How big to cut hole for toilet flange

[mjm]

This seems like it would be a pretty easy question to find the answer to... but I am coming up blank. Wondering how big of a hole to cut for toilet flange.
I put new subfloor and plywood underlay in a bathroom remodel.
I am now putting in a new abs flange. so looking at the flange it has a bevel (not sure if that's the right description?) on the bottom that is 1/4" rounded.
so, if I cut the hole exactly 4" to fit the body of the flange, it would sit 1/4" higher off the floor than if I cut the hole 4 1/2" to accommodate this bevel.
After this bevel is another 1/4" of flat (part of the actual drain piece) and then another 1/8" difference to the actual flat part that should be on the floor that the bolts and screws attach to.
hope this makes sense.
I am confused as it looks like I have 3 options, 4", 41/2 " or 5".
here's a pic of where the red lines show where the floor level could be

 

[Breplum]

Do yourself a HUGE favor and get a flange with a stainless steel ring. They are not expensive and won't break readily as ALL plastic flanges do eventually. Trust me on this.

 

[Sponsor]

 

[Reach4]

If using that flange, I would say 5.25 diameter if the red line ring is lower than the outside of the flange. But if you are going to glue a flange in, I suggest you follow greplum's advice.

Depending on what is below, you might be able to use a nice compression flange, such as Code Blue. Making a clearance hole for that is a little more complex, but if you ever redo the floor, that compression flange can be removed. Gotta get glue right the first time.

It was wise of you

 

[mjm]

Those metal flanges are not popular around here, Canada. I have never seen any in any big box Reno stores either, maybe a smaller plumbing store might carry them, not sure.

a compression flange is intriguing, like a waxless ring. Are they trustworthy?

 

[Reach4]

Trustworthy.

What are you connecting to? vertical 3 inch ABS pipe, or hub down how far?

 

[mjm]

vertical ABS.
don't know if it matters but, I have access from below, I know this because I actually chipped the existing ABS pipe out of the 90.
I have that connection to worry about next.

 

[Reach4]

Yes. 3 inch pipe vs 4 inch pipe matters. The length of the pipe matters.
Looks like the Jones Stephens C40320, which can go outside of a 3 inch pipe is incredibly expensive in Canada. A 3-inch pushtite ( Sioux Chief Part#: 888-GPM or 888-GAM ) has a plastic ring. But if it were to break or you redid the flooring some day, it can be removed because it is not glued.

If 4 inch, then there are more choices.

 

[mjm]

3". The flange I have now in the pic is a 4x3.
I do see at HD there is a Oatey 3" twist - n - set. maybe I'll try that.
why would they sell that brass cover with it?

 

[Reach4]

Bad pairing by their computer. That brass is for something else.

 

[mjm]

That's what I thought, made no sense to me, but also a good chance I could be wrong.
Anyways, I guess I am going to cut the hole big enough to fit the flange in so it will fit on the flooring, which will just be vinyl floating, so not much, I am also going to probably get that push in flange too, along with a waxless gasket, and see how well the technology works. sounds way less messier.
thanks for the feedback

 

[Reach4]

With floating flooring, you normally don't want to pin the flooring down. But IMO, the toilet will pin the flooring. So I am thinking that you just make sure that the gap around the edge is distributed equitably before pinning the floor into place. My thinking is that the farther an edge is from the toilet, the more gap that might be needed for thermal expansion. I don't know that professional flooring documents address this. To have a toilet not pin down the flooring would require a gap and molding all around the toilet, and we don't want that IMO.

 

[mjm]

Actually in another bathroom I did, I cut out a circle of the flooring and pinned it under the flange and then the actual flooring ran up to that with about an inch gap. Made sense to me back then, I may do the same again, but I have yet to dig into the cabinet on top of the flooring or not argument. In that bathroom I put in cabinet first and then ran the flooring up to it.
I was searching for the push in or not flange debate thread, but can't find it yet.

 

[Reach4]

I was searching for the push in or not flange debate thread, but can't find it yet.

But the toilet gets held down. That would pin the flooring by the toilet base pressing down.

May I suggest some searches for you?
toilet flange twist
toilet flange compression

pushtite