# UL Fire Resistive Wall Assemblies



## Codegeek (Aug 23, 2011)

This may be a dumb question, then again, maybe not.  I have a wall which is required to be one-hour rated.  We have provided details on the plans for a U465 wall assembly.  I have had it engrained in me that you cannot add or subtract to a UL listing as now the assembly is no longer listed,at least not according to the one specified. So my question is can blocking of any kind, regular wood, fire retardant treated or metal, be allowed within the assembly?


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## rktect 1 (Aug 23, 2011)

I believe that it is allowed per section 603.  But if you don't want to add/modify a UL listed wall assembly, you can always change it to a wall assembly as shown in section 7 of the IBC.


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## brudgers (Aug 23, 2011)

Wood would not be appropriate, but just about every U465 wall ever built has blocking...which makes sense since blocking is a "framing member."  http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name=BXUV.U465&ccnshorttitle=Fire+Resistance+Ratings+-+ANSI/UL+263&objid=1074330743&cfgid=1073741824&version=versionless&parent_id=1073984818&sequence=1


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## mark handler (Aug 23, 2011)

Where lateral support of studs (by means of straps, channels or similar steel members) is required in the design, the loads applied to steel studs should be based on the *steel-braced design. *The loads based on sheathing bracing should not be assumed, unless otherwise stated in the design.

http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?&name=BXUV.GuideInfo&ccnshorttitle=Fire+Resistance+Ratings+-+ANSI/UL+263&objid=1074327030&cfgid=1073741824&version=versionless&parent_id=1073984818&sequence=1


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## Codegeek (Aug 23, 2011)

Mark, I went through the UL directory and could not find anything about wood being permitted.  This rated wall in question serves as the wall along the water closet in an accessible stall, so we need to provide blocking for the grab bars.

Rkteck 1 - I offered up the use of Section 721 for calculated fire resistance rather than the components of the UL listing to allow for more leniency in the construction as far as permitted materials.


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## mark handler (Aug 23, 2011)

Metal Stud Backing







Wood not needed......


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## brudgers (Aug 23, 2011)

Codegeek said:
			
		

> Mark, I went through the UL directory and could not find anything about wood being permitted.  This rated wall in question serves as the wall along the water closet in an accessible stall, so we need to provide blocking for the grab bars.    Rkteck 1 - I offered up the use of Section 721 for calculated fire resistance rather than the components of the UL listing to allow for more leniency in the construction as far as permitted materials.


  You won't get there with calculated resistance and metal studs efficiently and there's no reason to use wood.


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## Coug Dad (Aug 23, 2011)

Could you use the exceptions in 603.1 (2006)?


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## Codegeek (Aug 23, 2011)

CD - I supposed you could use 603.1 exceptions except this isn't a Type I or II building.  I see your point though.  Like I said, I've had it drilled into my head that you cannot deviate from the UL listing, so I wondered what others thought as well.


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## brudgers (Aug 23, 2011)

Codegeek said:
			
		

> CD - I supposed you could use 603.1 exceptions except this isn't a Type I or II building.  I see your point though.  Like I said, I've had it drilled into my head that you cannot deviate from the UL listing, so I wondered what others thought as well.


   Given that wood studs have better performance in a one hour wall than steel - I personally would be more flexible were I a code official particularly given that similar walls can be constructed of metal and wood.   On the other hand, I might be less inclined to seal it - I'd have to think about it a bit more.


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## TJacobs (Aug 24, 2011)

I'm with brudgers...FRTW would be better IMO.


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## brudgers (Aug 24, 2011)

TJacobs said:
			
		

> I'm with brudgers...FRTW would be better IMO.


  Yep. One of the issues I deal with on this sort of thing is that down the road when there is an addition and the original building is being classified according to current code, the type of blocking is usually unknown.


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## pmarx (Aug 25, 2011)

mark handler said:
			
		

> Metal Stud Backing
> 
> 
> 
> ...


Bingo. Although we've never had an issue with any AHJ with wood blocking in a rated wall, this should remove all doubt. This or WingIt's.


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## Codegeek (Jul 25, 2012)

I'd like to expand on this subject and ask another question about UL fire rated assemblies.  If you have a one hour wall constructed to a UL listing, say U465.  Can you add materials on the outside of the wall?  Would one be able, say, to apply plywood with screws to the rated assembly?  Would the screws penetrating the rated wall affect the fire resistance of the wall?

I'm not finding anything in the UL Directory to indicate this cannot be done, but someone has asked me and I wanted to confirm my thoughts before I gave an opinion.


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## brudgers (Jul 25, 2012)

Does the UL listing include paint?


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## Codegeek (Jul 25, 2012)

brudgers said:
			
		

> Does the UL listing include paint?


No, which is why I don't see an issue with it, but the question was asked and I wanted to confirm.  Thanks.


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## kilitact (Jul 25, 2012)

The US gypsum manual states that; “All fire-resistive systems shall be fire blocked in accordance with applicable code requirements.” Section 717.2.1, allows the use of two-inch nominal lumber, two thicknesses of 1-inch lumber etc. Section 717.1 refers you to section 717.5 for types I and II construction. Section 717.5 refers you to section 603 for combustible materials in I or II type construction. This section allows the use of materials allowed by Section 717.5 which includes blocking.


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## cda (Jul 25, 2012)

Good question

On a door I think the answer is no

But a wall seems like the answer would most if the time be yes

If you have a rated floor assembly, you find carpet on top of it

The answer should be yes most of the time, till you get some bizarre set up someone wants to do!!!!!


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## Builder Bob (Jul 25, 2012)

cda said:
			
		

> Good question On a door I think the answer is no
> 
> But a wall seems like the answer would most if the time be yes
> 
> ...


