any of you practitioners out there have knowledge of two-hour wall assemblies using wood studs that use something other than 2 layers of 5/8 gyp on either side?
like is oft' the case i have a two hour wall meeting a one hour wall in the same plane and i'm looking for a way to keep them as close to flush as possible w/o furring out the other wall to match.
book references, web references, ul or wp #s please.
2″ × 4″ wood studs 16″ on center with metal lath and 7/8″ neat wood-fibered
gypsum plaster each side. Lath attached by 6d common nails, 7″ on center.
Nails driven 11/4″ and bent over.
1-hour wall finished face to face = 5.5"
2″ × 4″ wood studs 16″ on center with two layers 1/2″ regular gypsum wallboarde
applied vertically or horizontally each sidek, joints staggered. Nail base layer
with 5d coolern or wallboardn nails at 8″ on center face layer with 8d coolern or
wallboardn nails at 8″ on center.
as a sidenote about alternate fireproofing, check out shigeru ban's highrise in osaka - plywood was used as fireproofing around the columns
and to support his claim of a 'fireproof' wood, the results from tests show that the wood reached a charcoal state and stopped burning at a certain point. i'm not sure of the specifics, but there is some detailed info in his phaidon monograph.
There are fire-treated plywoods. We did a boathouse below the floodplain and had to use some as a finish material since gyp. bd. & plaster are not allowed. I understand they are made with some nasty chemicals like arsenic and formaldahyde, although I think some eco alternatives have come out in the last few years. What you're talking about sounds like the theory behind heavy timber construction.
Could someone pass me the UL Design No for a 1 hr exterior wall. Ideally looking for a 5/8" gyp interior, 2x6 stud and 7/16" OSB exterior; or something close; perhaps need another layer of gyp under the OSB?
existing 2x6 wall is sheeted with 7/16 OSB any way to achieve a 2hr rating without having to remove sheeting. 3 layers of 5/8 typ x gyp on the inside?
Dec 16, 19 8:12 pm ·
·
Non Sequitur
What does your architect say?
Dec 16, 19 10:26 pm ·
·
archanonymous
3 layers of gyp is definitely not the answer
Dec 16, 19 10:53 pm ·
·
atelier nobody
2019 IBC Table 721.1(2)
Dec 18, 19 2:20 pm ·
·
threeohdoor
Genuinely Curious Devil's Advocate: Why is 3x Fireshield on either side"definitely not the answer"? UL lists 2x4 assemblies with 2x both sides for 2hr ratings.
Dec 18, 19 2:46 pm ·
·
Non Sequitur
^It depends on the situation. Is Joe's 2hr wall a fire separation between 2 suites? If so, laminating gypsum board to one side will not work since the supporting structure (2x6 studs) are unprotected on one side of the assembly. There are not many ways to achieve rated partitions using a one-sided membrane approach. Perhaps you American cowboys have more flexibility, but unless I use a prescriptive ULC assembly, I am limited to 2 layers of 1/2" gypsum board (and 90min) when designing rated walls as per my building code.
Dec 18, 19 2:59 pm ·
·
atelier nobody
Many years ago, there used to be some situations in the Code that allowed for a 1-sided assembly, but I honestly don't know whether or not they're still in there, as I've never used one.
Dec 18, 19 3:06 pm ·
·
Non Sequitur
^they're called shaft walls now.
Dec 18, 19 3:17 pm ·
·
threeohdoor
Ah, yea, I just assumed he was laminating both sides. In the case of asymmetric walls, NYC considers rating the "thin" side as the rating for the assembly. I suppose he'd have to build a shaft wall in front of the OSB and run it horizontally to exterior/demising walls. As for more than two layers each side for a rated wall, I can't honestly say that I've had to do so. I've done super thick isolating walls for acoustic reasons, but that was internal to a space.
Dec 18, 19 3:57 pm ·
·
atelier nobody
A shaft wall is asymmetrical, but it still has protection on both sides.
Dec 18, 19 4:41 pm ·
·
Non Sequitur
Sorry, I should have added a /s to my shaft wall comment.
two-hour wood wall assembly help
any of you practitioners out there have knowledge of two-hour wall assemblies using wood studs that use something other than 2 layers of 5/8 gyp on either side?
like is oft' the case i have a two hour wall meeting a one hour wall in the same plane and i'm looking for a way to keep them as close to flush as possible w/o furring out the other wall to match.
book references, web references, ul or wp #s please.
thanks.
