Bathroom wet vent/flat vent and toilet venting

[EOProps]

We are in the middle of a bathroom renovation and wanted to check in on whether the existing plumbing is installed correctly. We've uncovered some interesting things and bad shortcuts that were done over the years in this house and aren't sure if the current bathroom plumbing needs to be added to the list!

There is a laundry closet on the other side of the bathroom. This plumbing looks OK and has an individual dry vent. The shower waste line connects with the waste line of the WM and is wet vented by the drain of the sink. Sink is dry vented, connecting with dry vent of WM, and connects to main vent stack. To us, this all seems to be OK.

The area in question is the toilet waste line connection and venting. The toilet connects to the waste line before the waste line from the WM, shower, and sink. The main vent stack is after the waste line for the WM, shower, sink branch, which connects to the waste line via a turn through a 45 ell and a 45 wye, with the 45 wye on its side, but with appropriate slope into the main waste line. The toilet waste passes this 45 wye connection before hitting the main vent stack. So, it seems that in essence, the toilet is first vented by the connection to the WM, shower, sink branch before hitting the main stack dry vent.

Is this set up OK? It seems that this would cause the toilet to be wet vented on the WM, shower, sink branch. It seems it also creates a bit of a horizontal vent, since the 45 wye is on its side, sloping upward to a 45 ell that connects that sloped drain pipe from that WM, shower, sink branch. If the connection is 45 degrees or more, does it just count as a wet vent. If not, I know flat vent rules vary by state. The house is in Maryland (Baltimore). It seems that they have adopted the IPC without changes to wet vent guidance.

I've tried to attach a rough drawing of the setup, though I don't know if my lack of drawing ability and perspective will confuse things further! The blue lines are vents. There are cleanouts (one on WM dry vent above santee and one at the end of the line on the 45 wye that connects the toilet closet bend. The WM, shower, sink branch is 2" pipe, both for vents and drain pipes.

 

[Terry]

The washing machine can wet vent anything. It's a pumped drain.
Wet venting is done with bathroom fixtures, a lav, a tub, a shower and a toilet downstream of all of that.
A washing machine would come in downstream of those fixtures, or in other parlance, each would have their own vent before entering the main drain.

 

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[EOProps]

Thanks for your response, Terry. Am I correct in interpreting that you meant to say that a WM cannot wet vent anything? I'm thinking that was what you intended to say in the first line.

Pardon my ignorance, but I thought that since the WM had a dry vent, it wasn't being wet vented? Is it just the case that it currently drains into the same line as the shower and sink, that would make it both dry and wet vented and that would be a problem? Right now, the shower and the toilet are the only fixtures without a dry vent. The shower wet vents off the sink drain. The toilet may wet vent off the WM, shower, sink branch (this is part of what I'm confused by), and also dry vents on the downstream vent stack. I've attached a new drawing that might better depict the current set up. Dotted lines are dry vents, with the thicker one being the main vent stack.

If this is incorrect, it seems that the WM needs to run independently of the drain for the shower and lav, even though it is also dry vented, and would enter the main drain after the shower, lav, and toilet. Is that right?

 

[Terry]

The shower needs a vent "before" it enters the main line and so does the toilet.
The washer prevents you from doing any wet vents there.

 

[EOProps]

Got it - thanks, Terry. Of course, this leads to one more follow-up question.

This doesn't come through in the drawing, but the space is tiny. The entire house in only 11 feet wide. The house is also from the 1800s and wasn't originally built with an indoor bathroom. I can see how the current location of the bathroom was the most logical, but it does present some difficulties in getting this all up to snuff. There is the space to run the WM on its own line with dry vent before entering the main, so that can be fixed up. We can leave the shower and sink on the same branch, with the shower wet venting off of the sink and leading to a dry vent that connects to the main vent stack. The issue would now be getting the toilet it's own vent before hitting the main line. The toilet is currently installed with its back against a brick wall. The flange is only about 1.5-2 ft away from the main line and only about 3 ft away from the main vent stack. Without reconfiguring the entire bathroom, there is no room to move the toilet without violating code in terms of its distance from other fixtures. Given its proximity to the main stack (3 ft), is it possible to rely on that stack to vent the toilet, even though it is off the main line? I doubt this makes a difference, but there is yet another 3" vent stack further downstream prior to the main cleanout, which is about 8-9 feet downstream of the main vent stack. Thanks again for your feedback, it has been extremely helpful.