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Discussion Starter · #1 ·
Hi guys, I'm looking for a table that shows the limiting heights for 2 hr fire rated wall, this is a interior partition, composite, 34' 8" avg. height, non-braced, with 2 layers of 5/8" type X fire code gypsum board on each side of the wall.

I found that 600S125-43 (33KSI) studs @ 16"OC, will meet the required height for 1hr assembly UL-419, which states that 1 layer of 5/8" gyp board on each side shall be used to meet rating.

I'm assuming that using and additional layer of gyp. on each side will make the structure stronger and the limiting height even higher, but I can't find any table of limiting heights for this type of wall that prove I'm correct:thumbup: of definitely wrong:huh:.

Does anyone here have build a similar wall, or know where I can find more information regarding the metal members I need to use to comply?

for your time, thanks in advance !

Oscar
 

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Discussion Starter · #3 ·
like I posted earlier, all information was given already.

no plans or specs, that's why I'm asking here, the owner is requesting us for a quote and we are only trying to figure out the materials we need to build a wall that meet the 2hr rating and the structural need for such height.

using ul-419 design, we comply with the fire rating by using 2 layers each side of wall, what I'm looking for is a TAble that shows me the limiting height of wall members on a 5#LPF, L-120, 35' max AFF.

according with 2 already reviewed tables the minimum member size for a wall with 1 layer of 5/8" gyp on each side, is 600S125-43 (33ksi) this will allow us to as high as 35'9", but not really sure if adding a second layer of 5/8" gyp will extend the limiting height or reduce it....

still googling here...
 

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Discussion Starter · #5 ·
20g 6" studs will only go 30'10" at 12"OC, that's why I think 18ga is the best choice, but again this is only for 1 layer not 2, I can't find a table that shows me 2 layers each size of wall limiting heights.:rolleyes:
 

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Discussion Starter · #10 ·
I don't mean to hijack this thread, but I'm curious how you manage the boards when hanging walls at that height. Scissor lift?
Yes, we use a 48" wide platform scissor lift that holds 2 persons and the weight of the board. Scaffolding would be very hard and a bit dangerous with a full board. Though we have done it where a scissor lift can't get in to the game, look at this pictue ...


this a four sets high of masonry scaffolding frames inside a huge 30' height house entry room. Was scary to hung those ceiling boards.
 

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Discussion Starter · #11 ·
Limiting height tables here but I would check with your supplier. I don't think the second layer of GWB changes the height limitations.

http://www.clarkdietrich.com/produc...stud-drywall-framing-system/technical-content
Thanks.

This table shows a max 6" studs 20ga @16"OC to be 33'3", we don't want to go 12"OC, that's why I believe going 18ga will give us the 35' we need, I saw that in other table, but again only one layer of 5/8" on each side was used on the chart, still can't find 2 layers tables...
 

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Yes, we use a 48" wide platform scissor lift that holds 2 persons and the weight of the board. Scaffolding would be very hard and a bit dangerous with a full board. Though we have done it where a scissor lift can't get in to the game, look at this pictue ...


this a four sets high of masonry scaffolding frames inside a huge 30' height house entry room. Was scary to hung those ceiling boards.
Why are you hanging the boards in that direction?
 

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Discussion Starter · #13 ·
Why are you hanging the boards in that direction?
convenience.

1.scaffolding orientation and
2.boards bent easier on the short size (4ft) than the large size(8ft).

It's like when doing tall walls, we apply drywall vertically to studs, just easier for us, we do 95% commercial work and that the way many engineers design these walls. Horizontal layout on many commercial project is just not allowed, not really sure why.
 

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convenience.

1.scaffolding orientation and
2.boards bent easier on the short size (4ft) than the large size(8ft).

It's like when doing tall walls, we apply drywall vertically to studs, just easier for us, we do 95% commercial work and that the way many engineers design these walls. Horizontal layout on many commercial project is just not allowed, not really sure why.
Because of the fire rating you would need continuous metal blocking on all factory edges. The steel stud on your flats gives you your rating. Also could you imagine topping off with lay downs!
 

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Discussion Starter · #15 ·
Because of the fire rating you would need continuous metal blocking on all factory edges. The steel stud on your flats gives you your rating. Also could you imagine topping off with lay downs!
Makes perfect sense, by laying gyp. vertically you minimize the voids exposure by having a continuous metal backing along the large edge.
Never really think about it, but you are right.:clap:
 

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look at this pictue ...


this a four sets high of masonry scaffolding frames inside a huge 30' height house entry room. Was scary to hung those ceiling boards.
I'm sorry, but that is not the right way to hang that ceiling. Boards should have gone the other way. And you also did not stagger the butt joints. IMO

And Welcome to the site. Stick around. :thumbsup:
 

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Thanks.

This table shows a max 6" studs 20ga @16"OC to be 33'3", we don't want to go 12"OC, that's why I believe going 18ga will give us the 35' we need, I saw that in other table, but again only one layer of 5/8" on each side was used on the chart, still can't find 2 layers tables...
I checked with one of architect "buddies" The number of layers on GWB doesn't have any impact on the allowable length of the framing members. She did say that each manuf. has slightly different span tables.
 

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Personally I have never heard of height limitations on fire wall as long as its covered with the right burn time.

Just curious what's the most number of layers everyone has hung on one side of wall? 4 for me was working on movie theater the walls between theatres 4 layers on each side. hitting other screws on bottom layers what a night mare. just thought I would share that
 

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Personally I have never heard of height limitations on fire wall as long as its covered with the right burn time.

Just curious what's the most number of layers everyone has hung on one side of wall? 4 for me was working on movie theater the walls between theatres 4 layers on each side. hitting other screws on bottom layers what a night mare. just thought I would share that
It's not a height limit on the wall, it's requiring a minimum size/gauge stud relative to it's length. Keeps someone from using 3 5/8" 25gauge on taller walls. Fire rating is more than just burn time, durabilty is part of the calculations. A fire hose can knock over a light gauge wall with a single layer of rock.

4 layers here, movie theater but they do it for sound not the rating. 3 layer of 5/8" on a three hour wall. all seams staggered 16"
 

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Discussion Starter · #20 ·
Thanks for the posts
6",18ga, is our choice based on dietrich spam tables, adding more layers will not affect the limiting height apparently.
Although I have seen tables that shows a higher limit on one side vs. both sides of stud being covered, and though that adding layers may increase height limit.

4 layers each side our max, at a theater also sound proofing was the application, stagered 24" vertically, 16" horizontally, per plans
 
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