HVAC Ducts To Garage

[Greg Subick]

Just finished one of the McKissock CE courses and read in one of them that HVAC system cannot supply conditioned air to a garage due to the risk of fumes venting back into living quarters through these vents. (this was in the cross-connection course) I did not know this and have seen it done in a few homes over the ten years I have been at this. Does anyone know of a legit code stating that this is not allowed?

[Jim Luttrall]

IRC R309
Garages and Carports
R309.1 Opening protection. Openings from a private garage directly into a room used for sleeping purposes shall not be permitted. Other openings between the garage and residence shall be equipped with solid wood doors not less than 1 3/8 inches in thickness, solid or honeycomb core steel doors not less than 1 3/8 inches thick, or 20-minute fire-rated doors.
R309.1.1 Duct penetration. Ducts in the garage and ducts penetrating the walls or ceilings separating the dwelling from the garage shall be constructed of minimum no. 6 gage sheet steel or other approved material and shall have no openings into the garage.

This is copied from the 2003 IRC but I don't think it has changed in later editions. Underlining is mine.

[Greg Subick]

Thanks Jim, I will be calling these out in the future.