Flex Duct Firewall Breach

[John F. Swygert, III]

Guys, I see this all the time and need some clarification. Furnace located in garage with flex duct supply and return going through the garage wall and ceiling. I know flex duct is combustable however it's approved for use as furnace ductwork. But it's my understanding that ducts from house to garage must be min. 26ga. metal. Is this a breach??? How would you write it up? Many Thanks in advance.

[Joe Funderburk, CMI]

I don't think I've ever seen it unless the furnace is in a separate room with a solid door. If it wasn't, I would definitely write it up.

Put up a photo.

[Matt Berman, CMI]

in michigan should be 26 gauge metal and have a fire damper in both supply and return

[Jeffrey R. Pope]

I see it often. . .

Flexible ducting is penetrating the garage firewall. Building standards require that all ducts in the garage and ducts penetrating the firewall be equipped with fire-dampers or constructed of a minimum of No. 26 gauge sheet steel or other approved material and shall have no openings in the garage. This condition compromises the garage firewall system and should be repaired by a qualified HVAC contractor for safety.

[Joe Funderburk, CMI]

I see Studor vents occasionally.

[David P. Valley]

I call out all breaches in garage walls and ceilings that divide the living area from the garage...

Flexible ducts, any type of openings in the firewall (even the seams that aren't compounded), cable and wiring openings, etc.

If the firewall is open (breached) in any way, it gets red flagged.

[John F. Swygert, III]

Outstanding response. Thanks so much to all. Thats what i thought but I am seeing this weekly in 500K homes. Will take and add photos next chance.