Stuck with a 3 leaf wall. Need advice.
sloper
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#1
23rd June 2013
Old 23rd June 2013
  #1
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Thread Starter
Stuck with a 3 leaf wall. Need advice.

Hopefully someone out there has dealt with this. I'm moving into a new industrial bay that is 20ft wide and 40ft long, and 19ft high. I have neighbours on both sides of me. The current party walls are 5/8 drywall with metal studs and insulation between. I need to isolate myself the best I can especially in low frequencies. I record everything from metal to folk music all at loud volumes and sometimes with very loud drummers. I can't tamper with the existing wall because it is a firewall, so I'll either have to build onto it or in front of it. Removing the drywall on my side is out of the question.

I'm thinking of doing a room within a room even though it would result in a 3 leaf system. I'm wondering if this is a good idea and what some other options might be? I feel that just beefing up my current layer of drywall with green glue will not offer nearly enough isolation.

My floor is concrete so I'm not concerned there, and my roof is metal with insulation compressed onto it, so I may need a false ceiling. I plan on being here for the long haul so I don't mind spending the time and money to do it right.

Thanks in advance!

-Terry
#2
23rd June 2013
Old 23rd June 2013
  #2
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gullfo's Avatar
 

considering hiring someone to design it for you. you'll need to provide a lot more detail on the space and existing construction as well.
#3
23rd June 2013
Old 23rd June 2013
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jhbrandt's Avatar
 

+1

Been there, done that.

You may need to open YOUR side of the partition wall, remove the gypsum board on YOUR side, remove the fiberglass insulation, cut the removed gypboard up into pieces that will fit between the framework or studs. Layer the gypsum board on the BACK side of your neighbor's wall. Fasten it to the stud/framework of the wall (depends on what you have as to how you do it), seal it up with a non-hardening caulk (Big Stretch), replace the fiberglass... THEN build your decoupled walls, etc., etc., etc.

Cheers,
John
#4
23rd June 2013
Old 23rd June 2013
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Rod Gervais's Avatar
 

The fact that the wall is a fire wall doesn't mean it cannot be modified - it simply means that in order to modify it you must maintain (at the minimum) the required fire rating.

This is not a difficult task - as any wall assembly that has a good sound rating will (by extension) have a good fire rating....

Now - if what you are saying is that your lease will not allow you to modify that wall in any manner - that is another thing all together.......

So (at least for me) everything begins there........

Rod
sloper
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#5
23rd June 2013
Old 23rd June 2013
  #5
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Thread Starter
Rob, bought your book years ago. It's an awesome resource.

I'll be purchasing the bay so no lease or landlord to worry about. John, reusing the old drywall is a great idea, I'll definitely be doing that if possible. It's a lot of work, but it is the best way.

So is there any way to do this while leaving the current firewall in tact? Is beefing up the middle layer an option, (now I just sound lazy) or would the three leaf wall be too much of a compromise? Also would I need to attach a ceiling to my new wall structure to isolate the roof?

Thanks guys!

-Terry
#6
23rd June 2013
Old 23rd June 2013
  #6
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Rod Gervais's Avatar
 

Quote:
Originally Posted by sloper View Post
Rob, bought your book years ago. It's an awesome resource.
Thanks for the kind words..... (by the way - it's Rod not Rob )
Quote:
I'll be purchasing the bay so no lease or landlord to worry about. John, reusing the old drywall is a great idea, I'll definitely be doing that if possible. It's a lot of work, but it is the best way.
Terry,

A relatively easy way to do that is to cut the drywall flush to the edges of the stud bays using a reciprocating saw..... just be careful not to go any deeper than the back face of the drywall to avoid cutting any electrical wires (or other cables/pipes, etc.) that might be inside the wall... after that you can always leave the remaining strips of drywall on the studs. A bit of a trim on the edges and you are ready to reuse the drywall in the stud bays..

Having said that though I have to caution you.... you really might want to run that buy the local Fire Marshall first...

Although I do not know why this might affect the fire rating of the wall assembly - here in the states the code requirements are that the assembly be "rated and tested" - and I have never seen a rated tested assembly that was constructed in that manner.... meaning a layer of drywall installed within a stud bay. Some Fire Marshall's (and some insurance companies) might view that as a modification of the assembly that is not acceptable)

However I do know one thing (for a fact) and that is that you can't put insulation inside of the wall cavity of any rated/tested wall assembly if the test report does not specifically indicate that you can..

There are a number of assemblies where this is the case.... the reason for that being that the rate of heat buildup inside of a wall cavity is greater (by which I mean the buildup of heat in the assembly occurs at a quicker rate) in walls with insulation than in walls without insulation........

Rated assemblies have time elements involved - and if the assembly was not tested with insulation in the cavity it might well fail at containing a fire (in the zone of interest) if this aspect of it is altered....... or even if the insulation placed within the cavity is of a different thickness or density....... so this is something you really want to look into before acting - do not assume anything.

