There are two additional installation requirements beyond the standard ones when a gas water heater is installed in a garage, and both are intended for minimize the possibility of starting a fire in the garage by either igniting fumes from a gasoline leak onto the floor or rupturing the gas line to the water heater from being hit by a car.

1. Because gasoline fumes are heavier than air and will collect near floor level when there is a puddle of leaked gasoline on the floor, the water heater must be elevated a minimum of 18-inches off the floor, UNLESS the water heater is Flammable Vapor Ignition Resistant (FVIR) rated, which will be noted on the data plate at the side of the water heater. All water heaters manufactured after July 1, 2003, are required to be FVIR compliant. This means the flame inside the base of the water heater is in a sealed compartment and will not ignite any fumes around it. See our blog post What is an FVIR water heater? to learn more.
2. The code also requires that gas appliances located in a garage, such as a water heater, “shall not be installed in a location subject to vehicle damage except where proved by approved barriers.” Typical approved barriers are a bollard or wheelstop (parking bumper). This safety measure is not necessary if the water heater is not located in front of the path of a car in the garage. 

    Another blog post to check out is What are the most common installation mistakes with water heater replacement?.

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Here’s links to a collection of more blog posts about WATER HEATERS:

• Are water heaters required to be raised off the floor? 

• Can a Temperature and Pressure Relief (TPR or T&P) valve be mounted to discharge horizontally?

• Where are gas water heaters not allowed to be installed?  

• Is the minimum size water heater inlet pipe 1/2" or 3/4" according to the building code? 

• Can you use a light switch for a water heater disconnect? 

• How can I tell if a water heater is HUD-approved for mobile/manufactured homes?

• Can you wire a 240-volt water heater with 120 volts? 

• Is it alright to have a shut-off valve on both the hot and cold water pipes at a water heater?  

• What is the minimum clearance to doors and windows for an outdoor tankless gas water heater? 

• What is required clearance for access and working space in front of an electric water heater? 

• Why is the water heater older than the house? 

• Does a water heater need a shut-off valve? 

• Why should a tankless water heater have an isolator/service valve kit installed?

• When was a gas water heater first required to be elevated 18 inches above a garage floor?  

• Can the temperature and pressure relief (TPR) valve discharge pipe for a mobile/manufactured home water heater terminate under the home? 

• What is the purpose of a thermostatic mixing valve above a water heater? 

• Does a tankless gas water heater still work with no electricity during a power outage?  

•  Why do water heaters have a sacrificial anode? 

• What is the difference between a manufactured/mobile home water heater and a regular water heater? 

• Does a tankless water heater require a pressure relief valve?

• When is a water heater drain pan required?

• Why is there water in my water heater drain pan?

• What does it mean when a water heater Temperature/Pressure Relief (TPR) discharge pipe is "trapped"? 

• Can I leave a gas water heater in place when remodeling a garage into a family room or bedroom? 

• Where do I find the water heater in a mobile home?

• Does a tankless water heater in an attic require a drain pan? 

• Does an electric water heater require a disconnect? 

• Is a catch pan and drain piping required for a replacement water heater?

• What is the difference between a single element and dual element electric water heater? 

• What is an FVIR water heater?

• What is a heat pump water heater?

• What is a dielectric union?

• What's that powdery crust on the pipe connections at the water heater? 

• What are the most common installation mistakes with water heater replacement?

• Why is my water heater making strange (rumbling, gurgling, knocking or banging) noises? 

• What can I do to make my water heater last longer?

• How can I determine the age of a water heater if the serial number is missing or decoding it is impossible? 

• How does a hydronic heating system work?

• What is the difference between a regular water heater and a direct vent water heater? 

• What is the difference between a regular water heater and a power vent water heater?

• What is backdrafting at a gas water heater? 

• How do I determine if a water heater is gas or electric?

• What does it mean when a gas appliance (water heater, furnace, or range) has been "red tagged"?  

• What's the valve with the flip-up handle on the water heater for?

• Why is an older water heater an insurance problem?

   Also, visit our WATER HEATERS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

Illustration by Code Check.