Hi there! First time posting here.

I am converting a 10′ x 10′ shed into a tiny house in New Haven, CT and trying to figure out how to adequately control moisture in the roof cavity, walls, and floor insulation. There will be no running water, so I am expecting humidity inside to be relatively low, except we were also thinking of only running heat (space heater) half the day in there to save energy, so I’m not sure what impact that cycling might have on movement of moisture and potential condensation.

WALLS
We have a bunch of polyiso rigid insulation that has been cut to fit between the studs, which I will spray foam around to secure in place and seal. People online say that poly sheet for vapor barrier is the old way to go but can trap moisture in the wall and is generally not needed. People say air barriers are much more important, but since the inside won’t be that humid I’m not sure this is essential either. Won’t the humidity in the wall be somewhere in between the outside and inside humidity no matter what?! In New Haven, outside humidity seems to range from 60-70% average throughout the year–in other words, HIGHER than it will be inside, so wouldn’t I want the humidity inside the walls to be closer to the internal humidity? And therefore not have a vapor/air barrier?

FLOOR
I laid 1.5″ of NGX underneath the floor. Trying to decide whether to leave exposed or to paint or cover with poly sheet stapled to the joists. People online seem to leave it exposed from what I can tell.

ROOF
Not sure whether to go with a vented or unvented roof. Again, because I am expecting humidity to be relatively low, I’m thinking we may be able to get away with an unvented roof? Would it be helpful to simply add gable vents without soffit vents? Do I need to air seal the roof off from the interior of the structure?

Thank you for the feedback in advance!