Quote:
So is there any way to do this while leaving the current firewall in tact? Is beefing up the middle layer an option, (now I just sound lazy) or would the three leaf wall be too much of a compromise? Also would I need to attach a ceiling to my new wall structure to isolate the roof?
Listen - reality is that sometimes we just have to live with the hand we're dealt..... and in instances where that is the case we look to overcome the obstacles we face....

Although the best situation would be a 2 leaf assembly - you can always leave the existing in place (with no modifications whatsoever) and overcome the situation strictly by installing additional mass on the inside face of a new isolated wall assembly........ anything can be made to work even in those cases where the starting point is not idea.....

Having said all of that my best suggestion to you would be to hire someone who knows the local codes and pay them for a consultation as to what you can/cannot do in regards to this property.... and in saying this something else comes to mind - you just said that you'll be "purchasing the bay" - this suggest to me that the property is actually a "commercial condo" - and if that is the case then you will also have to look over your condo documents......

In a typical condo the "ownership" of the property is from the "unfinished face of wall to unfinished face of wall. and the unfinished surface of floor to the unfinished surface of ceiling.

The interstitial spaces in between those surfaces and adjacent spaces, the concrete slab and the ground beneath it - and the space between the unfinished face of ceiling and the top surface of the roof are not owned by the owner of the unit but rather by the condo association - and as such you have no right (without their expressed permission) to remove anything or alter those assemblies in any manner.

So just make sure you walk through everything before you take any action whatsoever...

Rod
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sloper
Thread Starter
#7
24th June 2013
Old 24th June 2013
  #7
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Thread Starter
Quote:
Originally Posted by Rod Gervais View Post
Thanks for the kind words..... (by the way - it's Rod not Rob )

In a typical condo the "ownership" of the property is from the "unfinished face of wall to unfinished face of wall. and the unfinished surface of floor to the unfinished surface of ceiling.

The interstitial spaces in between those surfaces and adjacent spaces, the concrete slab and the ground beneath it - and the space between the unfinished face of ceiling and the top surface of the roof are not owned by the owner of the unit but rather by the condo association - and as such you have no right (without their expressed permission) to remove anything or alter those assemblies in any manner.

Rod

Hi Rod, (haha, sorry about the misspelling.) Turns out you are right about this ^^^. Altering the firewall is not one of my options, so I'm going to have to build a new wall in front of it. After quite a bit of reading I'm thinking of trying this.

Current fire wall -> 3" air gap -> Studs / Insulation -> 5/8 Drywall -> Quiet Glue -> 5/8 Drywall


And surrounding the drum area I would like to try this to save some space. (although I'm not sure about moving the drywall of my new wall closer to the original fire wall)

Current fire wall -> insulation -> 5/8 Drywall -> Quiet Glue -> 5/8 Drywall -> Studs with broadband absorption in between.


I will also make sure to laminate the drywall together when using the quiet glue and not screw the second drywall board into the studs.


I'm estimating the entire wall assembly to have an STC rating of ~ 55 (factoring in human error and a little luck). I'm not sure how it will handle live drums, or if I need to do more than this, but if anyone sees any red flags I'd love to hear it! :^)


Many Thanks!

-Terry
#8
24th June 2013
Old 24th June 2013
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jhbrandt's Avatar
 

Quote:
Originally Posted by sloper View Post
....I will also make sure to laminate the drywall together when using the quiet glue and not screw the second drywall board into the studs.
Terry,

Everything looks good except for the above. The Quiet Glue is NOT glue. It is a CLDM like Green Glue. Constrained Layer Damping is very good at what it does and is not affected by penetrating screws. Besides, what would you do if you had to put it on the ceiling like that?

So, go ahead and screw the system together. Be sure to stagger the drywall joints so that NONE are in the same place.

I highly recommend using 24" centers for your framing. This will provide your partition with a lower resonance frequency.

NOTE: If you use a 3" gap and 2 X 4 studs your effective air space will be 5 1/2".. if you use 2 X 6s it increases to 8 1/2". Doubling or tripling the air space, when you can afford to lose the space, is a very effective way to increase the Sound Transmission Loss. Also, you could simply add another 5/8" drywall board as well.

Cheers,
John
#9
24th June 2013
Old 24th June 2013
  #9
sloper
Thread Starter
#10
24th June 2013
Old 24th June 2013
  #10
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Thread Starter
Quote:
Originally Posted by jhbrandt View Post
Terry,

The Quiet Glue is NOT glue. It is a CLDM like Green Glue. Constrained Layer Damping is very good at what it does and is not affected by penetrating screws. Besides, what would you do if you had to put it on the ceiling like that?
John
It would make for an interesting day. The plan was to use type G laminating screws to secure the second sheet onto the first.

Three sheets of drywall seems like a good idea in the drum area and so does 2x6 framing. I'm worried about shaving more space from my room but really it's nothing when you consider the consequences of not having enough isolation. Drywall is also super cheap here in Canada.
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