Is Drywall on One Side of Fire Barrier Acceptable?

12/29/2023

I’m wondering if you can help me on this one.

I have a project with the detail below referencing the use of the U419 listed assembly, but with the drywall only on one side of the assembly.

I asked for verification that the U419 assembly would permit this and he provided me with the attachment referencing section 5A. I don’t believe that was the intent for section 5A of the listing, but I can’t figure out what the actual intent is.

Is drywall on only one side of the assembly here correct?

Is it allowed anywhere?

It is something that has come up since there is a V497 listed assembly that puts both layers of drywall on one side of the wall, but my understanding has always been that it was used only on the interior side of exterior walls required only to be rated from the inside (IBC Section 705.5).

Any assistance would be greatly appreciated. I appreciate your help.

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11 Comments

Glenn Berger

12/29/2023 08:32:32 am

The detail shown is not the UL design. Any deviation to an UL design requires an EJL to be signed a qualified official of a firestopping company and approved by the AHJ(s).

Can drywall on one side of a wall assembly be an acceptable design for an one-hour fire barrier? Potentially, depending on the wall design.

sean

12/31/2023 06:41:35 pm

I would not accept a fire stopping company to do the designing of alternate fire rated assemblies.
I don't accept fire stopping contractors from doing alt. designs for fire stopping.

SEBAS

5/17/2024 12:46:49 pm

Unless you're the fire marshal, if a certified fire engineer says it's equivalent to the rating you are trying to achieve - tough luck. Have fun trying to hold up someone's project on opinion

Raul Bull

6/10/2024 03:42:03 pm

V497

Mike Meyers link

12/29/2023 08:41:58 am

Normally see this construction in strip malls. It provides some fire protection while adjoining spaces are under construction. Then wall is finished on opposite side as retailers move in.

Jesse

12/29/2023 08:45:42 am

That's definitely not the UL design. And yeah, walls like that are common pre- tenant finish-out, but not after. Fire does funny things to metal studs

Chris Miiler

12/29/2023 01:49:50 pm

This is done with specific AHJ approval as an alternate means due to infeasibility in existing construction situations. It is defintely not a UL. Most recent case has sheetrock on the other side but none of the joints were sealed. The sealed two layers were on the public side protecting the tenants within.

12/31/2023 06:39:24 pm

This does not qualify. They need to do something else. Modifications to a listing requires retesting or more work than that is needed.
Follow chapter 7 of the IBC.

1/2/2024 10:47:55 am

This National Gypsum article reads to me that UL Design V497 would work as an interior wall with a fire hazard on either side of the wall, but with gypsum on only one side of the wall:

https://www.nationalgypsum.com/who-we-are/blog/fire-resistance/build-fire-rated-asymmetric-wall-assemblies-one-side

Gary Erickdon link

1/3/2024 10:52:52 am

Someone has to say fire tested assemblies only.
There are shaft wall and membrane tested rated assemblies available in UL.
Alternative solutions are granted on a single site as needed basis. Prove there isnt an acceptable solution. Construction schedule snd cost relief aren’t AS parameters.
As for mall partitions base building supplies base complete fire separations including fire-stopping, not tenants. Tenants should not be starting construction without base building occupancy.
FAFO.

Aaron Millar

1/3/2024 11:48:56 am

In UL design U419, 5A appears to only modify the outer layer on one side of the assembly. It is not replacing the entire assembly listed in 5, it just changes one layer out of everything used in item 5.

"(As an alternate to Item 5) — 5/8 in. thick, 24 to 54 in. wide, applied horizontally as the outer layer to one side of the assembly."

Similarly 5B and 5E only modifies the base layer, etc. These don't replace the whole build-up of the wallboard.

Use a shaftwall or similar system if your wall can only be assembled from one side.

Is Drywall on One Side of Fire Barrier Acceptable?

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