# Return  Air  Plenums



## north star (Jul 29, 2020)

*: = : = : = :*

I have an existing Fire Rated corridor with the spaces above
it being used as a return air plenum...….The spaces in this
particular area of an existing bldg. are sprinkled.

*Q:*  If there are thru penetrations in the fire rated wall assembly
above the corridor [  i.e. - ducting, conduit, piping, air openings,
etc.  ], are the penetrations required to be sealed with an
approved fire caulking or by using fire rated dampers that match
the rating of the corridor, or does the presence of sprinklers
below the ceiling negate the requirement ?

I am looking for the Code sections that require the thru
penetrations to be sealed, or that allow the openings to not be
sealed.

The applicable Codes are the `18 I-Codes...….The NFPA Standards
could also be applicable, ...not sure a this point.

Thanks for your input !

*: = : = : = :*


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## cda (Jul 29, 2020)

Just to clarify

Are any of these penetrating a rated assembly???

Or are they outside the envelope


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## steveray (Jul 29, 2020)

Is the corridor ceiling rated?


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## north star (Jul 29, 2020)

*$ $ = $ $*

I am still gathering information on all of the variables involved
with this application, so I am not sure about the actual fire rating
of the existing wall assemblies & the ceiling assembly in the
corridor.

Will post here when I have some more definite info.

Thank you !

*= = $ = =*


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## Rick18071 (Jul 29, 2020)

see 714.3 of the 2015 IBC


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## north star (Jul 29, 2020)

*# ~ #*

FWIW, more info regarding my initial posting...

The RDP is saying that the corridor [ in question ]
is not a fire rated assembly, but does have numerous
thru penetrations in it...…..The plans are not that
clear.

We are going to schedule a meeting with the RDP's
to clarify.

Thank you all for your input !

*# ~ #*


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## jar546 (Jul 29, 2020)

Return air plenums are overrated.  Who needs them anyway?


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## cda (Jul 29, 2020)

Sprinkled building

May equal non rated corridors allowed, so any penetrations do not matter


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