have an existing 1/2 bath in the basement (raised ranch). I am going to break up the concrete and connect the new shower drain into the main which is 4 feet away. My question is, since the main acts as a vent, is that sufficient to vent the shower without adding another vent as there is no close vent to tap into? If the 2" trapped shower drain goes directly into a 3" main dwv (4feet away) does it still need a separate vent or is the 3 inch main dwv sufficient?
You're gonna get the same answer as you were given on the Remodel segment. Every fixture/trap needs a vent.