To cut in a drain, you would install a wye fitting, and then a wye fitting for the vent. You will need a vent after the shower p-trap and then you can wye it into a waste line.
The vent goes through the roof.
i want to add a shower to our 1/2 bath and need to figure out the drain design. the drain would tie into the main exit between the washing machine (ahead of the shower) and the toilet (after the shower). there is another bathroom and kitchen ahead of this as well. sooo how do i keep the shower drain from becoming a geyser? is it just a matter of installing a Y correctly? this is all on the main floor of the house and all in a line along the back wall of the house - like so: bathroom (tub/toilet/sink) -> kitchen sink > washing machine > bathroom (toilet/sink). i am not above having a PRO do this for me but if something a realtive novice can accomplish, i will do it.
ALL plumbing is a "matter of installing the fittings properly". Between installing the proper "Y" the proper way, and installing a proper vent, it is probably NOT a diy project.
Licensed residential and commercial plumber