Hot Water Heater Question

Hey everybody I inspected a gas water heater on a new construction yestarday. The heater is in a dedicated enclosure connected to the house. The water heater sits on the ground but should be on a pedestal. The builder is arguing that because it is not in the house or garage that it does not need to be 18 inches off the ground. My take is that it is still a gas water heater and should be 18 inches off the ground. The enclosure is connected to the master bath which is connected to the master bedroom if the water heater explodes so does the master bath and bedroom. So am I correct in saying it should be up off the floor. Also they didn’t connect the TPR discharge pipe.

Check the manufacturer’s installation spec for the particular model.


As Joe suggested, check the manuf specs, but generally speaking, it is not required to be raised unless it’s in the garage.

This may help. I could not upload the whole file because it was too big.

Y’all got me worried there. My old water heater sits straight on the floor in the basement.

But I’m probably still not code compliant. I do not have a dedicated drain for the TPR valve or a drain pan. But there’s nothing to damage down there.

And it does look like an example of another silly rule. 18 inches above ground or not, in a garage if a car hits it, it’s gonna make a mess.

The 18 inch rule isnt really for fear of cars hitting it. The reason it is 18 inches off the ground is because gases can collect low on the floor and create a combustion hazard with the burner of the hot water heater then boom there goes the garage.

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That should apply to unfinished basements as well then. I have paint, a mower and a small amount of gasoline in mine (kept well away from the furnace and water heater). I know I should move the gasoline.

You know i have seen water heaters sitting on slab etc…But the truth be told you loose energy as well as the bottom of the water heater will deteriorate faster on a electric water heater sitting on floor.Should sit on catch pan (recommend in my reports).Gas should be elavated due to flamable fumes always fall to the lower 4 to 6 inches from the floor.(hair spray,air freshner etc…Flammable products!

Plumbing codes (…at the least the IPC/IRC…California uses the UPC) do not require water heaters to be raised 18 inches unless they are located in a garage or a room accessed from a garage.

The reason is that gasoline vapors are denser than air and hover near ground level.

Keeping the ignition source at least 18" above the floor reduces the chances of igniting gasoline fumes.

The 18" requirement applies to electric water heaters as well.

There is no such requirement to raise a water heater above floor level in any other part of a house.

I inspected a home with the hot water heater sitting directly on the dirt outside with no protection from the elements except a roof and closet around it (and not much of one at that). What do you guys say about exterior ground. I know they don’t have to worry about vapors etc… but I’d think that the unit would have the potential to be damaged well before it’s lifetime on exterior ground.

Yes, Gas water heater can not be installed on the floor/ground. Gas water heaters on the ground are possible to explode due to the pilot flame being so close to the floor. Due to the risk of fuel being spilled from anything code requires it off the ground. Specs may say they can be on the floor/ground but code will not allow this


I have heard of some gas water heater with sealed combustion chamber thus eliminating that requirement…

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Water heaters should not be placed directly on the “dirt,” but they can (absolutely) be installed at floor level with no danger of “exploding.”

When installed in a garage, unless they are a FVIR type, they must be raised to at least 18 inches off the floor to prevent the potential of igniting fumes or vapors that may be present in the garage. In some jurisdictions, even the FVIR type are required to be elevated in the garage.

Nice try on your first post in 4 yrs, but completely inaccurate. Manufacturer specs IS the code in most jurisdictions.

How do these old threads get dug up?