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PostPosted: Tue Sep 08, 2020 9:33 am 
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Location: Orange, Australia
John
Thanks for your thoughts on the 2nd leaf ceiling..timely as once i settle the middle frame i can get back to that design. BTW, the 2 columns is really only because it matches their end frames which makes it a standard product which is warranted by the supplier against code here.
Once I have settled things this week i'll be posting a revised design and pick up on the HVAC design elements we discussed on your blog
Andrew


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PostPosted: Thu Mar 04, 2021 9:39 pm 
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Location: Orange, Australia
Hello everyone!

Long time since my last post - due to a rethink: not the layout or inner rooms’ construction nor concrete base, but a rejig of the outer wall construction. It’s still a “room in a room” per John Sayers.

For the outer wall, I’ve moved from cement blocks to a wood framed wall, clad on the outside with a 0.42mm Corodek (steel) skin and a 3 layer outer wall fixed to the inside of the studs – one layer of plywood/16mm Frychek (drywall) and 2 layers of 19mm yellow tongue (structural grade particleboard sheet).

Why change?
The cement blocks were going to be harder to DIY/more expensive and the more I searched the site, it gradually dawned on me that I could achieve similar isolation from this new wall design together with what I’d planned for the outer ceiling anyway – a 2x fyrchek outer ceiling with green glue between the ceiling layers.
The mix of ply and Fyrchek on layer one of the outer wall is due to engineering requirements to employ structural bracing of the timber frame at intervals with ply; rather than use the more expensive ply for the whole outer layer, I’m only using ply where I have to and fyrchek elsewhere on layer 1. The use of Yellow tongue particle board as the 2nd and 3rd layers for the outer wall is because it’s cheaper than Fyrchek. (I may still revert to layers 2 and 3 being Fyrcheck as the yellow tongue standard supply width means more joins/caulking than Fyrchek.)

I included sketchup images to hopefully help with explanations/context.

Attachment:
Overview.JPG

Attachment:
Overview 2.JPG

Attachment:
Overview open.JPG


While I’ve spent countless hours on research, there are probably some rookie errors in here somewhere so please don’t hold back in correcting me where any of my logic or design is faulted.

SPECIFIC QUESTIONS

1. Technically, I have a 3 leaf structure on the roof (as before) and now on the walls as well. Paulus87 replied to my initial post essentially confirming that this is more a technical observation than a practical concern - as relating to my initial design. My understanding is that the argument is that the outer skin (0.42mm steel) is of low mass (4.35kg/m2) and there is substantial airflow between it and the first layer of isolation – therefore it can be ignored in practice. Q; Please let me know if that conclusion is faulted given that the steel skin and the first layer of the outer wall is NOW only separated by 90mm – the width of the studs. I’ve included below a close up of the wall construction to help.

Attachment:
Wall structure.JPG


2. My studio is in fact a wood frame structure built under a steel “hay shed”. Since dropping the cement block wall concept I’ve spent hours designing how I’ll build my outer walls around the steel columns that support my roof (the pics below shows how I planned to construct the Ply/Fyrchek/particleboard layers around the columns – both the side and back columns together with some images of the framing). I’ve since wondered whether I am over engineering this. Steel is 10x denser than Fyrchek/drywall which made me think that I could use the steel in the columns as part of the outer wall – specifically, to butt the Fyrchek/particleboard layers up to the columns and use an acoustic sealant in the join between the Fyrchek/particleboard and the steel. (see final pic below) Q: Will the use of the steel column in this manner compromise isolation?

Attachment:
Back Column.JPG

Attachment:
Back Column side.JPG

Attachment:
Back wall frame.JPG

Attachment:
Side wall isolation.JPG

Attachment:
Side wall outside frame.JPG

Attachment:
Steel Column as part of isolation.JPG


3. The one area I could see as a vulnerability with the design above is that there is no staggered join where the Fyrchek/particleboard layers butt up against the column – if this is an issue I could adopt the following to provide some “insurance”. Q: is this worth it/necessary?

Attachment:
Alternative .JPG


Resolving this will settle the sizes of my rooms. Currently I have ~200mm between the inner and outer walls except where the boxing of the columns in my current design “pushes in”. If the steel can form part of the outer wall then it’s all cruisy…

Thanks again for sharing your experiences

Andrew

BTW - Paul, I have worked with my engineer and incorporated a layer of reflective foil laminate backed insulation used here to address the concerns you raised


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PostPosted: Sun May 23, 2021 8:30 pm 
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Location: Orange, Australia
Hi

I've been busy constructing the outer shell of the building the issues I've raised here have not got in the way of my plans .......but decision time is looming!

Anyone got any insights for me?

Andrew


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PostPosted: Mon May 24, 2021 1:19 am 
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it's not clear what your concerns are. you've created an outer shell with mass, damping, moisture control, and designed a decoupled inner pair of shells - presumably using properly size joists for the spans, and appropriate vertical framing to support a few tons of material overhead.

so that all looks good.

missing: HVAC plan including outdoor ventilation required for keeping people alive in a hyper-insulated set of rooms. and which should be wholly separate from the workshop to avoid noxious fumes, dust, etc (plus it's probably lower cost to keep that space temperature/humidity etc controlled. the HVAC in the studio must run fulltime when occupied.

doors windows etc all need to match isolation mass and be sealed. heavy doors need closers to ensure safety. recommend emergency light in rooms esp if no windows.

for more safety - consider what happens to occupants if the fire is in the workshop (probably more likely than say spontaneous combustion from a musician playing the God riff) how do you exit? fire suppression? alarms? etc. no one can hear you scream in a soundproof room...

