Best place for bathroom fan in slopped ceiling without compromising insulation

[Andrew_in_Ottawa]

I am trying to add a bathroom fan in a ceiling with a slopped ceiling (low points are exterior walls, high point is middle of the house). I am wondering where the best place the place the fan is given that I have minimal space for insulation (just between the 2X6 ceiling joists as there is no attic). If I duct the fan down from the middle of the room to the exterior wall I will have minimal insulation in the area where the ducting will be. Would this be a problem from a heating point of view (I know very little about heating)? I am in Ottawa Canada and it gets bitterly cold in the Winter. Should I be buying ducting that is insulated?

Thanks,
Andrew

 

[Reach4]

If I duct the fan down from the middle of the room to the exterior wall I will have minimal insulation in the area where the ducting will be.

What does that mean? I have made a sketch, where blue represents roof and outside wall, and I doubt that any of the lines represent what you are picturing.

 

[Sponsor]

 

[Jadnashua]

Trying to push hot, moist air down the slope of the roof, and, essentially compromising the small amount of insulation available there isn't a great idea. Venting directly through the roof with an extension to keep the outlet above the typical snow depth there might work, or a through-the-wall unit, but being at a lower portion may not be quite as efficient in moisture removal, but would be less prone to convection losses. The air dampers on those things are never perfect, and can create a draft.

 

[Andrew_in_Ottawa]

In terms of how the diagram looks the roof and exterior wall are exactly that angle you have and the ceiling is slopped exactly in line with the roof line. There is no attic, so the only space between the drywall interior ceiling and the roof is the space provided by the rafters (which I believe are 2X6 - I haven't confirmed that yet). My major issue is the minimal space for insulation. I considered going through the roof, but I was worried about snow build up and the potential for moisture to come back down (right now there is almost a foot of snow on the roof). I considered the wall idea, but the highest point is 12 feet high in the most interior point of the room and the lowest point is 7 feet on the exterior wall where the fan would need to be for that to work.

 

[Jadnashua]

Nothing says you can't run the outlet of the exhaust up 2-3' or so with a cap on it. Any roof penetration needs to be properly done, but if it is, should be problem free.