Vents can be shared (between fixtures),wet vented, tied into other vents, stacks, etc, air admittance valves can be substituted in place of a conventional vent-to-roof (assuming at least one roof vent already installed).

A plumber can advise you on the specifics.

: : Do tubs & showers need to be vented

: Reply:
: Yes. All plumbing fixtures that have drain traps need vents, including toilets which have integral traps.
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