Flooring, Ditra and Toilet Flanges

[JanSolo]

Hello again wise plumbing masters; I have a couple of questions for you about my bathroom remodel.

My bathroom looks like this currently:

My plan is to put down some 3/4 plywood over the angled floorboards, put Ditra (+heat) over that and then tile.

Tile
Ditra (+heat)
3/4Ply
Floorboards

This should work ok, yes?

My question is regarding the toilet flange; I have some 4inch abs pipe sticking up thru the floor; I'm ok to attach the flange over the finished tile once I'm done.
When I screw the flange to the subfloor, it's going THRU the tile and thru the Ditra; doesn't that compromise the waterproofing? Won't water just flow down there and mess up my subfloor?

In fact, how do I make sure that water cannot just flow down the side of the ABS Pipe that the flange is attached to? I mean, if kids spill a lot of water on the floor, won't it go under the toilet and down that space?
I've searched a bit and I've not seen a real answer for how to waterproof the inside AND outside of the toilet flange hole.

Edit: I'm not sure I explained it very well, so I made a picture to illustrate what I mean. How do I avoid this?

As always, I appreciate all your help, wise plumbing elders!

Cheers

Jan

 

[Jadnashua]

In a typical bathroom, you don't expect a bunch of water on the floor of the room. But, yes, I supposed if things leaked enough, it would get into the system.

BUt, if you install your toilets properly, the wax seal shouldn't ever leak. Now, if the toilet were damaged, yes, it could leak, and there'd be little to prevent water from getting onto and therefore into the floor. Hopefully, you'd notice before things got bad enough to cause long term damage.

If you notch the tile for the flange anchors prior to setting it, it makes things a bit easier as you then, don't have to try to drill holes through your tile. The proper position of the flange is on top of the finished floor, and anchored through it into the subflooring. You need to abide by the clearance rules about distance from fixed object when routing the wire around the toilet.

You could use some KerdiFIx, or silicone caulk around the riser to the flange to seal it to the floor if you wanted, as long as it didn't mess with the cementing of the flange to the pipe.

 

[Sponsor]

 

[Terry H]

We are required to caulk under toilets here. The inspectors go around with their inspection papers and run them under the toilets, if they can fit their paper it’s a no go.

silicone is tough so I use this white caulk that dries clear. I leave a small gap in the back of the toilet so that if the toilet does ever leak it will seep out and you can catch it before it messes up your floor. I think caulking will solve your problems here and is code for some places. Plus it just helps the toilet in the long run remain stable.

 

[JanSolo]

In a typical bathroom, you don't expect a bunch of water on the floor of the room.

You guys havn't met my kids!
The whole reason I'm doing this remodel is because they splash so much water out of the bath that it went down and messed up my basement ceiling.
I'm replacing my old water-radiators with Ditra-Heat because the radiator pipes went thru the floor, letting water in.

I'm gonna Kerdi the shit outta my walls & seal it to the Ditra floor to make it as waterproof as possible. I'm considering adding a Schluter floor drain; maybe a door kerb too.

 

[Jadnashua]

If you rely on just tightening the bolts to hold a toilet in place over a tiled floor, expect it will move. SO, the caulk around the toilet is both for stability and for sanitary reasons. If you were worried about water from a leak getting into the floor or the Ditra, then you might want to caulk around the flange to the tile as well. Note, that the tile isn't waterproof, but hopefully, if there was a leak, you'd notice before it became a major issue. You'd run into the same thing around the perimeter of the room and out the door into the hall, and that normally isn't waterproofed, either.

A floor drain gets messier, and trying to seal the drain to your waterproofing layer gets a little messier. You might want to consider a Kerdi drain. Floor drains are somewhat of a pain, as you then have to consider a trap primer, as they don't often get enough water into them to keep the trap seal intact otherwise.

Hopefully, the children will outgrow that problem.

 

[wwhitney]

Without regard to whether the level of water proofing you are looking for is required, even if you could seal the flange to the tile, you'd have another leakage path. Namely, water migrates through grout and thinset, so it can get into the Ditra and then to the hole in the Ditra.

If you really want to avoid that (say you're building a wet room bath, where the whole room is the shower), I would think you'd need to set the toilet on, say, a solid surface base whose top surface is maybe 1" above the top of the tile. That goes in before the Ditra, and after Ditra you can Kerdi to it with an upturned flange of Kerdi like at the walls. You might need some sort of perimeter tile taller than the field to hide the upturned Kerdi.

Cheers, Wayne

 

[Jadnashua]

Often a bathroom will have a baseboard, and that should cover that area. Schluter does make some nice cove profiles that can make cleaning that joint easier in both metal and plastic. Depending on the tub skirt, that can present a challenge to waterproof, and there, caulk may be useful.