Closet flange: Cast Iron vs ABS

[Jbrk]

I'm in the middle of a bathroom replacement.

I will have a 3" cast iron arm for the water closet drain. (It was lead, I took it out, replacing with a cast iron arm for sound purposes)

So here I am doing my parts list and need to pick a new closet flange. Trying to find cast iron closet flanges at the plumbing supply is kind of difficult, and it made me wonder why.

Trying to find info like this on the internet for something this specialized and nuanced is rather difficult. So I came back the TL forums.


So far the pros/cons if have found are:

Cast iron:
It's secure, it won't deflect or move or crack when the toilet sees forces applied to it. But it can rust out over time (50 years?)


Abs:
It's cheap, it's easy, it'll never rust. But It's weak, it can deflect or crack over time.



Anyone have any thoughts or experience?


Thanks,


Jamie

 

[Reach4]

What vertical thing will be coming up?

I would consider a cast iron compression closet flange, but you need the riser to be the right size. https://www.jonesstephens.com/no-caulk-flanges

When you say ABS, are you thinking inside compression, or what?

No experience.

 

[Sponsor]

 

[Jbrk]

What vertical thing will be coming up?

I could either have the 3" CI pipe come up through the floor, and I'll cut it flush after. (So the compression fitting would work with this)

Or since I have access under the floor, I could cut it below and use an MJ coupling.

When you say ABS, are you thinking inside compression, or what?

Ya, these are seemingly the easiest to find from suppliers, the compression version or just a straight connection with an MJ coupling to the pipe. All the supply houses carry the ABS ones in stock and I don't have to special order it (like I have to with most cast iron flanges).

 

[Reach4]

I had to search for MJ coupling: https://pexhouse.com/product/4-mj-or-no-hub-coupling/

If you are using a shielded connector, you could use a spigot ABS or PVC closet flange. These can be had with a stainless steel ring, and that is very preferable. A 3 inch spigot closet flange has the same dimensions as a 3 inch schedule 40 plastic pipe.

 

[Jeff H Young]

Ill add if using a spigot closet ring use a shielded coupling such as mission band cp33 for 3 inch cast iron to 3 inch plastic is one option . a standard 3 inch no hubcoupling is improper for joining plastic to cast iron

 

[Jbrk]

Very good. Thank you for mentioning that.

But back to the question: Are cast iron closet flanges better than plastic?

Is there a difference at all?

 

[Jeff H Young]

cast iron is better than plastic in my opinion . Id use plastic with stainless steel attached ring easier and should be good for 50 plus years . if sound is a extremly bug issue run cast iron the whole way . but I think we are nit picking.