Is a Gas Water Heater allowed to have a plastic overflow pan?
This is a code change item in the 2018 IRC 2801.6 and YES it can. A plastic pan shall not be installed beneath a gas-fired water heater beneath a gas-fired water heater shall be constructed of material having a flame spread index of 25 or less and a smoke-develope index of 450 or less when tested in accordance with ASTM E84 or UL723.
Good info!..thanks, Paul.
How do we check this? I cannot find one sold for a gas WH. Some will say something like “NOT FOR GAS”, but that cannot always be seen once installed.
504.7 Required Pan
Where a storage tank-type water heater or a hot water storage tank is installed in a location where water leakage from the tank will cause damage, the tank shall be installed in a pan constructed of one of the following:
A plastic pan shall not be installed beneath a gas-fired water heater.
Taken right from here;
I used Kansas Code because it does not have ammendments.
Yes, IPC still doesn’t allow it. It’s in IRC.
A plastic pan beneath a gas fired water heater shall be constructed of material having a flame spread index of 25 or less and a smoke develop index at 450 or less when tested in accordance with ASTM E84 or UL 723.
As with anything else that has an ASTM or UL rating there should be a stamp or sticker on the fixture.
That is correct no plastic pans shall be installed under a gas fired water heater
Another case where the IPC don’t jive with the IRC.
A flaw for sure Marcel.
The pan will have to be label for use with gas fired water heater. No label=no go.
Yeap, makes the life that much easier 
Have you seen one in person? I hope they are smart enough to put that on the rim in multiple spots where it could be seen once installed.
The kicker is the next code;
P2801.6.1 Pan size and drain. The pan shall be not less
than 1 1/2 inches (38 mm) deep and shall be of sufficient
size and shape to receive dripping or condensate from the
tank or water heater. The pan shall be drained by an indirect
waste pipe of not less than 3/4 inch (19 mm) diameter.
Piping for safety pan drains shall be of those materials
indicated in Table P2906.5. Where a pan drain was not
previously installed, a pan drain shall not be required for a
replacement water heater installation.
The last line makes the whole thing ridiculous. My gas water heater installed last year has a plastic pan underneath with a capped drain. First year my water heater ever had a pan and there is no floor drain in my laundry room (sump is at the other end of the house). Do I need a pan / NO do I get a pan? YES Will it help anything? NO!
Thank you Paul - Just updated my reports
Much easier around here they usually don’t install a pan. 
The other thing I see quite often is a washing machine on a wood floor with no pan and drain.
I love the conversations and how everyone researches topics. Please keep sharing and encourage others to participate. That’s how we learn and grow in this industry. Remember there should be no stupid questions or negative comments that can cause others to not participate. Please be encouraging and supportive to everyone.
Great support, Pau! 
