Help with new bathroom venting...

Hello, just stumbled upon this site today and it seems like a great place to get help on plumbing.....

Im putting in a new bathroom in my basement. There is already a toilet flange installed in the concrete (that for some reason they ran the drain from my furnace to?). Also, there is a boxed in opening thru the concrete slab down to the dirt with a 2" dwv pipe capped off sticking out. This pipe goes back under the slab opening only about 1 1/2 ft. and connects to what I believe to be the main drain leaving the house.(also, this 2" offshoot was not glued to the main drain, just shoved into the T fitting). The way it is layed out, I assume its for a shower. Unfortunately the sink will have to be installed further away from the toilet and shower on an intersecting wall. I have a bathroom and a half upstairs that are back to back and everything appears to drain to a main stack that goes down through the concrete basement floor. It is the only drain pipe. When I looked on the roof there is only one vent stack, however it is not coming from the main drain that goes down thru the concrete floor. All the upstairs fixtures feed into this drain, there is no stack that goes continuously from the basement floor through the upstairs ceiling and out of the house. So, it appears that every fixture upstairs must have its own vent that goes up and ties into to one vent stack thru the roof. My washer and dryer are downstairs and the washer drain is not vented. This house is only 8 years old.

My questions are,

Can I put in a trap under the new tub and drain it to the 2" pipe coming out of the hole in my slab?

Is it safe to assume that since there is a toilet flange concreted into the basement floor that just hooking up the toilet without a vent connected to it is ok?

The sink is going to be about 11 ft. from the main drain, can i run the sink drain horizontally around the wall to the 2" drain pipe im gonna use for the tub, and drain the sink there as well with a Y? (i know the 1/4" a foot rule)

It would be impossible for me to run a new vent stack to the roof without tearing out my upstairs walls. Can I use those "auto vent" devices on each fixture instead?

Sorry for all the questions, but I really want to do this right and "how a real plumber would do it". Thanks for any help you can give..

Todd

P.S - I had some details wrong about the current plumbing so I edited this message.......

bump..........Help please???

I'm not a pro...all of the items in the basement need to be vented, so no, you can't just put a toilet on the toilet flange and go for it. Note, a drain for a toilet does NOT have a trap in it, so just dumping your furnace's condensate into the hole will allow the water to go away, but also leaves a direct opening for sewer gasses into the house - not a good idea. It appears that the opening in the cement is for either a shower or a tub. Normally, they put a trap in, but thatdoesn't appear to have happened, yet. I'm surprised that they didn't glue it into the fitting and then cap it off. I'm also surprised that you haven't had any leaks. A 2" line is good for either a tub or a shower (the shower needs the 2"). You should be able to run a new line for a vanity sink and run it into the same line as the tub. From what I read, you will either have to run a new vent line all the way to the roof, or at least above the drain level of the items feeding into the main stack. Eventually, one of the pros will have compasion on you and fill in the blanks or correct me!

drainage

Most of the things you are asking are impossible to diagnose without being there. Done in one manner they might be okay, but done differently could be completely "illegal".

How about if I post pictures and drawings of exactly what I have? Would you all be willing to help then?

Thanks,
Todd

update.....

Hello,

I decided to draw my current and proposed layout of the DWV system. As indicated in the picture key, I could not verify 100% the vent lines for the current fixtures. There is only one stack going thru the attic to the roof. And since the main waste stack that drains everything does not go straight to the roof, (which seems odd compared after researching) all the speculated vents must tie together in the walls.

After reading up on AAV's, could the layout I have proposed be sufficient? If you need anymore info just ask.......

Thank you to anyone who will take the time to help me out.

Todd

Deb

"Sorry for all the questions, but I really want to do this right and "how a real plumber would do it". "

"Can I use those "auto vent" devices on each fixture instead?"

Real plumbers don't use auto vents. (Not really necessarily true, they are approved in some places ). I live in an area where auto vents are not allowed. If we cannot run a vent up and connect with another or through the roof, we do not do the plumbing. Venting is part of the whole plumbing deal. If you cannot vent it, you shouldn't install it.

Actually I never put a trap in for a tub or shower on slab. The location of the trap has to be exact. The norm is a concrete block-out with a horizontal trap arm that you cut, 22, 45, or whatever you need to locate the p-trap directly under the drain of the tub/shower you install.

"...there is no stack that goes continuously from the basement floor through the upstairs ceiling and out of the house"..." This is not how venting works. Every fixture must be individually vented--fixtures can share a single vent, but every fixture must have a vent, within a specified distance from its p-trap, with specified fittings, run in specified ways. The way the vent is run generally depends on the amount of grade you have. When grade is a problem, vents have to be run in special ways. The vent for the toilet must be within 6' of the top of the flange (UPC), the vent for the tub within 5' of the trap if you run a 2" trap arm and trap, within 42" if you run a 1-1/2" trap arm and trap. The lav within 42". The vent must be located in certain places within the drainage system. They cannot come off a branch like in the drawing. There is alot to this venting stuff. I would advise that you call a plumber. There is more to it than we can most likely convey in a forum like this.
Deb
The Pipewench

aav

The AAV by the cleanout has absolutely no function. The "red" toilet does not seem to have a vent, and the sink and tub with AAV's may work, but being downstream of the remainder of the plumber could be subject to positive pressures because of air being pushed ahead of the water from upstream. AAV's only be used when a conventional vent is "impossible" to install, not when they are just more convenient.