4" PVC for toilet drain - help

Hi Folks! I'm new to this forum.
The issue: the bathroom (basement one) has been roughed in by the previous owners and the toilet pipe is a white 4" pvc. I was able to find a black ABS toilet flange to fit nicely inside the pvc, but now I've read that I cannot glue the two unlike materials together properly (although there may be some special glue??). Need advice on what to do - I cannot source a PVC flange anywhere here in Ontario so far (tried Lowe's, Home Depot, HomeHardware - all have only ABS).

Here is a visual of what I'm working with (see attached). The shower drain is existing and so is the toilet. I'm adding the Lavatory line that joins into the shower drain after the trap.
Does the Lav need to be vented or is it wet-vented with the existing 2" abs that vents everything else? I could also run a line straight up from the lav area in the wall and connect to the 2" abs vent which runs horizontal above.

The lav is not vented and therefore the shower is not vented either.
The toilet is not vented with the right fittings.

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I'm not sure what they use primarily for dwv in the east, but here in the west it's pretty much all ABS. If you need something fancy in PVC, you are going to have to try your luck at a plumbing wholesaler. There is glue for mating the two types of materials, it's called transition cement, but you are better off finding a true PVC flange if you can get it.

After looking at your second post's diagram, it's clear that you have alot of work to do there, everything is plumbed wrong. Your shower and lav are both wet vented incorrectly and your toilet will suck their traps dry. You need to vent each fixture separately (best), or at least vent the lav sink. I am not sure why PVC was used at all since you have ABS everywhere else.

It is rather interesting that in some areas of the country, ABS is the standard, in others is all PVC, and then in some places, both are available everywhere. I don't know why that is, either actually works well. The transition cement is not recommended by most participants on this forum. ABS and PVC are made of different chemicals, and when we "glue" fittings to pipes, we actually solvent weld them. This requires a different solvent for each type so the only way most folks recommend to transition is with a no-hub connector. Would it be possible to get rid of the PVC and go with all ABS? I trust you will get the venting problems resolved because what you have won't pass inspection and won't work properly.

Steve89GTA said:

- I cannot source a PVC flange anywhere here in Ontario so far (tried Lowe's, Home Depot, HomeHardware - all have only ABS).

Click to expand...

You looked in all the wrong places for a pvc flange. Not a standard fitting in Ontario

To start with, transition cements are allowed in Ontario underground as long as its only for 1 joint to make your transition.

If you want to source a pvc floor flange, you will find the gray pvc in Ontario. You can check Desco, or Nuroc in the GTA. Both are plumbing suppliers. They are both in the book/net

Many thanks folks! I was able to confirm by the local inspector that the transition glue is ok. I was considering a fernco adaptor to change the 4" pvc to abs below grade but that would not pass.

If I vent the lav/shower combo via a 1 1/5 abs connected directly to the 2" vent up top, would this satisfy the venting requirements? I'm told that the existing toilet/shower drain setup vented through the 2" abs had already passed insp. I'm only adding the lav on the other end.

see revised graphic which includes 1 1/2 abs vent.

If I vent the lav/shower combo via a 1 1/5 abs connected directly to the 2" vent up top, would this satisfy the venting requirements? I'm told that the existing toilet/shower drain setup vented through the 2" abs had already passed insp. I'm only adding the lav on the other end. See graphic above

From the vanity connection in the wall, if you go up at least to 42" above the floor (technically, it's 6" above the flood rim, but a lot of inspectors like 42"), you can then cross over and connect to the vent line anywhere it is convenient (in the attic?).

Thank you! This is all I needed, and just in the nick of time. Yes, the connection to the 2" vent will be at 8' from the basement floor. It then goes across and up and connects in the attic of the house to the pipe extending through the roof.

floor rim

It is NOT "technically 6" above the flood rim". It is '42" OR 6" above the flood rim, whichever is HIGHER'. That is to take care of the situation if a 36" kitchen sink were to be connected to it at some later date. But, if a higher sink, such as 42" were installed THEN it would have to be 6"above the rim, not 42".