Stack Venting - Toilet and Shower

I've communicated with a master plumber on another forum, but wanted to check with you all on what he said.

I have a toilet that is 4' away from the main stack, and a shower that is 2' away. Is it possible to install a fitting like the one below to stack vent both the toilet and the shower?

fitting

That is how we do it, and it is what the fitting is made for. In fact, depending on how the fixtures are arranged, sometimes you can install it at the lavatory with a tee into the riser for the sink, and just have one vertical vent pipe for the entire bathroom.As long as there is not another toilet, or anything, above it.

Nope, that's all. Thanks for the info

I love that fitting

I have a vertical 4" stack that serves the entire 2nd floor which has a toilet, tub shower, vanity sink, kitchen sink, and a washing machine. This layout was all existing, and this 4" stack continues up thru the roof as the vent.

The 4" is all cast iron on the 2nd floor, and the other drain lines tied in are 1 1/2 copper.

The washer was added years later and the plumber cut the cast iron 4" vent section that went up thru a closet in the bathroom and ferncoed in a section of 4" pvc with a sanitary tee for the 2" trap for the washer.

The 2nd floor transition tee under the floor by the toilet is a 4" cast iron combo wye laying on its side, with cast iron 90s on both ends, one 90 goes up to the roof, and one down, and it drops thru wall in corner of the 1st floor bathroom, into the crawlspace, where it changes to PVC with a shielded fernco, makes a long sweep 90, then a 4" PVC wye ties the 1st floor toilet, tub shower, and vanity into the horizontal 4" drain section. It then 90s at foundation wall, goes outside has a 2 way clean-out tee, then at the curb another clean-out.

So the 4" stack is also serving as the only vent for the 1st floor bathroom, and also the entire 2nd floor.

I want to remove all the cast iron and copper and do it all in PVC since I am remodeling upstairs bathroom and kitchen and have the sub floor out since it was rotted under the tub.

It has never clogged in the original configuration, (we owned the house for over 40 yrs), so should I just do exactly what was there but in PVC, using the fitting shown in this post where toilet ties into the stack to replace that huge cast iron combo wye on its side setup?

The stack is a wet vent but is it ok to leave it as such, since the layout is existing?

I am in NJ we are using the NSPC 2009.

Thanks.

No residential code allows wet venting between floors.

I understand it currently does not meet the 2009 NSPC venting rules.

To correct it would require tearing out a lot of cabinets and walls on the 1st floor to run another separate vent line off the main 4" horizontal drain and bring it up to the 2nd floor.

I found this in the Admin section of the NSPC 2009

ADM 1.4 APPLICABILITY
1.4.1 Addition or Repair
Additions, alterations or repairs in compliance to this Code may be made to any existing plumbing system
without requiring the existing installation to comply with all the requirements of this Code. Additions, al-
terations or repairs shall not cause an existing system to become unsafe, insanitary or overloaded.
1.4.2 Existing Plumbing Installation
Plumbing systems that were lawfully installed prior to the adoption of this Code may continue their use,
maintenance or repairs, provided the maintenance or repair is in accordance with the original design, loca-
tion, and no hazard has been created to life, health or property by such plumbing system.
1.4.3 Existing Use
The lawful use of any plumbing installation, appliances, 
xtures, 
ttings and appurtenances may have their
use continued, provided no hazards to life, health or property have been created by their continued use.
1.4.4 Maintenance and Repairs
The maintenance of all plumbing systems, materials, appurtenances, devices or safeguards, both existing and
new, shall be maintained in a safe and proper condition. The owner, or his designated agent, shall be respon-
sible for the maintenance of the plumbing system. Minor repairs to or replacement of any existing systems
are permitted, provided they are made in the same manner and arrangement as the original installation and
are approved.

You are NOT doing "maintenance", you are replacing the entire system, which therefore, HAS to comply with current codes. Even it that were not the case, if your description is accurate, and we have only your work that it is, then it was NEVER installed according to codes, because that way has been illegal from many, many, decades.

Another thing that you may be overlooking is that often an experienced plumber can do work that will minimize the need to gut the place. Much depends on the experience of the tradesman and the way that the home is constructed.

Yes I understand what you guys are saying I agree it should be vented correctly no argument there.

The house is over 100 yrs old so no idea when that stack was run to the 2nd floor, my best guess is 1940s.
My father bought the house in 1965 and it was not altered since he bought it other than the washing machine connection was added by a licensed plumber in the 1980's and the bathtub trap and kitchen sink drain lines were repaired at some time using copper pipe tied into the cast iron with threaded fittings which are also not allowed anymore.

The entire crawlspace plumbing was also cast iron partially buried in the dirt and in 2002 it disintegrated and we had a licensed plumber re-pipe the crawl main line with 4" PVC but he left everything that existed up thru the floors and cut it and ferncoed onto that old stack and also ferncoed onto the other existing 1st floor waste lines that are copper from the 1st floor kitchen bath and washer.
It was all permitted and inspected when he did that crawlspace upgrade job in 2002 and they did not require him to update the entire house so was just curious how a job like this is normally approached.
The walls are plaster and lath which makes it even worse to start cutting things open to access pipes.

In reading the current code and looking at terrys diagrams it looks like I need to run a 2" vent from the crawl teed into the main horizontal after the 1st floor bathroom wyes into it, bring it up alongside the 4" stack and tee it back into the stack above the highest 2nd floor drains, but before it goes thru the roof, that would dry vent the 1st floor.

The 2nd floor items I could use that fitting shown at top of the stack so everything on 2nd floor ties in at the same level and then the 2nd floor venting would now all be dry thru the 4" stack.

Thanks for the advice and hope you guys all have happy holidays!