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Gypsum Board Area Separation walls as fire walls

T

Tim Mailloux

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Hartford CT
We have a large apartment complex in design that will need to be divided with multiple fire walls due to the size of the building. The designer doesn’t want to go with freestanding, aka cantilevered CMU fire walls, and has been convinced by the structural engineer that we can use a Gypsum Board Area Separation Wall instead. In my research I see that gypsum area separation walls were intended to be used as party walls for town home construction and I have several concerns using them in a large scale 4 story apartment complex.

1. These area separation / firewalls will bisect common corridors and be used as horizontal exits with rated door openings in them. I cannot seem to find anything that allows for openings in this type of wall. A 2011 version of the Gypsum Association document GA-620 specifically states that penetrations and opening are not permitted in Gypsum Area Separation walls, while a newer 2019 version of the same document simply states that openings in these types of walls is not addressed in this document. Further more I am not convinces that a door installed in one of these walls would remain intact if one side of the wall collapses.

2. The IBC doesn’t seem recognize Area separation walls, and 706.2 Structural Stability lists NFPA 221 as the referenced standard for fire walls and NFPA 221 does not address Area separation walls. The IBC code commentary to 706.2 does mention Area separation walls and References the Gypsum Association Fire Resistance Design Guide but also states that these types of walls ‘have been accepted as fire walls’ which leads me to believe its up to the discretion of the AJU.
 
I just had a converation with technical services at the Gypsum Association and there stance is that openings or penetrations of any kind are not allowed in these types of walls.
 
Tim Mailloux said:
I just had a converation with technical services at the Gypsum Association and there stance is that openings or penetrations of any kind are not allowed in these types of walls.
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That is pretty foolish...it's just shaftwall..Guess they will be selling a lot less of that.....Gyp shafts not being allowed will change their tune pretty quickly.
 
UL Design No. U336 is commonly used for fire walls in Type V construction, including where crossing corridors. It still shows the term Area Separation Wall in the drawing as of the January 11, 2019 version.
 
Even 3-hour shaft liner walls are now being accepted for fire walls in Type III construction, based on UL Design No. W454.
 
Although there is no code prohibition for use of gypsum wall assemblies such as UL U336, I've always tried to pursuade the design professionals to use CMU walls instead of the gypsum. I do this because, in my experience, the carpenters building wood frame construction are typically not very well versed in commercial construction techniques, especially when it comes to continuity of fire-resistance rated assemblies. Continuity seems to be much easier for the contractors when CMU walls are used. (FWIW, we have had marginal success in getting CMU instead of gypsum.)
 
Tim Mailloux said:
I just had a converation with technical services at the Gypsum Association and there stance is that openings or penetrations of any kind are not allowed in these types of walls.
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Interesting
Table 716.1(2) OPENING FIRE PROTECTION ASSEMBLIES, RATINGS AND MARKINGS
Does allow door openings.
In the code, where does it say door openings "...not allowed in these types of walls...."
 
mark handler said:
Interesting
Table 716.1(2) OPENING FIRE PROTECTION ASSEMBLIES, RATINGS AND MARKINGS
Does allow openings, in the code, where does it say "...not allowed in these types of walls...."
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it doesnt say it in the code. This was according to a phone / email conversation I had with the National Gypsum Association with is the reference standard for the type of construction. Per that call / email it was stated that these walls were developed / designed to be used as party / fire walls between town homes and condos and were not designed or tested to have penetrations in them. The individual with National Gypsum also agreeed with me that it was not likely that a door could be attached to one of these assemblies and remain in place if one side of the wall collapsed in a fire.
 
Tim Mailloux said:
it doesnt say it in the code. This was according to a phone / email conversation I had with the National Gypsum Association with is the reference standard for the type of construction. Per that call / email it was stated that these walls were developed / designed to be used as party / fire walls between town homes and condos and were not designed or tested to have penetrations in them. The individual with National Gypsum also agreeed with me that it was not likely that a door could be attached to one of these assemblies and remain in place if one side of the wall collapsed in a fire.
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See Photo Attached to my post
 

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To revive this post with some additional questions: I have a proposed 5-story, III-A, R2 using a bearing ASW 2600 to create two buildings with a horizontal exit due to area limitation. I originally noted this as a deficiency per IBC 706.3 since it was a wood framed wall. The response is that the 2 layers of 1" type X constructed with H-clips is the actual fire wall, and that the wood framing is there only to support the gypsum panels. I see the logic with the burn-away clips but does it make the wood studs wall "supporting" the gypsum an interior wall not subject to the required non-combustibility? They also respond by basically saying "we can use it because it is referenced in GA 600". I find this irrelevant, because a wood frame fire wall is permitted in type V construction, so just because it is in the GA manual, doesn't mean it can be used anywhere. So the concerns here are structural independence and combustible construction.

I came up with the same info as the OP, but I don't have the 2018 GA 600. Is the prohibition of openings still in the GA 600-2018? The use of a HE would then be a problem, but even if not prohibited, can the single door frame (double egress) span across the opening? Which wall would it be attached to, and if that wall collapsed do we not now have a gaping hole in our fire wall? I also have the GA 620-2019 document that limits the ASW to 2-hrs and 4 stories, non-load bearing, and not as shear walls, ALL things the proposed design do not adhere to. The limitations listed on that document specifically say that the gypsum area separation walls are specifically designed to be 2-hr wall separating townhouses and areas in various occupancies. Would an R2 be a "various occupancy"? It does seem that these walls were designed for townhomes, not 5-story R2's, but there really isn't any restriction I see in the GA manual (I only have the 2009).
 
