# Bath Exhaust fan in vaulted ceiling assistance



## Dak Man (Jul 4, 2015)

in many ways you know the answer to your own questions. If you need a roof later on than you know to tell the roofers to watch out for the exhaust fan. 

What you need to know and failed to delegate is how big of a fan you need. 

I personally would not recommend installing a fan so close to the roof as it appears you have no where to truly exhaust it and the duct that is attached to the fan in the attic needs to be run somewhere, preferably to a soffit. 

You can't just install a fan and exhaust it into the crevice between to roof joints as you will experience mildew, possible condensation drip, etc..

I hope that helps.


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## gzill (Jun 18, 2015)

Thanks for the reply! I believe I got a 70 CFM fan -- which when I calculated the requirements, it was sufficient. Unfortunately, I don't have the dimensions or the fan available to me right now to be certain -- but I remember it working.

My options for venting was to either put a roof vent cap about 6 inches from the unit (within the same hole) or pull a length of duct between the joists to the soffit. I think the easiest way would be to put the hole in the roof directly next to the unit -- not sure what others have done in this situation.

I edited the picture to show what I was thinking of doing with the fan and the vent to roof cap.

THanks


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## Dak Man (Jul 4, 2015)

Thanks for the question. 

*Bathroom* vent *fans* are rated by the cubic feet per minute (CFM) of air they move and should be sized to replace the air in the room at least eight times an hour. If your *bathroom* has an 8' *ceiling*, the CFM rating for your *fan* should be as least as high as the number of square feet (5' x 7' = 35 sq. ft.) in the room.


I've always exhausted to a soffit. Can't speak to through a roof with added pulling support but I'd have to believe it would work.


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## ChuckF. (Aug 25, 2013)

Other options:

-Build a kind of a picture-frame looking mount that would move the fan down a couple of inches. Might look ugly.
-Look for a remote fan; then what's in the ceiling would be just an HVAC duct and grille and a pipe leading somewhere where you could mount the fan itself.
-Look for a wall-mounted exhaust fan that can go right through an exterior wall.
-Look for a fan made for this application, where the back of the fan is your 4-5" pipe that can punch right through the roof sheathing above it and mate with a metal vent that can go on the roof. Such a fan may not exist.


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## gzill (Jun 18, 2015)

Thanks guys for your responses/ideas. Much appreciated.


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