# Ceiling Finish / Fire Issues?



## eyan50495 (Jun 1, 2020)

Hi All

This is for a NYS Commercial Space (M):
-1 Story + Basement
-11,000 SF Floor Plate
-Type V-B (*Fully Sprinklered*)
-Roof Construction: Steel Posts, Microlam Girders with TJI Joists + Advantech Roof Sheathing
-1st Floor Construction: 3-1/2" Concrete on Metal Deck over Microlam Girders w/ TJI Joists + Steel Posts

I have two questions that the contractor can't seem to answer either. 

On the ceiling assembly of the 1st floor, we wanted to put large wood panels up (3/4" maple plywood). In my reading of IBC, this would be fine as the ceiling requirements only need to have a Class C flame spread. In NFPA 13, 9.2, It says that by putting the wood up against the TJI joists we are creating a large cavity and that we'd have to attach the wood panels over resilient channels with 3-1/2" non-combustible insulation above it. In addition, each volume within the TJI / Ceiling Cavity would have to be limited to 160 SF? We believe this is the only way to avoid having sprinklers above the ceiling and below.

Am I reading this correctly? Might it be easier to just put Gyp. Bd. over the ceiling and then attach this wood ply (which could go down to 1/2") over it to avoid this assembly?


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## eyan50495 (Jun 1, 2020)




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## steveray (Jun 1, 2020)

Fill the space with insulation.....Depending on how deep your TJI's are, it will be the only way to get under 160....The channel shouldn't be required..What edition of NFPA 13?


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## eyan50495 (Jun 1, 2020)

steveray said:


> Fill the space with insulation.....Depending on how deep your TJI's are, it will be the only way to get under 160....The channel shouldn't be required..What edition of NFPA 13?


Hi Steveray, 2019 NFPA 13. The TJIs are 24" deep and at times 12" OC. 

Yes, section 9.2.1.6 says 'concealed spaces formed by ceilings attached to composite wood joist construction either directly OR onto metal channels not exceeding 1" in depth, provided the joist channels as measured from the top of the batt insulation are separated into volumes each not exceeding 160 ft2 using materials equivalent to the web construction and at least 3-1/2" of batt insulation is installed at the bottom of the joist channels when the ceiling is attached utilizing metal channels, shall not require sprinkler protection.'

How are they measuring the 160 SF? Is it the void created from the top of the insulation to the decking above? Would you put fireblocking between the joists to limit the volumes?

Thanks for the reply!


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## cda (Jun 1, 2020)

eyan50495 said:


>




You need to make pictures a link and post the link

Or to easy post, become a Sawhorse, and you can direct post pictures and stuff, and support the forum!!


Best advice, talk to the fire sprinkler designer, there are various ways to design a sprinkler system, and for concealed spaces.


Eyan, have I asked what you do for a living?


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## ADAguy (Jun 1, 2020)

This is a good one, can you provide a section/plan of the area in question?


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## cda (Jun 1, 2020)

Call the Guy

Sprinkler Guy


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## steveray (Jun 1, 2020)

Measured from the top of the drywall...The insulation is AND (additional requirement) after the fireblocking...Sounds like you will be firecaulking every penetration through every joist. Or fill the cavity....Newest 13 I have is 2013....

Nice Jeep!


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## eyan50495 (Jun 3, 2020)

Spoke with some local FA/FP subs - it seems we will have to put gyp. bd. tight to the joists or we'd have to put a fire alarm in each bay (at least here in Nassau County). We may have to fill the top with insulation so we don't have to have sprinkler heads above and below as well. 

It would also seem that regardless of a wood paneling or ACT, we have to put Gyp. Bd. tight to the joists or again, sprinkler + fire alarm above the ceiling.


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## cda (Jun 3, 2020)

eyan50495 said:


> Spoke with some local FA/FP subs - it seems we will have to put gyp. bd. tight to the joists or we'd have to put a fire alarm in each bay (at least here in Nassau County). We may have to fill the top with insulation so we don't have to have sprinkler heads above and below as well.
> 
> It would also seem that regardless of a wood paneling or ACT, we have to put Gyp. Bd. tight to the joists or again, sprinkler + fire alarm above the ceiling.




Anyway do a simple drawing of the layers, pre anything, and post the drawing in a link, or if you can direct upload it. 

With dimensions.

Any FPE friends? that might look at it?


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