I am putting in a master bath off the master bedroom which is on the 2nd floor. The problem is the closest 4" main waste stack is about 16' away from where the toilet is. I will try to explain this from the perspective of if you were actually sitting on the toilet taking care of business. The 90 degree closet bend will head left from the toilet going through the joists below (joists are parallel to my legs as i sit on the toilet). The joists are big enough to handle the 3" drain going through them with the allowed drop (1/8" per foot and staying 2" away from the top or bottomedge of the joist). So after about 6' of going to the left, I will use a gradual sweep of 90 degrees to head back 11' behind me (underneath another bedroom and then I will sweep 90 degrees to go down the wall I am going to modify to handle the 3" drain stack. Now I will head down through the first floor and end up in the basement about 4 feet from my stack.

With that said, you can see how it is quite a distance and alot of turns from my main cast iron stack. I plan to run a 1 1/2" vent immediately after my closet bend that will run back to the wall behind the toilet and up through the attic into the roof (not worth messing around sending a horizontal vent run alllllll the way across the attiic).

I can draw a picture if my explanation is sub-par. Thanks in advance for any help.http://www.kreativdesigns.com/toiletdrain.jpg

OK, sounds like a plan. I am guessing you are going to penetrate the roof with the vent. Also, are you going to have a lavatory in this room?

Looks good to me. I would use long sweeps if you have the room. Doug asked about a lavatory. If you're planning one then a separate toilet vent will not be needed. As for the vent you may take it up into the attic and revent back into a existing roof vent instead of going through the roof.. I would also increase the vent to 2" if it doesn't cause a problem. Good luck, Tom

I am guessing a 'chamber' is a bedroom? You are adding a toilet with no handwash sink and eliminating the closet altogether? I hope you are not ever planning to sell this house.

Thanks for the speedy replies everyone. I can easily change it to a 2" vent for sure. I just showed you a quick sketch of my plan on top of the old drawings of the house. The bathroom plans thatI have drawn up are actually much more detailed and involved. The bedroom will still have a full walk in closet. There will be a sink and full tub as well as separate shower in the bathroom as well. The only thing I wasn't sure about was the drainage issue with the toilet, so that's all I drew. Again thanks for the super quick help and responses. This forum is a tremendous resource.
Mark

Just a note for tom.
Tom, when I lived in Florida I always used a 2" to vent a toilet. for a few reasons this was a good thing. first, it was what dad taught, i did not know why, just obeyed. second, when i started using a suitcase machine on the roof to clear a drain i was ever so grateful to see that 2" vent. Now that I live in the atlanta metro area I have discovered a few things. Up here the roof is higher pitched and rarely does anyone go on the roof, specially to clear a drain. It is simply too steep and too dangerous. Now that the code allows smaller piping for low flow fixtures hardly anyone is putting 'full size' venting in anymore. Heck, you don't even have to have at least a 3" vent anymore. i see in the code where your largest vent could be as small as 2" and your smallest vent can be 1 1/4". and they went so far as to even allow an 1 1/2" drain line and trap for a full size shower now. I think there will be lots of problems with it but some do it anyway.