adding shower

I 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? Thanks for any advice. Rob

Every trapped fixture needs a vent.

You didn't ask, but just in case you are not aware, a shower drain is required to be 2". Tubs are OK with 1-1/2".

RE : Shower Vent

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?