# Fire-rated assemblies... are 2x4 walls interchangable with 2x6 walls?



## EnvisionMan

I am trying to call out a specific assembly (with James Hardi Plank siding, to be specific) and all the assemblies that work are shown with 2x4 stud walls.  The customer wants 2x6 walls.

Is there any sort of 'assumption' in place that says I can use the same assembly with a 2x6 wall that would work for a 2x4 wall?

If not, does anyone have any good suggestions for simple, 2x6 wood stud walls with concrete siding (hardi-plank)?

Thanks!


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## Builder Bob

What is the listing agency??

Sometimes the small words in front of the book provides additional info....


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## cda

EnvisionMan said:
			
		

> I am trying to call out a specific assembly (with James Hardi Plank siding, to be specific) and all the assemblies that work are shown with 2x4 stud walls.  The customer wants 2x6 walls.Is there any sort of 'assumption' in place that says I can use the same assembly with a 2x6 wall that would work for a 2x4 wall?
> 
> If not, does anyone have any good suggestions for simple, 2x6 wood stud walls with concrete siding (hardi-plank)?
> 
> Thanks!


you do know there is a weekly question limit????

There are some other sites that hopefuly others will post that you can punch in kind of what you want and it pops up listed assemblies::

http://database.ul.com/cgi-bin/ulweb/LISEXT/1FRAME/FireResistanceWizard.html


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## steveray

They typically are...BUT...you will find that info in the actual listing....


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## cda

http://www.usg.com/content/dam/USG/United%20States/Product%20Related/Interior%20Panels/Imperial%20Firecode%20C%20Core%20Gypsum%20Base/documents/language/english/Product%20Literature/usg-fire-resistant-assemblies-catalog-en-SA100.pdf

http://www.awc.org/Publications/dca/dca3/DCA3.pdf

http://www.americangypsum.com/resources/design-library/?submitted=1&n_supercat=1&n_rating=1+hr.&n_category=5&n_design_no=&submit=Search


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## JBI

Agree with the above. Check the listings in UL or the USG books. Exterior wall assemblies are often listed for either 2 x 4 or 2 x 6, but not always.


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## Paul Sweet

UL BXUV.GuideInfo - Fire Resistance Ratings - ANSI/UL 263 (in the UL Online Certification Directory) says "The size of studs are minimum unless otherwise stated in a Design" under VI. WALL AND PARTITION ASSEMBLIES.


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## EnvisionMan

As some of you might know (reading other posts I have submitted recently) I am drawing plans for an over/under duplex.  I have drawn more than a dozen side-by-sides with no problem calling out the fire-rated assembly that splits them.  But an over/under is a whole different story.  The most amazing thing in all of it is that I get tons of general advice (thank you) but I still have yet to hear from anyone that has actually DONE an over/under duplex.  It is like Bigfoot.

I have spent a great deal of time on the UL site.  I have looked at over 200 assemblies in the past few days.  A vast majority of them don't apply to construction methods for residential in our area (especially running metal channels along the ceiling and screwing the gypsum into those... no one does that in residences down here) so I didn't have a lot to choose from.  They do NOT say 2x4 or 2x6 walls.  They do not say "2x4 minimum" or anything.  However, in alignment with Paul's comments above, I have seen comments about "design criteria listed are minimums only" but it doesn't specifically call out studs.

I am using one of the simplest of assemblies... U309.  If you look at UL.com and use their wizard, you can see the stud callout is only 2x4.

Thank you all for your help.  I do appreciate it.  I told my wife last night that I felt like I was back in college... I have been learning more in the past couple weeks than I have learned in the past 5 years.  Brain overload, but grateful for the new understanding.  Than


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## georgia plans exam

I don't know if this helps but, If you were using an assembly from the Gypsum Associations Fire Resistance Design Manual, 19th edition, under the general explanitory notes-note #15 on page 9, allows greater stud sizes to be used.

GPE


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## north star

*& = & = &*





> "Thank you all for your help.  I do appreciate it.  I told my wife last  night that I felt like I was back in college... I have been learning  more in the past couple weeks than I have learned in the past 5 years.   Brain overload, but grateful for the new understanding."


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