We are remodeling a bathroom and have an exhaust challenge. I've been searching previous posts and don't see our particular problem addressed -- and there are discussions in new build, bathrooms -- so let me know if I should post elsewhere.

We live in the NE. This past year we didn't have a lot of snow, but the previous year -- our roof was shoveled off several times.

Our bathroom is approximately 15' x 8' with a cathedral ceiling. The shower will be a 60"x36" alcove located approximately in the middle of the room (along a length wall) with glass sliding doors, but with space between the top of the door and the ceiling.

Our current shower vents out the soffit, which is not large enough to let a 4" vent out (its a pretty narrow soffit, 1976 house).

Our current ceiling gets moldy (when we remodel, we'll remove it and see if we can figure out why).

So the question is -- how to vent the remodeled bathroom. The options identified so far are:

1) vent as is currently vented (vent fan/light is just outside shower, vents about 5' length out the soffit); concern is that its not really venting enough and that exhaust just runs along the soffit and back up the roof vents (and that's the source of the mold, but we don't know for sure)

2) place vent on outside wall and vent direct to outside (however, the exterior wall is the short one, the cathedral ceiling in the bathroom rises from the outside wall, so we're fighting physics). Outside wall is about 78" high and rises up to about 12'

3) vent straight out the ceiling -- with a flush roof cap -- it extends above the roof about 8" tops, and has a little "hat" on it so stuff can't fall in, etc. However -- what happens when we get snow and it is covered?

I don't know if anyone has experience with venting cathedral ceilings and would make a recommendation (vent directly above shower or slightly outside in bathroom so it could also serve to vent for smells); alternatively, what pro should we call for a consultation on this?

Thanks in advance!