Should an aluminum 3/8" duct from a bathroom fun be connected with a soffit
vent with some kind of boot?
Mine is laying just right next to the soffit vent and partially blows inside
the attic. This causes a moisture in the attic. I also suspect this is why
there is an ice damp on the roof above that place...
I guess it shouldn't be like that..
It's common enough to just run the vent duct from the fan out into the
soffit and let it blow. Mostly this wouldn't blow back into the attic but I
suppose it depends on how wide your overhangs are. I do this with my fan
and it doesn't make any problem either in the attic or on the roof.
However, if you are getting melting and blowback into the attic, you should
get an appropriate hood for the soffit. A quick google check shows that
these are readily available.
It's really preferable to vent it through the roof or a side wall
using either a roof jack or wall jack. Even if you use a fittling to
vent it through a screen in the soffit, much of the moist air can make
it's way back into the attic because the normal flow of air is in
through the soffit, and out through the ridge. You really don't want
all that moisture in your attic. Not only does the heat cause
problems like you describe, but the warm moist air will condense on
the cold roof surface, which can lead to rot and mold.
You see a lot of bath vents done this way because it is easier and
cheaper. But they violate all the guidelines for proper venting.
I have a hipped roof (no gables) and a ventilated drip edge (no venting in
soffit itself, no blowback)
But my builder didn't even put ducting on the bath fans. (I'm second owner)
I installed _insulated_ ducting to a soffit vent like this UEV 4
Don't forget to put insect screening on it.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.