ABS flange replacement and rough-in

[john_lemon]

I am remodeling a master bathroom which has 3/4 inch subfloor and a toilet flange that was all bent out of shape. I cut a piece of subfloor out along the center of 2 joists about 23 " long and 16" wide. The old ABS flange was going directly into a 3" 90. The 90 was exactly even with the top of the joist. After the 90 there was a 3" Y that connected to the sink drain, and then the pipe goes through another joist and down the wall. So there was no room to raise the flange up. I replaced the 90, the Y, and associated fittings. I bought a flange with a metal adjustable ring on the top, that fits inside a 3" 90 collar (I think it was called 4x3 closet). So, now that I have glued everything back together and I have a 90 even with the top of the joist I am worried ( a little late for that ) about the depth of the flange. There will be 3/4" subfloor, 1/4 hardi backer for ceramic tile, and finally 1/4" tile. So I have 3 questions:
The first question is about the flange installation. Looking at the flange, there is the SS metal top mounting ring, and then a plastic "ridge" that looks even with the taper of the metal ring around its edges. When I mount this should I cut the hole in the subfloor, backer, and tile so that the flange rests on that first plastic ridge which will also mean the metal ring is even with the floor? Or should I make the diameter big enough such that only the blue SS ring touches the floor?

The next question is the depth. Assuming the metal ring should contact the floor, that leaves 2 1/2" to go through 1/4 +1/4 + 3/4 (1 1/4"). This means that the flange would be inside the 90 fitting by about 1 1/4 inches, instead of fully seated at 1 1/2 inches. Is this okay?

The last question is about the rough-in. Without thinking enough, I made the center of the flange where the old one was at 14" from the back drywall. Should I have made it 12" for a more modern size toilet? I can still move it by cutting in the one spot where I have enough room for a coupling.

thanks in advance for any help.

[jadnashua]

The bottom of the flange should sit flat on the top of the finished floor and be anchored to it. This will put the top of the flange about 3/16 to 1/4" above the surface of the floor. If you can move it so it is 12" from the finished wall, then you will have more choices (and probably less cost) for a toilet. Make sure you account for the finished wall, and not just the studwall. My unprofessional opinion.

[john_lemon]

okay, thanks for the feedback. That means the diameter of the hole will be about 5" and the flange will have 2 1/4 inches to go through the tile, the hardi board, and the 3/4" subfloor. This means the flange will fit inside the 90 with 1", leaving a 1/2" gap. My biggest question now- is that enough? If not, what could I do?

Just in general - I know the ideal situation would be for any fitting to be seated the full 1 1/2, but is there a minimum that anyone here would recommend as a solid glue joint?

[PlumberWannabeJr]

okay, thanks for the feedback. That means the diameter of the hole will be about 5" and the flange will have 2 1/4 inches to go through the tile, the hardi board, and the 3/4" subfloor. This means the flange will fit inside the 90 with 1", leaving a 1/2" gap. My biggest question now- is that enough? If not, what could I do?

Just in general - I know the ideal situation would be for any fitting to be seated the full 1 1/2, but is there a minimum that anyone here would recommend as a solid glue joint?

No problem, even though it's not perfect. Just do not apply much primer, just a very thin layer, or only apply cement.

[john_lemon]

thanks for the feedback. I thought that would be fine, but just needed some assurance. It's actually ABS which I've never used primer on (isn't primer just for PVC).

It ought to be fun cutting through the ceramic tile for the flange. I've tried carbide tungsten blades for my jigsaw, and a ceramic tile bit for a roto zip. This porcelain ceramic tile is EXTREMELY hard to cut through.

[sulconst2]

to cut the tile use a dewalt masonary blade for a circular saw ($20). dont have to be too neat. the toilet covers a lot.

[jadnashua]

a diamond blade on a 4-5" grinder works well. When I did mine, I cut the tile across the middle of the opening, then using the same wet saw, nibbled out the area. That extra grout line is usually covered by the toilet, and even if it isn't, it looks fine most of the time. Using a grinder wheel, you can score around the circle, then plunge cut like pie-shaped segments and break out the chunks. Once you have them out, you can clean up the edge with the grinder. Note, it is usually a good idea to notch the tile so you don't have to drill through it to mount the flange. A hard porcelain floor tile is a bear to cut without using diamond cutting tools.

[john_lemon]

Sorry for the delayed response, and thanks for the feedback. I am also laying porcelain tile on a shower floor (sloped mortar bed) and I have to cut the small 1" tiles (on a 12" flexible sheet). I have to cut out the drain circle (about 4 inches in diameter). How can I do this? Unlike the toilet, I don't have the latitude of making rough cuts. It will be plainly visible so it has to be a pretty good circle. I searched to the end of the Internet for diamond jigsaw blades! I found one site of a company in China selling them, but the website wasn't that good and it didn't elaborate on them. My diamond wetsaw blade is the only thing that can cut through them...but it can't make a circle cut. I guess I could try going very slowly with the diamond grinder wheel?

MAN IS THIS TILE HARD TO CUT!!

any more ideas?