Thanks for the link, I downloaded The Wood Book, unfortunately it doesn't answer any of the questions. I will contact tech support at GA to try to straighten out the conflicting info.
 
I believe the gypsum area separation wall has to be attached to the wood stud walls on both sides with special aluminum clips. These clips melt on the fire side but still attach the gypsum to the wood studs on the non-fire side, so that it remains standing.
 
This one is the gift that keeps on giving.

I spoke with technical resources, they said the same things as already articulated. Not bearing, not shear, no openings, old design for townhomes...
I got a '21 GA-600, and the only thing it says is no openings, I also got The Wood Book, which does show a method for placing an opening into a 3-hr ASW, but not ASW2600, which is different from the assemblies they show in The Wood Book.

The response (again) from the DP is that the wood framing is not part of the assembly, therefore it is an interior wall and allowed to be combustible, and since it is not part of the assembly it can be load-bearing and used for shear. I understand the theory. In the new edition of GA-600 ASW2600 there is new language not shown in my previous editions (not sure when it was added) that says the following:

"Where required for structural support lateral bracing walls constructed with steel or wood studs and 1/2" gypsum panels (shown in detail with dashed lines)." (The illustration clearly shows the 1" gyp and mineral fiber in solid lines and the wood studs and gyp in dashed lines.)

This new language, though it has some curious sentence structure, seems to support that theory. Since it was not in previous versions of GA-600 I surmise it was added because someone else asked these questions.

So if we accept the interior wall/combustible issue as OK, and we accept the lateral bracing walls as not part of the rated assembly so they can be bearing and shear walls as OK, we are now down to 'are openings permitted?'.

GA-600 very clearly says no:
"Openings and through-penetrations, including protected openings and penetrations, are not permitted in the area separation fire walls contained in this manual".
However, The Wood Book clearly illustrates how to install an opening in a 3-hr ASW basd on a UL454. So I am skeptical of the statement, though I don't think I have a choice but to accept it. I would note that the opening shown in the W454 assembly makes sense, but it is different than ASW2600 and doesn't work as drawn.

ASW2600 is based on a 1982 fire test, WHI-495-0393. I can't find any information about that test, which may explain why the GA rep snickered a little when I brought it up.

If I am reading this situation wrong please chime in.
 
Any reason you keep focusing on ASW which is not an IBC term?...Is it an actual tested assembly? Does it meet the IBC requirements for firewalls? 706.2, 4 , and 5 specifically? 3 you can debate....
 
steveray said:
Any reason you keep focusing on ASW which is not an IBC term?...Is it an actual tested assembly? Does it meet the IBC requirements for firewalls? 706.2, 4 , and 5 specifically? 3 you can debate....
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ASW (area separation wall) is the proper name for an assembly type out of the Gypsum Association's GA-600 Design Manual.

Yes, ASW are actual tested assemblies; hence, they are published in the GA-600.

Yes, they can meet the IBC requirements for firewalls were constructed per the requirements of the listing and the Design Manual.

The root of the issue is in 706.2. ASW being light weight framing (shaftliner and H-studs w/ aluminum clips), they are not self supporting. Hence, the very specific prohibition on openings or penetrations through ASW.
 
I don’t remember exactly, but I think that 1982 WHI test of the GA ASW 2600 assembly was a non-loadbearing panel.
 
It is not me that is focused on ASW2600, it is the DP. I have raised several issues regarding it's use and the DP is still insisting on it. First, I said it needed to be non-com, his answer was that the fire rated assembly does not include the wood framing and is made up of the H studs and shaft-liner, which is non-com. I also raised the non-load bearing, non-shear and structural independence issues, which again they argued the wood studs are not part of the actual rated assembly and the H-studs and panels do not bear any load, and the melt-away clips take care of the independence issue. These issues were confirmed to be accurate by GA technical support, and in the '21 GA-600 manual they have added language that seems to support this. (The shear issue confuses me because the clips would not melt away in a non-fire event, but I suppose a shear issue is not a fire issue) I also said no openings are permitted by specific language in GA-600, which they have ignored each time. I believe there are assemblies that will work for them, that allow openings, that aren't too different from what they propose, that are not subject to the GA opening restriction, but they area apparently married to this one.

I have tried to find a path to the approved use of this assembly but the openings issue is preventing it.

Now, I have another issue that I didn't catch before. GA-600 is an approved method for determining prescriptive compliance for a rated assembly per the IBC (table footnotes). However, it jumped out at me today that only "generic" GA assemblies are permitted for prescriptive compliance. Am I reading then that the "proprietary" assemblies are not permitted? Or just not permitted as prescriptive (703.3 #2), and we could therefore revert to the listed assembly fire test (703.3#1) used for the GA assembly? I think that is the case but the issue there is I can't find any info on the referenced fire test from 1982, and am thinking it may not be of any help anyway since it was specifically geared towards use in townhomes.

GA-620-19 is a resource document that lays out uses and limitations for GA ASW assemblies. This document limits the walls to non-bearing, but then in the illustration shows the wood studs can be bearing. It is specific to townhomes, but adds "other attached dwelling units", does not intnd the use as shear walls, limits them to 4 stories, limits them to 2 hours. None of those things are shown in the ASW2600 design. IF GA-620 is a document meant ONLY for townhomes it would make sense, but the "other attached dwellings" kind of implies the criteria in the document apply everywhere.

I think this whole thing is a mess.
 
classicT said:
The root of the issue is in 706.2. ASW being light weight framing (shaftliner and H-studs w/ aluminum clips), they are not self supporting. Hence, the very specific prohibition on openings or penetrations through ASW.
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706.2 says nothing about self supporting, just allowing collapse on either side....
 
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