# Fire Resistance V497



## vegeta82 (Nov 29, 2021)

This design was submitted for consideration.  At first glance I presumed it was protection from 1 side.  But after review it indicates several places the design protects for fire from both sides.  This seems contrary to other designs I have seen and my experience.  Have others seen this design?  Does it in fact protect from fire form both sides.

 U497 Link

See page 11.

I appreciate any input.


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## vegeta82 (Nov 30, 2021)

Brief edit.  See page 21 from the second link.


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## ChrisCampbell (Dec 1, 2021)

I agree, you don't see too many rated wall assemblies with gyspum on only one sides of the studs, but yes, this does appear to have achieved a rating from both sides.


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## vegeta82 (Dec 1, 2021)

ChrisCampbell said:


> I agree, you don't see too many rated wall assemblies with gyspum on only one sides of the studs, but yes, this does appear to have achieved a rating from both sides.


Appreciate the input Chris!  

I have not see really any such systems for walls.  Some Floor/Ceilings and Roof Ceilings with some one sided type assemblies but this is a first for walls.

Curious if others have worked with this design or similar.  Because if its compliant why bother with all the fancy shaft wall and track systems and why bother submitting designs with protections on both sides if one side is sufficient.


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## ChrisCampbell (Dec 2, 2021)

vegeta82 said:


> Appreciate the input Chris!
> 
> I have not see really any such systems for walls.  Some Floor/Ceilings and Roof Ceilings with some one sided type assemblies but this is a first for walls.
> 
> Curious if others have worked with this design or similar.  Because if its compliant why bother with all the fancy shaft wall and track systems and why bother submitting designs with protections on both sides if one side is sufficient.


My guess would be that the 3 or 4 layers of gyp on one side of the studs doesn't work for many applications.

For shaft wall assemblies, the shaft liner is often spanning multiple floors (but not always). For V497, I believe the gypsum would have to be sitting on the floor on each level - don't see anyway that the laminating compound applied between layers could support the weight of the boards themselves, meaning the boards have to rest on the floor.

Many designers may also just not like having exposed studs on one side of the wall.

Definitely an interesting option though!


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## instantmessenger (Dec 2, 2021)

ChrisCampbell said:


> I agree, you don't see too many rated wall assemblies with gyspum on only one sides of the studs, but yes, this does appear to have achieved a rating from both sides.


This type of assembly is a typical common shaft wall assembly. It's used in every highrise (and lowrise) building. Yes, the rating is on both sides.


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## Paul Sweet (Dec 3, 2021)

I wonder if the studs have to be a heavier gauge so they don't melt before the hour is up.  I don't see how it could pass the hose test without the studs.


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## vegeta82 (Dec 6, 2021)

Paul Sweet said:


> I wonder if the studs have to be a heavier gauge so they don't melt before the hour is up.  I don't see how it could pass the hose test without the studs.


Paul, I assume the gauge of the stud is critical to the test.  But there is also a 2hour variation of this and the studs do not change with the added rating so this also confuses me a bit.  It is almost like the studs and screws are designed for a 2 hour rating and the membranes and connections won't fail even with the fire on the stud side.  Again this is odd to me.


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## IJHumberson (Dec 8, 2021)

Weird arrangement having exposed steel studs on one side, but UL assemblies will note "Exposure Side" and "Non-exposure Side" when the assembly is rated for exposure from one side, so this one appears to be rated from both sides.


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## vegeta82 (Dec 9, 2021)

IJHumberson said:


> Weird arrangement having exposed steel studs on one side, but UL assemblies will note "Exposure Side" and "Non-exposure Side" when the assembly is rated for exposure from one side, so this one appears to be rated from both sides.


Appreciate your feed back and I concur.


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