Fire rated floor assemblies are tested for fire exposure from the bottom ,,,,,, (Just for informational purposes only)


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## kilitact (Jul 25, 2012)

Builder Bob said:
			
		

> Fire rated floor assemblies are tested for fire exposure from the bottom ,,,,,, (Just for informational purposes only)


Depends on the assembly


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## cda (Jul 25, 2012)

Builder Bob said:
			
		

> Fire rated floor assemblies are tested for fire exposure from the bottom ,,,,,, (Just for informational purposes only)


I was thinking of that but on a different line, the walls are blasted with the flame!!

have seen the other tests,but have never seen a floor test


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## Builder Bob (Jul 26, 2012)

I am sure that some assmeblies are tersted for fire exposure from both sides (same as vertical wall assemblies - some are tested for exposure from one direction only.)

On floor assemblies , I have never seen a floor assembly rated for fire exposure from the top side only.........


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## lunatick (Aug 7, 2012)

UL isn't the only game in town.

Gyp Association has a publication with modifiers listed in the front end.

Wondering if UL doesn't also. Like if you do this, than add that kind of language.


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## mtlogcabin (Aug 7, 2012)

> Can you add materials on the outside of the wall?  Would one be able, say, to apply plywood with screws to the rated assembly?  Would the screws penetrating the rated wall affect the fire resistance of the wall?


Existing Mexican resturaunt had stainless installed on the wall in the kitchen behind the range. It was attached to the wall with stainless steel screws into the wood studs ( not code compliant under todays code). The large wok on the stove top allowed the flames to heat the stainless after about 2 weeks of that an employee cleaning the wall noticed the wall was still hot more than 90 minutes after the stove was no longer in use. The interior wood studs on the 2 hour wall had started to burn. The FD determined the heat was transferring the gypsum board by the screws and over time had charred the wood and eventually started to smolder. Quick action by the employee and the FD and the resturaunt was back in businees for dinner the next day


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## GCtony (Aug 9, 2012)

mtlogcabin, That's a good lesson right there. This I will store somewhere in my memory bank.

Ya all are killing me, You teach me one thing and it leads me to come up with 10 more questions! Like I tell my kids..."Not a day goes by that you don't learn something"

Someone mentioned sec. 717; is the wall cavity in a wall assembly considered a concealed space?

Reading the prior posts got me thinking of a condition I will be running into.  I have a 1-hour tenant seperation wall that we will need to have PVC pipe within the wall for a central vac system. The pipe will run above the ACT ceiling, penitrate the wall, turn down inside the wall and come out the wall near the floor.  I understand the pennitrations will require fire caulk but my question is; is PVC allowed to pennitrate the wall and permitted to be within the wall.  My thought is no, in case of a fire, the PVC could melt and leave a hole in the wall. However, I've seen similar conditions but it's for plumbing, CPVC water lines, vent and waste.  A little help on where this is found in the IBC would be helpful. I'm looking at 712 but I think I need to be looking elsewhere.


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## steveray (Aug 9, 2012)

Tony...just like a ul listed wall# design, there are penetration designs as well....they days of "we'll just fire caulk it" should be over....there needs to be enough intumescent material there to seal the hole when the pipe melts away....in many circumstances I think caulking can be used up to about 2" pipe if the amounts are correct....Anything larger than that might require a manufactured "collar" that affixes to the wall and will seal the opening it is designed for....


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## GCtony (Aug 9, 2012)

Another question a little OT but I don't think is worth it's own thread. It's regarding 1017, corridors

I have a 6000 sq ft tenant space in your typ. strip center.  A-3 use, type II construction, not sprinkled, architects calculations are showing 90 occupants.  Imagine a space with rooms on the right of the space and rooms on the left with a corridor running down the center with an exit at the front and rear of the corridor.  The distance between the two exists, length of the corridor is roughly 80 feet. Plan review is saying that the corridor will need to be rated per table 1018.1. It's black and white but I've never run into rated corridors within a small tenant space. I'm wondering if this corridor in this tenant is not technically a corridor and just a common path of travel. The architect did use the word "corridor" on the drawings.  This plan reviewer is looking at exactly what is on the drawing and wont be doing the "oh, it's a mistake but I know what they mean, let me give them a call"


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## GCtony (Aug 9, 2012)

steveray said:
			
		

> Tony...just like a ul listed wall# design, there are penetration designs as well....they days of "we'll just fire caulk it" should be over....there needs to be enough intumescent material there to seal the hole when the pipe melts away....in many circumstances I think caulking can be used up to about 2" pipe if the amounts are correct....Anything larger than that might require a manufactured "collar" that affixes to the wall and will seal the opening it is designed for....


Thanks steve, Fire caulk or sleave seals will cover the actual pennitrations but does PVC pipe inside the rated wall affect the performance of the assembly, just like installing the wood blocking mentioned above?  We've been installing PVC and wood blocking in rated walls forever. What I'm getting at; have we unknowingly been doing this wrong all these years and also being missed by our inspectors?


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## steveray (Aug 9, 2012)

I know this is not really correct but.......

603.1.2 Piping.

The use of combustible piping materials shall be permitted when installed in accordance with the limitations of the International Mechanical Code and the International Plumbing Code.

I don't think it is an issue other than vertical exit enclosures which shall not be used for anything but egress (in a nutshell) no using those walls as a chase and nothing in them that does not serve the stairwell.....


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## north star (Aug 9, 2012)

*+ = **>*

GCTony,

The use of piping [ pvc & others ] is an approved material to

be installed inside of rated wall assemblies......The sealing

of the penetrations IS paramount though!......We typically

require the intumescent fire caulking around pvc piping

that penetrates or passes thru rated assemblies.



*<** = +*


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