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Garage and house heating with same forced air furnace

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I purchased a home that has the garage converted to living space. I plan to convert it back to a garage, but would like to keep it heated. Do I need to install a smoke/fire damper in the HVAC supply line feeding the garage? Ducts are in the attic and the furnace is in a mechanical room at the center of the house. Attic is currently not separated between house and garage, but I will do so when I convert.
asked in Car Garage by harold (120 points)
edited by darekrudy
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1 Answer

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Hi Harold,
You cannot use the same forced air heating system for a house and garage heating purposes. I’ve explained that already in Attached Garage Firewall  posts (item #4)
The following are 2006 IRC (International Residential Code) paragraphs that refer to your questions:
  • 309.1.1 – Ducts through a garage wall or ceiling common to a house must have minimum 26-gauge thick steel walls
  • 309.1.1 – No air duct openings in the garage from the same heating system that is used for the house heating purposes
  • 309.1.2 Air duct penetrations of garage – house common wall drywall surface must be sealed with approved firestop caulking (this is new in 2006 IRC)
Let me know if you have any other questions, just click “comment” below.
answered by darekrudy (21,730 points)