Kelly
From Wiki2
Kelly
HVAC and the garage
Want Bad Air? Put a Heating & Cooling System in Your Attached Garage
"According to the HVAC building code :
IRC 309.1.1: Ducts in the garage and ducts penetrating the walls and ceilings separating the dwelling from the garage shall be constructed of a minimum No. 26 gauge steel sheet or other approved material, and shall have no openings in the garage."