I am planning on adding a bath and need to know how far away from the main stack can I place the toilet. The plan is about 9 ft away. I have enough room for the 1/4″ per foot, but is 9ft too far. Also, will I need to add a separate vent close to the new toilet so that the new toilet flushes correctly. Second, for the sink/shower drains: Can I tie in to a washing machine drain directly under the new bathroom. The washing machine has a trap on it and I would tie into the drain line after the trap (downhill).
I don’t understand if there is a question about the 9 feet for the toilet; they require in my state a vent no farther than 3’6″ from the water closet flange.
You can tie into the washing machine drain only if you are NOT washing a vent.
Check with the local codes in your area to see what is enforced.
That is what really counts is your local jurisdiction.
Even if your code says 6′ are more I would put a 2″ vent on the toilet. If your washing machine drain has a vent on it connect below the tee, if it has no vent then vent it and connect below tee, best is to check your local code.