Interpretation #7089
Published October 24, 2012
Original Request
- Code Version
- 2010
- Code
- MECHANIC
- Code Description
- Mechanical
- Chapter
- 6
- Section
- 603.7
- Topic
- fire damper in metal duct
Question
Is it the intent of the mechanical code not to require a fire damper in a metal duct penetrating a wall separating a garage from a dwelling unit and what are the exceptions.
Answer Published 10/24/2012 at 10:26 AM
No fire damper is required in the duct
penetration from the garage to a
dwelling unit unless the building code
requires such wall to maintain a
specific fire resistance rating.
penetration from the garage to a
dwelling unit unless the building code
requires such wall to maintain a
specific fire resistance rating.
Commentary
This section of code assumes
an unrated wall assembly between the
dwelling unit and garage. The section
intends to create a fire resistant
barrier between the garage and dwelling
unit without creating a specific rated
assembly. As such, flexible duct may
not be used to penetrate such walls.
Some AHJs have allowed the use of 1-
inch (minimum) fiberglass ductboard as
an alternate to the minimum 26 ga.
metal duct(see FBC-R section 302.5.2).
However, this is a decision the local
Building Official would have to make.
BOAF has no position on the approval as
an Alternate Method or Material based
on the section quoted in this request.