Routing bathroom ducting
This is a little hard to explain but hopefully not too confusing…
I will be routing my bathroom fan exhaust through the gable wall in my attic, which is about 8’ away from the fan, and will be traveling perpendicular to ceiling joists.
The fan sits inside the cavity as most fans do I suppose. But I cannot just run the duct in the cavity until I reach the wall, since that would mean doing a 15-20’ run going this direction, and would exhaust out of soffit. No thanks.
So here’s my concern: In order to get up and over the ceiling joists before sloping it toward gable wall I need to take a hard 90° vertical up with my ducting right out of the fan, since the outlet is on the side of the fan as opposed to on the top of the fan… Won’t moisture get trapped right at that elbow before it can even get anywhere?
(Wouldn’t a fan that can route moisture through the top of the fan make a whole lot more sense?)
I cant really think of anything else to do BUT to route the ducting up and over the joist, then run it toward wall, and exit…
Will I need a higher cfm fan than what is req’d for my size bathroom? Any other options? Or is my situation completely fine and nothing to worry about…
I see a lot of pictures where the ducting is just routed either straight up through the roof. Which would still mean a hard 90°, just straight up, and I do not want to do that. Or it is simply routed parallel to the joist bay the fan is already in, then out the wall, or even boared through joists which I think might be a bad idea for me since I have 2×4 joists in this part of the house.
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