Exterior wall, width limited. What do you think?

How thick should my walls be, should I float my floors (and if so, how), why is two leaf mass-air-mass design important, etc.

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cadesignr
Senior Member
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Joined: Mon Mar 03, 2003 4:25 pm
Location: Oregon USA

Post by cadesignr »

Hello Gents.....quick relative question Steve. Is there anything that says you CAN NOT use a layer of 5/8" drywall BEHIND the OSB on an exterior wall, IF you use a visqueen layer between the two? Woudn't that increase the mass of the exterior leaf? Just a thought.
fitZ :?
alright, breaks over , back on your heads......
knightfly
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Location: West Coast, USA

Post by knightfly »

Rick, not sure about the gyp behind sheathing yet; will try to find time tonight at work to check the IBC on this; meantime, I'm still digesting stuff on vapor barriers and all the misinformation and WRONG code rules, etc - here's one reason why -

http://irc.nrc-cnrc.gc.ca/cbd/cbd175e.html

Michael, here's the link to that freebie Insul calculator; the real one costs over $1000, but is 'way ahead of the old demo. Still, lotta bux if you're not doing this professionally. Oops, lost it; I'll post it later when I have time -



I'll come back to this tomorrow nite after I'm out of the coma... Steve
Michael Lee
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Joined: Fri Oct 29, 2004 10:42 pm

Post by Michael Lee »

Michael, here's the link to that freebie Insul calculator; the real one costs over $1000, but is 'way ahead of the old demo. Still, lotta bux if you're not doing this professionally. Oops, lost it; I'll post it later when I have time -
I found the demo but the version I have doesn't allow me to change the Gypsum Board to anything else. It's crippleware. You must have an different demo version... Oh well. Actually, I start my new position as Project Manager tomorrow so I might get the 30-day demo through my new firm if the boss is okay to the idea. I think that would be a great tool to have around anyway with all the AV rooms in these high end homes.

Thanks for everything Steve... Michael Lee - Draftsman
AVare
Confused, but not senile yet
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Location: Hanilton, Ontario, Canada

Post by AVare »

I found the demo but the version I have doesn't allow me to change the Gypsum Board to anything else.
You can change the physical properties of the material to effect concree etc.

Twisted thinking:
Andre
knightfly
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Joined: Sun Mar 16, 2003 11:11 am
Location: West Coast, USA

Post by knightfly »

Sorry, didn't have time to explain some of the "tweaks" - if you click on Material Constants, you can change the density from 690 to about 2000 - then, change the layer thickness to whatever amount of concrete you want to simulate; the results are within 1-2 dB of published results for concrete walls. You will NOT get the same results by just adding 12.5mm layers to get 6" of material.

IF you drop the density from 690 down to about 600, you can model plywood fairly close. Be sure and change the panel size at the top of the window; it's set pretty large, and will affect results. I usually set this to 1.2 x 2.4 meters.

You can't change the insulation type, so you're stuck with that; you can do two different materials per side of the wall, but only one layer of one and several layers of the other. Doing this, you can approximate using a layer of 1/2" wallboard between two 5/8; only it will look like the 1/2" is on one side of the two thicker layers - the coincidence graph will still reflect the changes.

The setting for steel studs is apparently calculated for NON-structural, or 25 gauge, studs; it returns essentially the same result as resilient mounting, and the only reason this would be true is if you used the lighter more flexible studs.

There are probably a few other tricks I've either not found or not remembered; if you want more, you can always cough up $1200 for the full newer version; they've discontinued the personal version that used to be about $200. I asked Keith at Marshall-Day if they intended to produce a new personal version, and he said they didn't think so.

Hope that helps... Steve
Michael Lee
Posts: 16
Joined: Fri Oct 29, 2004 10:42 pm

Post by Michael Lee »

There are probably a few other tricks I've either not found or not remembered; if you want more, you can always cough up $1200 for the full newer version; they've discontinued the personal version that used to be about $200. I asked Keith at Marshall-Day if they intended to produce a new personal version, and he said they didn't think so.
Daggone greedy Aussies. I guess too many sound engineers were opting for the lesser cost version. I wonder how many $1,200 packages they'll sell in comparison? We'll tinker with the values. Thanks again! Michael Lee - Draftsman
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