I'm puttin in a toilet for a friend,who doesn't want to cut into her concrete floor but would rather put in a sub or raised floor instead.I was going to use 6" boards to raise the floor higher then tie into the main and I was wondering if I could use 3" pipe because I only have 2" of the main that is above the concrete floor to use as a nipple to put a 3" y connection in for the toilet to drain into.or do I need to raise the floor even higher/

Hi Lucas

3" is the minimum pipe size for a toilet drain. 3" pipe is also the minimum drain size for an entire bathroom group (toilet, sink bath/shower), so no issue there, for sure! Just be sure to run the joists parallel to the pipe if possible... eliminate notching/drilling, etc. as much as possible. How are you planning to VENT the toilet... via the sink drain/vent? Let me know, OK?

Another option would be to consider installing a macerator pump system like the saniplus system. If you guys go with this system you'll only need to build the floor up under the shower (if installing one)... check it out @ www.saniflo.com

Mark

I only have 2" of the main that is above the concrete floor to use as a nipple to put a 3" y This doesn't make sense to me. You have 2" of the main sticking up from the slab. correct? Why put a wye on it? You're not giving me the entire story are you? Will a permit be pulled on this job?
What's you neighbor really wish installed? Half bath? Full? Normally you'd put a elbo on the stub up to bring it over for a drain and that would eat up the 6" before you ever got to the closet bend, Something's not adding up here. Would you care to share? Tom