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Need advice on mating concrete to toilet flange and doorways when leveling a floor.

Posted: Sun Aug 11, 2019 6:51 pm
by bomb20
Hello all, I've been working on a new basement bathroom and have been doing the heavy labor for it such as digging the trenches and such to reduce costs. Had someone come out to put the rough in drains and figured i'd lay the concrete back out.

Before i go that far i was curious about the different types of toilet flanges out there and if anyone had any comments to share about them. The toilet drain is 3" and was left with a flange which fits over it. This got me thinking about the approach to take with the concrete and had me looking at those that fit in, which seem to be easier to replace if needed vs one thats mated directly to the concrete on the outside. From the ones i've seen that fit in though, they strike me as more constrictive. Not only that, but some of them have a rubber gasket that gets rotated in some fashion to grab a seal and seems like something to fight with.

The outside fitting flange looks like it would provide better flow, but i would need to construct a close barrier around the toilet drain for concrete such as you would do with a shower pan drain.

If you suggest i go this far (cause i could be overestimating the massive craps a person can take and how the fit-in flanges would work), how would you suggest i leave a narrow gap around the drain such that i still leave ample concrete to secure the flange? I saw a mention somewhere to wrap the drain in some non-adhesive foam lining that can be scrapped out afterwards?

Besides that, I'll have to deal with the floor being somewhat out of level. What does one do when the low point of a room points toward the door? After all is said and done, there would be a bit of a lip that would need to be dealt with during the flooring process. I haven't dug that deep into things yet, but are there transition strips or tricks to deal with this? Mind you, the rest of the basement would be carpeted, and the spot that seems to be the most off is the bathroom area of course.

I appreciate any help, ty.

Re: Need advice on mating concrete to toilet flange and doorways when leveling a floor.

Posted: Sun Aug 11, 2019 7:01 pm
by bomb20
To add to this, the crew who came out cut the toilet drain a smidge below current concrete line. As i understand it i would want to install the flange on top of the flooring. Should i put and extension on the drain for safe measure or is there a small margin of error for how much drain needs to mate with the flange?

Re: Need advice on mating concrete to toilet flange and doorways when leveling a floor.

Posted: Sun Aug 11, 2019 9:26 pm
by Shannon
There are a few variations of flanges I have seen and they are a little different as far as the height of the pipe compared to the finished floor. In most cases you will be fine with the pipe sticking at least 3/4 of the way into the flange. You will need to add a piece of pipe on top temporarily so its above the floor height. Tape it on with duct tape and then wrap it with something to help create the gap needed for the flange to slip over pipe. Many flanges have an extra bulge right below the rim that may require some extra room near the surface of the floor also. Generally a couple layers of cardboard wrapped around is good. Wrap that with some tape and pour away, simply use a screw driver to pick out the cardboard after the concrete is cured.