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Tile installation around toilet drain pipe

4 years ago

I'm installing cement board and tile on top of sub-floor in a new bathroom. All the cement board and tile installation videos say to cut a 7" hole in the cement board/tile to fit it around the toilet flange. However, all the toilet install videos say the flange should sit *on top* of the tile. Which is it?

The hole in the subfloor left by the plumber is 5.5" in diameter even though the pipe is only 4". I matched the cement board hole size to the subfloor hole. The 7" flange will technically still cover the hole, but the screw holes will be right at the edge which seems like it will crack the tile/cement board. How is this normally done?

Featured Answer

PRO

Mint tile Minneapolis

4 years ago

last modified: 4 years ago

There is no guarantees here, the smart thing to do is correct it now rather than POSSIBLY later. The flange needs full support and all screws into solid wood underlayment. Or your taking a gamblers risk. Thats after meeting deflection and proper buildup for a tile assembly.

As is you may expect toilet bolt issues and possibly cracking tiles or both., maybe next month maybe in years.

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Comments (10)

kudzu9
4 years ago
A picture of what you're dealing with will help. Despite your detailed post, I'm not quite visualizing everything.
catbuilder
4 years ago
Ideally the flange should sit on top of the finished floor, although you can deal with it if it doesn't. What is your subfloor? Is it new construction, or a new bathroom in an older house? Why did the plumber make such a big hole? Do you have access to it from underneath to repair it? It's possible that your current subfloor is inadequate, in which case you will need another layer of plywood anyway. If that's the case, you will of course make the hole the correct diameter and problem is solved.
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Thanks everyone for all the great input and suggestions. My reading is that the kitchen pipe is likely able to be rerouted into the wall, but the bathroom may be trickier due to the presence of the 4x4 and the shear wall. @weedmeister Thanks for clarifying that tripled counts as doubled. @ksc36 I had somehow missed that the code allows for an exception if a stud shoe is used. Good to have as a backup option. @joseph_corlett @Jake The Wonderdog Yes, the inspector has the final say. I've submitted these questions to the inspector but so have have been unable to get ahold of them. @User No 2nd floor or snow here. The bathroom wall is a shear wall for earthquake resistance (not wind), so that wall may post the most challenges. @ci_lantro Great point about the ID / OD. I'll have to double-check the measurements on-site to confirm whether this will even be possible without using a stud shoe. I will be meeting with my contractor later today and will ask about drilling through the floor. I do have a crawl space below so maybe that can be a solution. @cat_ky Thanks for the vote of confidence in cutting the cabinet. I wanted to clarify that my concern is not just about the back of the sink cabinet, but rather that I'll be making a 2" H x 2" D notch into edge between the back and the side panels, substantially weakening the supported weight. In particular, the cut into the adjacent cabinet (trash for kitchen or drawer for bathroom) will go almost 40% of the way across the back. I'm planning for a farmhouse sink + stone countertop, so there will be quite some weight. I've attached a diagram in case that helps visualize the cut. Do you still think this is not a problem? @Jeff Grenz Thanks for the context. I've reached out to my structural engineer for comment. The weird part is that I can't seem to find where on the plans they indicated the installation of a 4x4 post at that location in the bathroom wall.
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margaret17
Original Author
4 years ago
New bathroom in older house in a converted garage. New plywood subfloor was put in about 10" above the concrete slab to make room for plumbing. I have no access from underneath since it's such a small space. Now that I think about it, it was probably the carpenter who put in such a big hole since the plumbing had to go in before the new subfloor went down. Although the plumber was there after and didn't say anything about it. I'll take a picture today and add to post.
margaret17
Original Author
4 years ago

Here's the photo.
margaret17
Original Author
4 years ago
I'm wondering if I should tile in closer to the pipe over the gap, but I'm worried the tile would crack if not supported by anything underneath. Or just tile up to edge of cement board.
PRO
Creative Tile Eastern CT
4 years ago
"The hole in the subfloor left by the plumber is 5.5" The flange will set on top of the tile. End everything at the opening left by tradesman. If in doubt call your contractor for the definite response. You Tube and open forums are a dangerous place to gather technical information.
PRO
Green Hammer Construction Consulting
4 years ago
I agree with Creative Tile Eastern CT. This is probably not the place to be getting your final answer to your question. There is not requirement in (at least Michigan’s) code for where the flange is supposed to be mounted other than clearance from the wall and cabinets. I know for jobs we have done in the past the flange is actually mounted to the subfloor by the plumber. Make sure to ask your plumber for where they want it installed. They are the ones responsible for the connection to the stool should there be an issue down the road.
margaret17
Original Author
4 years ago
Unfortunately I *am* the contractor, which is why I was asking here. Was trying to see if someone who does plumbing could let me know if the hole was workable.
margaret17
Original Author
4 years ago
The flange covers the hole, but one (of four) screw holes is going into nothing, and two are are within half an inch of the edge of the cement board. The last one is fine.

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