BOAF Interpretations

Interpretation #5619

Original Request

Date: March 23, 2008
Requested By: wayne bauman
Requester E-Mail: wbauman@aeieng.com
Code Version: 2004
Code: BUILDING
Code Description: Building
Chapter: 7
Section: 716.5.4.1
Topic: Fire/smoke damper requirements
Question: Is it the intent of section 716.5.4.1 to provide smoke dampers at all penetrations of corridors required to have smoke and draft control doors regardless of whether openings serving corridor are served from a separate branch and protected with a fire/smoke damper. Comment: A duct main penetrates and is routed within a 1 hr. rated corridor required to have smoke and draft control doors. Duct main has multiple branches which serve rooms located along corridor. Each branch penetration is protected with a fire damper. Prior to duct main entering boundaries of corridor, a separate, dedicated duct branch connected to main, is routed into corridor to serve corridor diffusers. If a fire/smoke damper is installed at corridor penetration of dedicated duct serving corridor, and duct is constructed of minumum required thickness, do smoke dampers need to be installed at each of the other main duct branch penetrations serving the rooms? Seems overkill to install smoke dampers at all penetrations, not to mention very costly. Would not smoke damper at branch serving corridor protect openings in corridor and meet intent of code?

Answer on 03/23/2008 at 8:39 PM

As described, IF there is only one branch duct penetrating
the corridor wall which is feeding/open to the corridor,
and IF the other ducts (without openings in the corridor)
are constructed of steel not less than 0.019-inch (0.48
mm) in thickness, then this is the only duct not meeting
the exception to the requirement for the smoke damper. The
one smoke damper in the branch serving the corridor would
effectively isolate and prevent the corridor from
communicating with the adjacent spaces and the intent of
the code would be satisfied, provided the corridor is NOT
an exit passageway.

Commentary:

This exception is prescriptive, it must be applied as written. See, FMC, 607.5.4 Corridors/smoke barriers, Exception #3. Smoke dampers are not required in corridor penetrations where the duct is constructed of steel not less than 0.019 inch in thickness and there are no openings serving the corridor and the corridor in question is not considered an exit passageway. Exit passageways and exit enclosures are required to have an independent ventilation system. This is also covered in the Mechanical Code section 401.4 - Exits. This also assumes the doors within the corridor meet the requirements of 715.3.3.

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