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PostPosted: Mon May 24, 2021 11:15 pm 
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Glenn

Thanks for the feedback...looking back through my previous post I think I could have been clearer :oops:
Also I appreciate the safety perspective :D loss of power in a fully enclosed room would be fun!

I'll step through your comments and clarify my concerns at the end
gullfo wrote:
it's not clear what your concerns are. you've created an outer shell with mass, damping, moisture control, and designed a decoupled inner pair of shells - presumably using properly size joists for the spans, and appropriate vertical framing to support a few tons of material overhead.

Yep - the wall/ceiling designs are have all engineering sign-off.
gullfo wrote:
missing: HVAC plan including outdoor ventilation required for keeping people alive in a hyper-insulated set of rooms. and which should be wholly separate from the workshop to avoid noxious fumes, dust, etc (plus it's probably lower cost to keep that space temperature/humidity etc controlled. the HVAC in the studio must run fulltime when occupied.

Agreed - I was trying to break this down into chunks rather than do one large post. I'll post later on the HVAC plan in detail but for now my plan is to run a ducted mini-split in the space between the outer leaf ceiling and the metal roof with ducting and 4 outer wall silencers in the roof space between the outer ceiling and metal roof and the inner leaf silencers penetrating the inner room ceiling. I've done enough work on that to get comfortable that I can fit in my silencers in.
gullfo wrote:
doors windows etc all need to match isolation mass and be sealed. heavy doors need closers to ensure safety. recommend emergency light in rooms esp if no windows.

Yep - understood on doors - I've done some early work on that but need to hone in when I get to detailed framing design. Safety light - good call...sounds like the voice of experience
gullfo wrote:
for more safety - consider what happens to occupants if the fire is in the workshop (probably more likely than say spontaneous combustion from a musician playing the God riff) how do you exit? fire suppression? alarms? etc. no one can hear you scream in a soundproof room...

“Workshop” may be an overstatement of use...it’s really a man cave - workbench, beer production and storage of mowers etc. There won't ever be anyone using the workshop while the studio is in use but some more thought on fire safety/exit is worth a stop and think

To my concern
There are 5 points where I am using the part of the 2.4mm steel C section columns as part of the outer leaf but these columns also extend into the air gap between the outer and inner walls and extend above the outer ceiling. Two questions flow from this:

a. whether I am compromising my isolation at all by taking this approach; and
b. whether I need to measure the air gap between the inner and outer rooms from the drywall to drywall as you would with a drywall/wood stud construction OR measure it from the most inner part of the steel C-section

For now I'll just focus on the first question and I’ll use one of the columns on the side wall as an example- noting that I’ve changed my construction approach very slightly from the post you replied to – using some treated pine on the inside of the steel C-section:
Here’s some sketchup close ups showing the outer leaf consisting of drywall (Fyrchek here in OZ) butting up against the steel C-section
Attachment:
Mullion1.JPG
Attachment:
Mullion2.JPG

And one more showing how the steel C section column joins the outer leaf ceiling
Attachment:
Mullion outer celing.JPG

What is worrying me is whether the fact that the steel C-section column is
1. part of the outer leaf
2. extends to within the air gap; and
3. extends beyond the outer ceiling line
is problematic in terms of isolation - flanking is my worry here. Do I have anything to worry about or am I overthinking (or maybe underthinking it)?

Hope this is clearer than before!

Andrew


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PostPosted: Mon May 24, 2021 11:50 pm 
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yes much clearer - :)

on the column - as long as it's not part of the inner walls and ceiling, then there should be little problem. if you do connect it to the inner walls, ceiling, inner frame etc, then yes, you will have coupled them and thus loss a significant amount of isolation. if you need to stabilize the inner frame - isolation sway bracing is the answer - Mason Industries and Kinetics Noise have products to handle that requirement as well as detailed specs and drawings on using them.

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PostPosted: Tue May 25, 2021 6:17 pm 
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Glenn

Thanks for that - and for the advice on the stabilization solutions - I've yet to give detailed thought to the inner rooms but that will come in time

I'll admit I've been struggling with understanding flanking; when I was editing those pics in my last post and adding all the arrows with the sealant points it probably should have dawned on me that by leaving a small gaps at joins and filling with acoustic sealant I am decoupling from any of the structural elements that support the outer leaf :oops:

In terms of leaf 1 and 2 coupling, I've been at pains to ensure that there is absolutely no contact - my air gap objective is 200mm - based on the isolation needs.

That leads me to the question I left behind in the last post which is how to think about the steel C-section columns in relation to the air gap.
I know that the air gap is normally measured from leaf face to leaf face ie ignore the studs provided there is at least a 1" gap between the inner and outer leaf studs per pic below
Attachment:
gap 250521.JPG

Q; Am I right in thinking that I can apply this approach in relation to my steel C-section columns? - this would means the outer layer of my inner room needs to be at least 1" from the steel C section

Thanks again for your time and expertise

Andrew


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PostPosted: Wed May 26, 2021 12:32 am 
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the air gap is the depth of the wall (or ceiling) framing + the gap between framing of inner and outer rooms. effectively the mass-to-mass distance. so a 2x6 wall (at least in US) is 5.5" + 1" gap + 5.5" would be a 12" air gap. so you'd fill in that gap with 12-14" of soft insulation depending on the batts sizes available, probably better to squeeze a slightly thick amount of soft insulation to ensure full contacts with the mass layers/vapor barrier, etc.

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