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fire stop the ductwork chases at the deck above?

syarn

Silver Member
Joined
Jan 20, 2010
Messages
251
Location
Philadelphia, Pennsylvania, United States
IBC 2009; schaumburg, Illinois. renovation (change of use) to 1800 sf ground floor tenant space from mercantile to assembly A-2 (restaurant) in large mall (the streets of woodfield). existing 2 story building height. the existing building is 1B Non-Combustible w/ an Automatic Fire Sprinkler System.

new work includes connecting new bathrm exhaust fans to existing vertical exhaust, 3 new exhaust fan ducts, new supply duct for new RTU, 3" vent for plumbing, multiple elec conduit & 3 refrigeration line sets. see links for sketch & photos.

the new ducts, vent pipe, conduit & line set are to be run up thru the existing 2nd floor inside an existing shaft and than penetrated horizontally above the finished 2nd floor ceiling below the roof deck over to the rooftop locations. also 2 ducts from neighbor tenant penetrate the new work space above finished ceiling and than go vertical up in this same shaft enclosure. there are 2 openings in 2nd floor - one is 60" x 60" and the other is 32" x 60" BOTH inside a 6' x 6' existing shaft enclosure.

https://docs.google.com/open?id=0B8MIb4l-3dteSE9GbzB2eHZTbGFTNEZ1N2thcFlsZw

https://plus.google.com/photos/114799267650135397288/albums/5727224131148109233

the building inspector is requiring the ductwork chases at the 2nd floor deck above to be fire stopped.

should the rating on this fire stop be 2 hours because of table 601?

the existing shaft wall construction from 2nd floor to roof deck looks to be 1 hour U415 system A....

can the "fire stop" be achieved by just installing rated fire dampers and a rated through-penetration fire stop system between the ducts, line sets, vent pipe & the existing 2nd floor rough opening edges?

OR do fire dampers have to be installed "within the shaft enclosure" so a NEW horizontal assembly has to be constructed BELOW the location of the NEW dampers and the existing 2nd floor (sort of like a drop down rated GWB enclosure that "boxes around" all duct work, etc. & returns back to the existing 2nd floor beyond the openings?

UL does not seem to have any approved designs for "multiple" ducts through-penetration firestop systems under C-AJ-8000 or 7000 series...any suggestions?
 
pardon me...not sure how to edit my initial post;

correction; there is 1 existing 6' x 6' shaft fed by 1 existing 60" x 60" opening with 3 existing ducts running up thru it....

it is proposed to add a new 6' x 6' shaft fed by a new 32" x 60" opening with 4 new ducts, line sets, etc.
 
I believe any fire-stops or fire damperss would need to be 90-minute rated assemblies.
 
716.3.2.1 Fire damper ratings.

Fire dampers shall have the minimum fire protection rating specified in Table 716.3.2.1 for the type of penetration.

TABLE 716.3.2.1

FIRE DAMPER RATING

TYPE OF

PENETRATION MINIMUM DAMPER RATING (hours)

Less than 3-hour fire-resistance-rated assemblies 1.5

3-hour or greater fire-resistance-rated assemblies 3
 
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