Are vents required in garages? Especially if there is a gas fired water heater or furnace? Lately I’ve been inspecting some newer construction (2003 or newer) and there are no vents installed.
In rare cases a vent will be required. It all depends on the manuf requirements that are based on type of equipment, total btu’s and size of the garage. Some water heaters that vent out a side wall have a section of the same duct that also provides intake air.
The garage itself does not necessarily require venting. I’d have to look up the reference, but I believe the CMC states that venting is not required when the garage is less than 1000 sq ft and is used for “storage” of 5 or less vehicles.
“Additional” venting is required when the size of the garage (cu ft) will not adequately support combustion for all of the gas-fired appliances located within.