TOPIC: Ductwork okay to be in Garage?

I have seen a few homes that have ductwork from the main house extended into the garage. I usually warn the client about this, though I don't really mark it as a safety defect in the report. I have seen articles on the internet and other places about "how to properly extend the trunk and ducting to the garage". It just doesn't seem safe to me. It seems that fumes or a garage fire would have direct piping to the rest of the house unless the furnace/ac is actually operating, "pressurizing" the ducting. Is it a defect to have ducting in the garage like this? I can't find any codes against it, but it just appears to be hazardous to me.  ???

If there is a return or supply register open into the garage I call it out as this can allow off gases to enter the distribution system and be distributed through out the liveable areas. Also a breech in the firewall.

Now if just ducts with no openings can be OK if sealed and insulated properly. Should be in warm zone (conditioned) and not just in an unheated garage (unconditioned). Usually a liveable area over an unheated garage with exposed pipes and ducts can be a major issue.

Thanks, David. That is my thinking-open duct registers to the garage to heat the garage can carry fumes or smoke from a fire to the interior of the home. This particular case has unfinished but insulated ceilings in the garage, and I didn't see a return. The homeowner was there, and of course, argued the system was installed by a legit HVAC Contractor and should be safe. I'm not going to argue with the homeowner whether the contractor is legitimate or not, but I still see it as unsafe and improper to put registers in the garage unless it is a separate system not attached to the rest of the living quarters.

Must be 26 ga hard piped duct.

No registers allowed in a garage.

okay, great David! That's what I needed to know, and it's good to hear from someone in the business. I do find it odd that I see it so often, and it makes perfect sense why it shouldn't be there! I usually suggest a separate heating system for the garage if they want it heated. Some homeowners ask me if they can simply block off the registers(if there's no return). I always suggest a qualified HVAC Contractor. I doubt blocking the registers is going to stop fumes or firewall breach