2-hour wall finished face to face = 5.5":
2″ × 4″ wood studs 16″ on center with metal lath and 7/8″ neat wood-fibered
gypsum plaster each side. Lath attached by 6d common nails, 7″ on center.
Nails driven 11/4″ and bent over.
1-hour wall finished face to face = 5.5"
2″ × 4″ wood studs 16″ on center with two layers 1/2″ regular gypsum wallboarde
applied vertically or horizontally each sidek, joints staggered. Nail base layer
with 5d coolern or wallboardn nails at 8″ on center face layer with 8d coolern or
wallboardn nails at 8″ on center.
As jh:
...
UL Fire Resistance Directory:
Design No. U301, U334, U350, U357
Double up on the 1-hour wall and just make it a 2 hour wall. Shouldn't cost too much more.
second that
You cold also stager the studs ( ½â€) in the 1hr wall, but labor wise it would be easier just to double up the drywall.
treble the doubling.
as a sidenote about alternate fireproofing, check out shigeru ban's highrise in osaka - plywood was used as fireproofing around the columns
and to support his claim of a 'fireproof' wood, the results from tests show that the wood reached a charcoal state and stopped burning at a certain point. i'm not sure of the specifics, but there is some detailed info in his phaidon monograph.
There are fire-treated plywoods. We did a boathouse below the floodplain and had to use some as a finish material since gyp. bd. & plaster are not allowed. I understand they are made with some nasty chemicals like arsenic and formaldahyde, although I think some eco alternatives have come out in the last few years. What you're talking about sounds like the theory behind heavy timber construction.
Could someone pass me the UL Design No for a 1 hr exterior wall. Ideally looking for a 5/8" gyp interior, 2x6 stud and 7/16" OSB exterior; or something close; perhaps need another layer of gyp under the OSB?
Thanks.
Pretty useful wall selection widget from USG:
http://www.usgdesignstudio.com/wall-selector.asp?utm_source=Home+Page&utm_medium=direct&utm_term=wall-selector&utm_content=logolink&utm_campaign=Launchpad
Very handy UL assembly search page that I have been using for a number of years. It has recently be revamped to be a little more user-friendly.
http://database.ul.com/cgi-bin/ulweb/LISEXT/1FRAME/FireResistanceWizard.html
Thanks for the sites and links. I appreciate the help.
existing 2x6 wall is sheeted with 7/16 OSB any way to achieve a 2hr rating without having to remove sheeting. 3 layers of 5/8 typ x gyp on the inside?
What does your architect say?
3 layers of gyp is definitely not the answer
2019 IBC Table 721.1(2)
Genuinely Curious Devil's Advocate: Why is 3x Fireshield on either side"definitely not the answer"? UL lists 2x4 assemblies with 2x both sides for 2hr ratings.
^It depends on the situation. Is Joe's 2hr wall a fire separation between 2 suites? If so, laminating gypsum board to one side will not work since the supporting structure (2x6 studs) are unprotected on one side of the assembly. There are not many ways to achieve rated partitions using a one-sided membrane approach. Perhaps you American cowboys have more flexibility, but unless I use a prescriptive ULC assembly, I am limited to 2 layers of 1/2" gypsum board (and 90min) when designing rated walls as per my building code.
Many years ago, there used to be some situations in the Code that allowed for a 1-sided assembly, but I honestly don't know whether or not they're still in there, as I've never used one.
^they're called shaft walls now.
Ah, yea, I just assumed he was laminating both sides. In the case of asymmetric walls, NYC considers rating the "thin" side as the rating for the assembly. I suppose he'd have to build a shaft wall in front of the OSB and run it horizontally to exterior/demising walls. As for more than two layers each side for a rated wall, I can't honestly say that I've had to do so. I've done super thick isolating walls for acoustic reasons, but that was internal to a space.
A shaft wall is asymmetrical, but it still has protection on both sides.
Sorry, I should have added a /s to my shaft wall comment.
IBC limits calculated resistance with wood studs to 1hr. All 2hr wood studs assemblies I am aware of are two-sided.
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