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Discussion Starter · #1 ·

I have some questions that maybe those more experienced on the forum can help me with.  I'm looking to frame my theater with staggered stud walls, modifying the existing 2x4 stud wall.  Sorry in advance if these questions have been answered, but everything I've come across on the forum describes staggering the studs by 1" by adding a ripped 1" toe plate onto the existing toe plate and then basically toe nailing the new/staggered studs into both the toe plate and top plate.

 

1) Although the studs are decoupled from the adjoining studs and wall, wouldn't this somewhat defeat the purpose of a staggered stud wall by allowing some coupling with the joists above and/or floor below, thereby allowing some flanking to occur?  Is the STC rating for a staggered stud wall taking this flanking into account?

 

2) Could/should this be improved upon by adding brackets (e.g. RSIC-DC04 brackets) between the top of each new stud and the top plate?

 



 

3) Given that I'm also planning on floating a ceiling from a ledger board attached to the staggered studs, is the placement of isolation brackets atop each stud sufficient, not enough, or overkill to stabilize and support any load?

 



 

Any help would be greatly appreciated.
 

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Decoupling the top of wall framing is a good idea. You can simply decouple the top plate by building the wall 1 inch short and using IB3 clips. I seem to recall the method proposed of putting a clip on each stud but that seems pretty tedious.
 

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Discussion Starter · #5 ·

Quote:
Originally Posted by BIGmouthinDC  /t/1519871/staggered-stud-help#post_24410563


Decoupling the top of wall framing is a good idea. You can simply decouple the top plate by building the wall 1 inch short and using IB3 clips. I seem to recall the method proposed of putting a clip on each stud but that seems pretty tedious.
 

That is what I was thinking, one clip per stud.  I was thinking I could do every other stud, especially since the wall and studs would be bound and stiffened a bit by a ledgerboard and possibly OSB on the 1st surface.  But given that I'm also going to float the ceiling from the studs I thought I'd do every stud to be on the safe side for stability.  I think I've got about 40 clips then I'm going to have to stick on the top of the studs... going to be fun.

 
Quote:
Originally Posted by Mfusick  /t/1519871/staggered-stud-help#post_24410529


Can you do a double wall?
 

I could but then my room would be rather narrow, so I've ruled that out as an option.  I figured staggering the studs would be the next best way of isolating the room.
 

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Discussion Starter · #6 ·

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Originally Posted by tsandtsand  /t/1519871/staggered-stud-help#post_24410036


This old HUD document has some great soundproofing examples, specifically for staggard walls, about 3/4 down the page.

http://portalapps.hud.gov/hudstracat/noise/viewMaterial.jsp?cat=WALL&return=wall_3


 
 

Who knew there were this many variations on soundproofing a wall!  This is like the starbucks menu of wall isolation... I'd like a grande staggered stud wall, with metal studs, 2 layers of 5/8 double drywall with green glue, and a dollop of R19 insulation please.
 

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Discussion Starter · #9 ·

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Originally Posted by Swervepf  /t/1519871/staggered-stud-help#post_24422555



Soundproofingcompany.com has it the other way around on this page http://www.soundproofingcompany.com/soundproofing101/4-elements-of-soundproofing-for-construction/


 
 

I know there is some variability on wall STC depending on frequency.  e.g. I think a staggered stud wall may be better at isolating lower frequencies, while a clips/channel wall could be slightly better at the higher frequencies?

 

But in general my initial understanding was staggered studs were slightly better as you've cited from Soundproofingcompany.com.  Also, I think most people doing staggered studs have them coupled at the bottom and top plates.  Mine will be decoupled at the top plate.  This has to improve on the staggered stud soundproofing STC.  As for wall thickness comparison, from the level of the original studs, I calculate 2.25" for staggered studs/DD/GG and 2" with clips/channel/DD/GG.  I can live with the extra 1/4", especially if a bit less expensive and I can eek out a bit better STC rating.
 

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Quote:
Originally Posted by Swervepf  /t/1519871/staggered-stud-help#post_24422555


Soundproofingcompany.com has it the other way around on this page http://www.soundproofingcompany.com/soundproofing101/4-elements-of-soundproofing-for-construction/

I stand corrected but what I do not understand with the staggered studs the top 2x6" plate and the bottom 2x6" sill are still coupled. So how is it that the Clips and Channel which totally decouples the DW from the studs is not as effective. Ted and John steered me toward the clips and channel. If the staggered studs are better and cheaper I would have done my side walls that way. I did double stud wall in the rear because that is the best and I had the length of my room to support it.
 

