According to the IRC, how high must a gas water heater be elevated above the floor in a private garage?

The correct elevation for a gas water heater installed in a private garage is 18 inches above the floor. This requirement is based on the need to prevent ignition of flammable vapors that may accumulate near the ground in a garage environment. By elevating the water heater, the combustion air intake is placed higher, reducing the risk of igniting any gases that may be present, such as gasoline vapors. This safety measure aligns with the guidelines set forth in the International Residential Code (IRC) to ensure safe operation and reduce fire hazards in residential settings.

While other elevations may seem plausible, the IRC specifies that 18 inches is specifically designed to provide the necessary clearance for safety in residential garages.