I need to design a partition wall in an existing type 1a building with a fire rated roof. The partitions need to be braced to the underside of the metal decking of the ceiling/roof assembly. Is it ok to penetrate the existing assembly with screws?
Page 64 shows screw size and spacing for the rated assemblies, but it's for the face screws; I don't think there's a rule when you are attaching a partition if said partition will also be rated.
agreed...the tested assembly involves the required fastening. So, unless you're violating the assembly by removing required fasteners (or other materials), you should be good adding fasteners to that structure
I don't think additional fasteners violate the fire rating of the existing protected roof, unless they are wood pegs (or other weird thing) or somehow create voids/interruptions in the rated roof assembly
Typically that is correct. It all depends on the rated assembly and the number / size of the fasteners though. I know of several 2 hour assemblies that have requirements for penetrations of any type (including fasteners) that need to be sealed with fire caulk.
We always include typical details for these situations. Usually for a non-rated assembly head detail at a rated assembly, we specify a slotted top track without issue about fastener spacing. It's not like it's adding new loads from underneath that could reduce the performance of the steel deck. Head details at rated gypsum membrane ceilings are another thing and far more complicated.
JLC, not sure how it’s down south, but membrane is what we refer to when detailing fire separations made of gypsum sheets. At least that’s how my code calls them.
Fire caulking is only required on rare occurrences for certain types of assemblies. Hence why you need to find an assembly similar to the existing ceiling. Realistically you won't need to worry about the fasteners penetrating the membrane of the rated assembly.
It’s a typical steal frame metal deck system. I’m thinking ul902
Dec 21, 23 3:21 pm ·
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proto
my guess is the steel deck itself is not adding much value to the fireproofiness of your existing condition, whether what's above it is exterior gyp or concrete. So, if you penetrate low flutes, you aren't penetrating a "membrane"...[purely speculative from this side of the internet...ymmv
]
A couple of things. Look at the existing building codes. Second, you can scrape of fire proofing, as long as they patch it back, I'm presuming it's cementitious. Firestopping.
Dec 21, 23 7:04 pm ·
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Screwing to a fire rated roof/ceiling assembly
What about bracing to a fireproofed beam?
Thank you
What dose the UL listing for the existing assembly say is allowed?
I'd probably ask your AHJ what they think will be allowed. You'll need that in writing when your special inspection is done.
You bet! Good luck with this. I know it's a pain to deal with.
These are the reasons why i still like going to archinect. Genuinely interesting but very non-sexy question. Thx! (Also more of this type of stuff)
Page 64 shows screw size and spacing for the rated assemblies, but it's for the face screws; I don't think there's a rule when you are attaching a partition if said partition will also be rated.
https://www.usg.com/content/da...
agreed...the tested assembly involves the required fastening. So, unless you're violating the assembly by removing required fasteners (or other materials), you should be good adding fasteners to that structure
I don't think additional fasteners violate the fire rating of the existing protected roof, unless they are wood pegs (or other weird thing) or somehow create voids/interruptions in the rated roof assembly
Typically that is correct. It all depends on the rated assembly and the number / size of the fasteners though. I know of several 2 hour assemblies that have requirements for penetrations of any type (including fasteners) that need to be sealed with fire caulk.
We always include typical details for these situations. Usually for a non-rated assembly head detail at a rated assembly, we specify a slotted top track without issue about fastener spacing. It's not like it's adding new loads from underneath that could reduce the performance of the steel deck. Head details at rated gypsum membrane ceilings are another thing and far more complicated.
are there other devices screwed to u/s of existing deck such as lights and carrying channels? How are those fasteners treated?
what membrane?
The fire protection membrane
JLC, not sure how it’s down south, but membrane is what we refer to when detailing fire separations made of gypsum sheets. At least that’s how my code calls them.
this is what membrane means "down south" - https://www.merriam-webster.com/dictionary/membrane
and this is how the 2021 IFC confuse the terms and doesn't really define what a membrane is
"fire caulk" is primarily for smoke sealing. Side note, seach the forum for the classic "show me your caulk" discussion.
Fire caulking is only required on rare occurrences for certain types of assemblies. Hence why you need to find an assembly similar to the existing ceiling. Realistically you won't need to worry about the fasteners penetrating the membrane of the rated assembly.
my guess is the steel deck itself is not adding much value to the fireproofiness of your existing condition, whether what's above it is exterior gyp or concrete. So, if you penetrate low flutes, you aren't penetrating a "membrane"...[purely speculative from this side of the internet...ymmv ]
this one? yeah, fire away!
A couple of things. Look at the existing building codes. Second, you can scrape of fire proofing, as long as they patch it back, I'm presuming it's cementitious. Firestopping.
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