I am moving my toilet to the other side of the bathroom, and adding a tub. My bathroom is very small 5' X 7' and I only have one existing vent. The vent is 2" in the wall and is 3" coming out of the roof. Anyway, I was wondering if this piping plan would work, or if someone has a better way to do it, I would sure appreciate some help.

I did submit the question before, but that was before I opened up the wall and found the vent in a different place.

That's the way I'd lay it out. The tub/shower will be wetvented by the lavatory vent. I would make the 3"elbo a sweep, (long or short) to reduce any chance of clogging. Nice layout in a small space. Good thinking! Tom

Thanks for the tip (especialy about the sweep thing! )

I had to change my plan becase the sink drain was not in a good position to attach to the toilet elbow. Here is my new plan, see any problems I want to glue this up tomorrow so any comments would be greatly appreciated. Thanks

Do you live in canada? That 3" coming out of the roof sounds like you're in a region with a colder climate in the winter prone to frost. It looks like you have your toilet at the top of the stack which really isn't the best way to do it id think, if you could draw a plan view (above view) of your washroom with fixtures and dimensions I could get a better idea of what you're up against

with a 5' x 7' washroom id say no matter what configuration you choose, stack venting would probably be the best way to do it (the first way you had it drawn), just make sure your toilet is downstream of everything else and no furthur than 5' from the vent (the change from horizontal to vertical) and the same goes for the tub

The reason I am unable to do it the way I drew it first is that I have to go across floor joist to get to the toilet drain from the sink, which means I have to across floor joist from my shower. Now I have to lower my toilet connection to get the water going downhill, and my toilet is at the end of a long run. So is everyone saying that my second picture is not advisable? Thanks all for your help, it's great having a resource like this to depend on!

I'm not saying it won't work but I'm not comfortable with all the elbows being used and the size of the tub drain. It should be 2 inches. I hope you'll use 45's and sweep elbos to make your turns.
On another note I don't understand Big Kills post;

" do you live in canada? that 3" coming out of the roof sounds like you're in a region with a colder climate in the winter prone to frost. It looks like you have your toilet at the top of the stack which really isn't the best way to do it id think."

Number one, the vent's 2" not three and two, Big kill must live in a warm climate or he'd realize that toilets don't freeze up just because they're on the high end of a vent stack.
The sewer gas being exhausted is warm and lighter then air so it will raise
And not allow freezing temperatures to venture into the house. And why just the concern with a toilet? The lavatory trap is much closer to the vent then the toilet is. But I don't think you have to worry about either one.
Cheers, Tom

Thanks for the info, I just wanted to make sure that when I put it all together that It has adequate venting. And when I flush the toilet it won't fill the tub. This is the second bathroom that will not get used much, as far as location, I live in Buffalo and it does get pretty cold here.

As far as the vent goes, I was wondering why it came out of the roof 3" and was 2" in the wall.

It comes out of the roof 3" because of the possibility that the vent may be constricted during cold weather due to frost, snow, ice... thats why I was curious as to whether you live in canada for plumbing code reasons