as I get older and less willing/capable of taking on these chores) someone ELSE is called upon to address future issues! We've made lots of little customizations, here (and some BIG ones!) that would surprise (and, in some cases, CONFOUND!) many tradesmen.
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Pretty thin.
Greg
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On 02/29/2016 05:36 PM, Don Y wrote:

Is ROXUL SAFE‘n’SOUND^® better than fiberglass or is it just marketing hype?
http://www.roxul.com/products/residential/products/roxul+safe 'n'sound
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In typed:

Roxul may be an option. But, I don't know where the OP could buy just the small amount of it that he would need for this one application.
I also don't know offhand where someone could buy small amounts of foam rubber or something similar. But, something like that may be the easiest, cheapest, and quickest easily-removed sound proofing solution for this situation.
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I think it's more dense from what I remember. You could compress fiberglass and not worry about heat transfer.
Greg
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