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18 inch Rule- Knowing when to measure up.

Submitted by DonHester on Sun, 01/04/2015 - 11:23.

18 inch Rule- Knowing when to measure up. Wenatchee Home Inspector

Here is a little more fun for when it comes to home inspections and garages. One area that seems to get a little controversial is the part of what designates a source of ignition when it comes to garages.

I had a discussion with local AHJ’s ( Authority Having Jurisdiction or better known as a Building Official) about electric water heaters in garages and some of my local AHJ’s have decided that they do not think that they need to be elevated to achieve the 18 inch requirement.

In that discussion I informed them by State Law as a home inspector we are required to report them if they are not elevated. It was interesting because the AHJ stated they do not like to be in conflict with other state rules and found the information I provided interesting.

This brings me to another item. Receptacles in garages less than 18 inches off the floor.

Now there is nothing in the NEC that I found that requires any elevation of receptacles in garages. In the IRC (Residential Code) is where we start getting a hint (see the code definition below)

Per the 2012 IRC definitions section-

IGNITION SOURCE. A flame, spark or hot surface capable of igniting flammable vapors or fumes. Such sources include appliance burners, burner ignitions and electrical switching devices.

. . .

Well this seems to catch a water heater, electrical or gas in my reading of the definition. But then what about receptacles? Well it does not define them in the “Such Sources” part of the definition but you can easily infer them in “A flame, spark or hot surface capable of igniting flammable vapors or fumes”. Anyone who has plugged or unplugged electrical equipment into or from a receptacle has seen them spark from time to time. I think this does lend itself to be a potential ignition source.

Yeah Garage receptacles do need GFCI protection also.

Then we have State law that comes in for home inspectors that seals the deal.

From the Washington State Administrative Code for home inspectors

WAC 308-408C-180 Attached garages or carports.

Report- as a fire hazard the presence of any ignition source (gas and electric water heaters, electrical receptacles, electronic air cleaners, motors of installed appliances, etc.) that is within eighteen inches of the garage floor.

So as a home inspector we are required to report them per state law and there is no way for a misinterpretation here as it is well defined.

Here are a few codes that are involved in relation to the issue of ignition sources; UPC 507.13 Installation in Garages, 2012 IRC G2408.2 and 2.1, 2012 IMC 304.3 and 2012 IFGC 305.3 Elevation of ignition source.

UPC 507.13 Installation in Garages.

Appliances in garages and in adjacent spaces that open to the garage and are not part of the living space of a dwelling unit shall be installed so that burners and burner-ignition devices are located not less than 18 inches (457 mm) above the floor unless listed as flammable vapor ignition resistant. [NFPA 54:9.1.10.1]

IRC G2408.2 (IFGC 305.3) Elevation of ignition source.

Equipment and appliances having an ignition source shall be elevated such that the source of ignition is not less than 18 inches (457 mm) above the floor in hazardous locations and public garages, private garages, repair garages, motor fuel-dispensing facilities and parking garages.

For the purpose of this section, rooms or spaces that are not part of the living space of a dwelling unit and that communicate directly with a private garage through openings shall be considered to be part of the private garage.

Exception: Elevation of the ignition source is not required for appliances that are listed as flammable vapor ignition resistant.

G2408.2.1 (305.3.1) Installation in residential garages.

In residential garages where appliances are installed in a separate, enclosed space having access only from outside of the garage, such appliances shall be permitted to be installed at floor level, provided that the required combustion air is taken from the exterior of the garage.

2012 IMC 304.3 Elevation of ignition source.

Equipment and appliances having an ignition source and located in hazardous locations and public garages, private garages, repair garages, automotive motor fuel-dispensing facilities and parking garages shall be elevated such that the source of ignition is not less than 18 inches (457 mm) above the floor surface on which the equipment or appliance rests. For the purpose of this section, rooms or spaces that are not part of the living space of a dwelling unit and that communicate directly with a private garage through openings shall be considered to be part of the private garage.

Exception: Elevation of the ignition source is not required for appliances that are listed as flammable vapor ignition resistant.

“Knowledge has to be improved, challenged, and increased constantly, or it vanishes.”

Peter Drucker

NCW Home Inspections, LLC is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…

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18 inch Rule- Knowing when to measure up.