Corkscrew Shaped Skylight Tunnel.

jimmys

I don't think it needs to be high cfm, but I think you need a fan up there. A small fan would not cause chilling drafts, but would move the moist air out. I'd run it on a humidistat, since people don't turn fans on, for various reasons.
Years ago we ran a vent fan right over a shower, straight up through an attic and roof. Come winter the duct (yep, it was insulated with fiberglass over the galv pipe) condensed water and dripped it back down on the owner in the shower. Had to fix that...
Jim

greg24k

Fan will create a bigger problem, fan should be installed near the shower on the flat ceiling, not inside the skylight chase.

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