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Discussion Starter · #11 ·

Quote:
Originally Posted by cw5billwade  /t/1519871/staggered-stud-help#post_24428809



I stand corrected but what I do not understand with the staggered studs the top 2x6" plate and the bottom 2x6" sill are still coupled. So how is it that the Clips and Channel which totally decouples the DW from the studs is not as effective. Ted and John steered me toward the clips and channel. If the staggered studs are better and cheaper I would have done my side walls that way. I did double stud wall in the rear because that is the best and I had the length of my room to support it.
 

I'm no sound expert, but from what I've read on the forum and other sites thus far, a lot of the difference in the two types of walls is somewhat dependent on the frequency you are isolating.  So with staggered studs you are creating a larger continuous air cavity which changes the resonance of the wall, this helps with dampening the lower frequencies (the larger the cavity the lower the frequencies are that are dampened).  The decoupling of clips/channel, albeit with a slightly shallower air cavity helps more with higher frequencies.  I'm sure there are also other flanking issues that differ with both walls.  I'm trying for the best of both worlds by increasing the wall air cavity with staggering the studs (which also decouples the studs from the adjoining wall) AND by decoupling those studs from the top plate with DC04 clips.  So in effect, the only coupled part is where the staggered studs are toenailed into the bottom plate.  Theoretically I could also decouple this with additional DC04 clips, but that is getting a little extreme if you ask me and I doubt I'd get much noticeable improvement.

 

I would guess that most of the acoustic comparisons between staggered stud walls and clips/channel involve staggered studs that are coupled at both the top and bottom plates, but again I'm no expert on this so can't say for sure.

 

The best as you've pointed out would be a true double wall, but I and a lot of people just don't have the room for this.  I'm also not expecting to get 100% soundproofing (close to impossible) and I'm happy settling for even 70-80%.  I know that the walls will not be my weak link as I have several doors on my room that will be "leaky".
 

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You are correct that the IB-1 clip and hat channel when combined with a 2x4 wall = 4 5/8" where a staggered stud wall using 2x6 sill and plate construction is 5 1/2" and bigger is better when controlling certain frequencies. Here is what I found from the web page sited above.

The STC of DW/GG/DW on both sides of 2x4 with bat insulation wall = 55


with staggered studs = 56



Also from sound proofing web site STC of Clips and hat channel =66 so I am not sure anymore.
 

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Discussion Starter · #13 ·

Quote:
Originally Posted by cw5billwade  /t/1519871/staggered-stud-help#post_24432499


You are correct that the IB-1 clip and hat channel when combined with a 2x4 wall = 4 5/8" where a staggered stud wall using 2x6 sill and plate construction is 5 1/2" and bigger is better when controlling certain frequencies. Here is what I found from the web page sited above.

The STC of DW/GG/DW on both sides of 2x4 with bat insulation wall = 55


with staggered studs = 56



Also from sound proofing web site STC of Clips and hat channel =66 so I am not sure anymore.

 
 

I'm a bit confused now too. 
    I'd really love to see some data showing the staggered stud wall with top plate decoupling, but not sure it exists.  Ted where are you when we need you?
 

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Decoupling the top plate is a strategy for minimizing the transfer of vibrations to the ceiling structure and floor above. This is important for those of us building in basements. From what I know about STC values they are measured from one side of the wall to the other. Bottom line I don't think having an STC value of a decoupled wall frame is going to be helpful in your decision making.
 

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Discussion Starter · #17 ·

Makes sense.  I could envision the top plate decoupled wall differing only slightly from the standard staggered wall by only a few STC if even that, possibly due to some minimal flanking into the opposite studs.  However, this would probably not be of any significance for the adjoining wall like you've said Big.  As you've said, the real reason is to decouple from the joists and floor above.  So I guess either wall (a top plate decoupled staggered stud wall or clips/channel) will give you that decoupling.  And since STC values of both walls seem to be pretty close... looks like it might be a wash.
 
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