"Bill Christens-Barry" wrote in message
...
I live in a one story house with an unfinished attic. Currently, the
bathroom fan is vented by a 3" PVC duct that passes through the attic
and out the roof. The attic gets cold (blown in rock-wool insulation
lays between the foor joists) and the humid air being vented from the
bathroom condenses. Unfortunately, the PVC is sloped the wrong way so
condensate is dripping back through the fan and into the bathroom.
Messy, and damage to the bathroom ceiling is occurring.

I'm planning to replace the fan with a quieter one with more volume, and
I'd really like to avoid having to put another hole in the roof, and I
also don't want to use the present ducting.

A builder who helped with some other renovations has told me that it's
ok to run the fan exhaust duct (it'll be 4" diam) up to just beneath the
ridge vent, and to allow the exhaust to vent through the ridge vent. Is
this likely to work, and is it an acceptable way of venting? I wonder
about blowback and about iceing during the winter.

Also, is it reasonable to insulate the exhaust ducting to minimize
condensation within it?

Thanks for any comments or suggestions.

Bill Christens-Barry

--
Wm A Christens-Barry, PhD
Equipoise Imaging, LLC

http://www.eqpi.net/eqpi/

This is a question for you local building authority. Personally I would
consider using the old pvc and insulate it. I would not want a fart fan
venting into the attic, cause around here that is not acceptable. Hence the
roof penetrations.

Your going to have some problems with the 3 inch pipe. Everything I have
seen recently is 4 inch or larger.

alternate solution vent to the eves.