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» ICC Bulletin Board » Code Chat » Building and Residential Codes -- Non-Structural Issues » t-bar (ACM7 seismic clip)

   
Author Topic: t-bar (ACM7 seismic clip)
mayjong
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anyone allowing this?
if so what is the function of this clip?
what standard bracing/tying/fastening details do this clip replace?

thanks!

Posts: 547 | From: Sacramento CA | Registered: Mar 2007  |  IP: Logged
Mark Randall
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Is this similar to the Armstrong Berc-2 clip?

The jurisdictions I do work in allow the Armstrong clips (I'm in seismic zone D, but it's good for E & F as well). I do not specify anything else as I do not want a 2" grid at the perimeter of my rooms. See ESR-1308.

Update: I did a google search and found that this is Donn's clip similar to the Armstrong Berc-2. The only question I would have is if Donn has done the testing and have an ESR approval like Armstrong has done. If so, I would urge you to consider accepting the product.

[ 10-07-2008, 04:12 PM: Message edited by: Mark Randall ]

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NJCode
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USG has their own website dedicated to seismic ceiling requirements. Has everything broken down into seismic zones.
"http://www.seismicceilings.com/"

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Building Official in Central NJ

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mayjong
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Mark-
so the clip you are allowing only replaces the 2" perimeter grid requirement?

this is the way i see it, too

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mayjong
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the reason i ask,
some installers (and jurisdictions ) around here, claim the verbage "meets or exceeds all national code requirements with 7/8 inch wall moulding" included in the submittal sheet (provided by the manufacturer) includes the requirement for compression struts!
in other words "if you use these clips, no compression struts are needed"!!!
in fact, i know of one jurisdiction in the area that requires the installer TO REMOVE compression struts when these clips are installed!!
am i that far behind the curve on this one???

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Mark Randall
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Yes,
This is an alternate to the 2" perimeter edge requirement. At least with the Armstrong system, there is a separate detail depending on whether you are on the "attached" edge or the "unattached" edge (uses same clip for both conditions).

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Mark Randall
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I didn't see your latest post before responding.

We have still been installing compression struts. I looked over Armstrong's approval and I don't see any mention about compression struts being required and they are quite detailed in the requirements. That would be a good question for the manufacturer (Donn in this case) as to what the intent is. I don't know.

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miguele3
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I've been using the BERC 2 system in California and other D,E,F locations and still with compression struts.

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Miguel

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Builder bob
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The Berc clip only replaces the requirement for the 2" wide molding, all support sprays, compression structs, isolation joints are still required. For clarification see the es report.

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mayjong
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thanks Bob!
that does it, sometimes you have to show it in writing!

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miguele3
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According to Armstrong if you use the BERC 2 on all four walls you don't have to use the stablilizer bars to prevent the main beams and cross tees from spreading. I guess the logic is because the entire diaphragm works together.

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Miguel

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Builder bob
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Wrong, the ES report sums it up nicely...... BTW, do you have a hardwritten copy of the report that states that or is it a salesman blowing smoke?

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mayjong
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miguele is correct , if by "stabilizer bars" he means the requirement for spreader bars (that keep the mains from spreading, you can also use tie-wire)
the contractor i was dealing with (and another local AHJ , too) was claiming the clips replaced compression struts , too.
the way i see it, (and the way ICC sees it, according to the report) the clips prevent "spreading" of the mains and cross "t"s -all on the horizontal- (therefore replacing the requirements for 2" wall mould, and spreader bars)
they do not replace vertical bracing (compression struts), or any other required bracing.

the other AHJ , was actually REQUIRING installers TO REMOVE compression struts that were already installed , when these clips are used...

[ 10-10-2008, 09:34 AM: Message edited by: mayjong ]

Posts: 547 | From: Sacramento CA | Registered: Mar 2007  |  IP: Logged
miguele3
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I have an Armstrong brochure that says you can eliminate the stabilizer bars at the perimeter if you use the BERC 2. This is not to replace the seismic separation joint at 2,500 SF but Armstrong has something called a "Seismic Joint Clip" for this function.

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Miguel

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mayjong
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agreed , the stabilizer/spreader bars and the 2" moulding are not required if the clips are used.
thanks!

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Bob Delaney
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I just attended a presentation that USG's technical folks gave to our association and their ACM7 clip can be used with 7/8in. molding / replacing the 2in. angle. Their clip also replaces the stabilizer bars because it prevents the perimeter tees from sliding side-to-side. They have an ESR report (ESR-1222) and have done tons of testing. Seismic separation joints and bracing is sill required. Overall the presentation was interesting.

Bob

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