Renovating my bathroom (Bathroom A) and have all walls exposed to the studs. Power runs from the attic to the light and switch of the adjacent bathroom (Bathroom B), then to the light in Bathroom A, then from the light to the switch with a 14/2 wire (b/w). I want to add an exhaust fan controlled by a separate switch (preferably humidity sensor switch).
I initially thought I would run a new 14/3 from the exhaust fan to the new switch, and then connect the new switch to the existing switch with a pigtailed black (hot). But with the existing switch being at the end of the line with a 14/2, I don't think this is possible b/c that means both wires are operating as "hot" between the light and the switch, right? So how do I go about this? Do I run a new 14/3 from the light to the existing switch, then pigtail it to the new switch?
Excuse anything above that doesn't make sense, I'm a DIYer that is newer to electrical work and hoping this is feasible without hiring an electrician. Any help, especially a diagram, would be amazing!