smoke dampers located in conjunction with barometric dampers

[BayPointArchitect]

Given:

Fully sprinkled, eleven story building

2009 IBC

2000 NFPA

Eleven story stair shaft with stair pressurization system that will keep smoke out while allowing doors to open. Supply fan is mounted on top of roof with a duct penetrating the top of the stairs.

12" x 12" barometric dampers are located near each and every door to ensure the that pressure is exactly 1/16" water column (12.5 pascals).

The problem is that if these openings within the 2 hour rated stair shaft were equipped with smoke dampers circuited to the alarm system, then the dampers would close and the stair pressure would exceed that which is allowed. Therefore it may become too difficult to open the doors (more than 30 pounds of pressure) thereby creating an impedance to safety.

Reference:

2009 IBC Section 716.5.3 Exception #4.

Air transfer opening within shaft enclosure does not require smoke damper where ducts are used as part of an approved mechanical smoke control system designed in accordance with Section 909 and where the smoke damper will interfere with the operation of the smoke control system.

Question:

May these vents remain without protection where located between the stairs and corridor?

Thanks

ICC Certified Plan Review

 

[cda]

Did you look at 716.2.1

Looks like an alternative is needed ??

Not a damper person but since it is a rated wall do you need fire dampers??

 

[Dr. J]

No. Big red flag.

All ventilation equipment must be independent from the building and must be either external to the building, or be in a separate 2 hour enclosure to the building. It goes all that is holy about vertical exit enclosures to punch them with holes and then rely on a mechanical device.

See IBC 909.20.6.1 and 1022.5

 

[Dr. J]

UH, goes AGAINST all that is holy ...