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More mass or decouple a shared wall

Posted: Fri May 11, 2007 4:32 pm
by gdizzle
In my small live room, (10x12), one wall shares an exterior wall. The other 3 walls do not. The wall in question , from outside - in, is Painted Redwood siding, R 13 insulation, 1/2in sheetrock, paint. (2x4)and I mean OLD 2x4 where that is the actual size of the lumber.
I was thinking I could just bulk it up from the inside by adding 5/8 sheetrock with adhesive.
Then I wondered (I did buy Rod book) is using the resilient channel in between would do any better as far as keep sound in. Can I put the channel ontop of the drywall?? Or does it defeat the purpose?
Or should I tear out the 1/2 and install res. channel then 5/8?
I am hoping just sandwiching them will do.
Ideas, or comments please??

Re: More mass or decouple a shared wall

Posted: Fri May 11, 2007 10:43 pm
by rod gervais
gdizzle wrote:In my small live room, (10x12), one wall shares an exterior wall. The other 3 walls do not. The wall in question , from outside - in, is Painted Redwood siding, R 13 insulation, 1/2in sheetrock, paint. (2x4)and I mean OLD 2x4 where that is the actual size of the lumber.
I was thinking I could just bulk it up from the inside by adding 5/8 sheetrock with adhesive.
Then I wondered (I did buy Rod book) is using the resilient channel in between would do any better as far as keep sound in. Can I put the channel ontop of the drywall?? Or does it defeat the purpose?
Or should I tear out the 1/2 and install res. channel then 5/8?
I am hoping just sandwiching them will do.
Ideas, or comments please??

How about some homework - go back to chapter 4 - and re-read the first paragraph on page 56 - and then the next to last on the same page.


Rod

Posted: Sat May 12, 2007 3:01 am
by gdizzle
Wow this is big. Thanks Rod for reply. Maybe you'll sign my book?? I read it last night, and also today. I think what it means is putting extra layers doesnt do much, but adding more "mass" inside the wall does help. So I had mentioned I have R13 (I think, its whatever would fit) in the wall. Are you saying remove that?? And put something else in, and then put the drywall back on?
I actually just came across some idea from another thread that suggests cutting up drywall pieces and putting it inside the wall?? Can this really do anything? Doesn't that create surface to surface contact? Low freq transmission would simply travel from inside to out?

Is what needs to be done is remove as much "air" space as possible inside the wall??
Keeping in mind this is a single wall system, not double. There is nothing I can do to the exterior of this wall, other than silicone between the Redwood siding.
The interior wall I am open to removing the drywall, and packing the cavity with anything. Ever thought about that insulation that is applied as foam? Or do I want it to be as dense as possible??

Sorry for all the question marks.
Thanks for any help.

Posted: Sat May 12, 2007 5:38 am
by sharward
Please keep studying the book, and study the sticky threads here.

Mass-air-mass.

Mass is important, Air is important, Mass is important.

The more, the better.

Keep studying, my friend... :)

--Keith :mrgreen:

Posted: Sat May 12, 2007 5:42 am
by rod gervais
Sorry,


more home work - go back and RE-re-read what I told you =- you got so excited about what you figured out when you read it that you missed the other 1/2

Rod

Posted: Wed May 16, 2007 5:34 am
by gdizzle
I re-read. I am a professor, so it is a great change of pace to get homework instead of give it.
Since your mantra is Mass - Air - Mass, when you point me to your 2nd to bottom paragraph on p. 56, it mentions to remove the inner wall facing, and increase Mass. So to me, this would mean, remove the Inner (in room) 1/2 drywall, remove insulation, add more mass to the exterior wall from the inside. So like I could put 5/8 dry wall right on the back of the redwood siding, maybe use the Green Glue to adhere it, then I could put insulation back in, then put 5/8 drywall over the top. So in theory, I am adding 5/8 mass to exterior wall side, taking away 5/8 air space, adding 1/8 mass to interior face. Is this going to help the STC? The depth , recall, is 4 inches inside. So I could do even more mass still, but each increase in that mass, internally, will decrease Air space. Am I on track?

Posted: Wed May 16, 2007 8:54 pm
by rod gervais
gdizzle wrote:I re-read. I am a professor, so it is a great change of pace to get homework instead of give it.
Since your mantra is Mass - Air - Mass, when you point me to your 2nd to bottom paragraph on p. 56, it mentions to remove the inner wall facing, and increase Mass. So to me, this would mean, remove the Inner (in room) 1/2 drywall, remove insulation, add more mass to the exterior wall from the inside. So like I could put 5/8 dry wall right on the back of the redwood siding, maybe use the Green Glue to adhere it, then I could put insulation back in, then put 5/8 drywall over the top. So in theory, I am adding 5/8 mass to exterior wall side, taking away 5/8 air space, adding 1/8 mass to interior face. Is this going to help the STC? The depth , recall, is 4 inches inside. So I could do even more mass still, but each increase in that mass, internally, will decrease Air space. Am I on track?
gd,

yes you are.

If you remove the drywal by cutting alongside of the framing with a sawzall....... each piece will fit exactly into that bay - so the first layer in the wall is free.

Make sure to caulk the edges properly - use the details I show you with floor joist - it's exactly the same except vertical...........

Once you're done that - you really do need to decouple (for low frequencies more than anything else) the inner face from the outer face - so either RC-1 or he RSIC clips............ and then a layer of drywall - caulk the edges - and another layer of drywall......

exactly how quiet you need to be would make the determination of green glue or not inside he room -

Rod

Posted: Thu May 17, 2007 1:42 am
by sharward
gdizzle wrote:. . . maybe use the Green Glue to adhere it . . .
Use Green Glue: Yes, perhaps, if you need it and can afford it, as its viscoelastic properties are nothing short of amazing.

To adhere: No chance. Green Glue is not an adhesive at all and cannot be used as such. I wish the manufacturer had named it "Green Goo" instead so as to eliminate that common misconception.

--Keith :mrgreen: