The 2nd floor bathroom fan vents into the attic. (WRONG, I know.)
I've been in the attic, and I see that I could either:

vent to an outside wall
or
vent out the roof

this is what complicates deciding:
1) venting to the outside wall means running a duct some 20+ feet to
the outside wall. Once there, someone needs to get up on a ladder and
install the outside ventcap, some 26 feet up off the ground.

2) venting out the roof would mean (maybe?) cutting a hole in the roof,
and getting up there and so forth. I'm not keen on cutting holes in my
nice roof, if I don't have to!

Question;
I have existing roof vents that vent the attic passively. Could I run
a duct TO one of those roof vents? If the vent diameter was larger
than the fan ducting diameter, I could still get some venting of the
attic via that roof vent. But, if the ducting is the same size, then
I've lost one roof vent....

suggestions?

If it's just an attic, why do anything? Our house is similar: stove and
both bathrooms vent into an attic space. It adds a little moisture, but
that's about all.

wrote:

The 2nd floor bathroom fan vents into the attic. (WRONG, I know.)
I've been in the attic, and I see that I could either:

vent to an outside wall
or
vent out the roof

SNIP

Vent out the existing roof vent as the best choice,
all things considered. Maybe it can do double duty
and still vent the attic as well.

Venting direct to the attic space can cause mold growth
on the sheathing and rafters.

Jim

pegleg wrote:
If it's just an attic, why do anything? Our house is similar: stove and
both bathrooms vent into an attic space. It adds a little moisture, but
that's about all.


This is a code violation just about everywhere and for good reason.
Putting moisture into a cold attic in most climates is a prescription
for disaster. The water condenses and leads to rot and mold problems.
There have been plenty of threads in here with people having these
problems from improper venting into the attic.

For the OP, it sounds like a roof vent is the way to go. 20ft to the
side wall is too far to get any decent air flow. While you may be
able to share the existing roof vent, I tend to doubt this will meet
the code reqts, so you may want to consider that.

In article , Speedy Jim says...

wrote:

The 2nd floor bathroom fan vents into the attic. (WRONG, I know.)
I've been in the attic, and I see that I could either:

vent to an outside wall
or
vent out the roof

SNIP

Vent out the existing roof vent as the best choice,
all things considered. Maybe it can do double duty
and still vent the attic as well.

Venting direct to the attic space can cause mold growth
on the sheathing and rafters.

And brings in warm air where it should stay cold during the winter, leading to
problems like ice dam formation. If you live in a cold climate.

Banty

"pegleg" writes:

If it's just an attic, why do anything? Our house is similar: stove and
both bathrooms vent into an attic space. It adds a little moisture, but
that's about all.

Well, until the mold starts growing.

An inspector will flag venting that stuff into the attic faster than
you can say "attorney's approval letter" when yo ugo to sell.

Best Regards,
--
Todd H.
http://www.toddh.net/

I'm in Chicago, where we should have better than R 38 up in the attic.
Winters get very cold. Because of this, I don't EVER run the bathroom
fan, but instead open a window in the summer, or keep the bathroom door
open about 6" in the winter, and keep the HVAC fan on, instead.

someone I know suggested venting the bath fan into the plumbing stack.
I'm wondering if that would be a code violation or not... The stack
does vent out the roof! :-)

writes:

I'm in Chicago, where we should have better than R 38 up in the attic.
Winters get very cold. Because of this, I don't EVER run the bathroom
fan, but instead open a window in the summer, or keep the bathroom door
open about 6" in the winter, and keep the HVAC fan on, instead.

I'm in Chicago too. When I purchased my current home, my inspector
noted the bathroom vent situation and told me I'll want to fix that
post haste. I ddi. I have R40 insulation in the attic. I do run the
bathroom fan to remove the moisture from teh living space and
eliminate moisture mold needs to grow.


someone I know suggested venting the bath fan into the plumbing stack.
I'm wondering if that would be a code violation or not...
The stack does vent out the roof! :-)

Big heaping steaming code violation. :-)

Tapping into the stack to your exhaust fan is an excellent way to have
your exhaust fan become a nice conduit for sewage gases to get into
your living space without a P trap sealing it off.

Look in the yellow pages for ventilation folks and have someone come
out and install a roof cap and get it fixed correctly...and consider
using your exhaust fan to get that moisture out of your place. With
the liability mold has become, the last thing you want is to give
buyers any reason to freak out about the possibilities more htan some
already do.

Some of the same folks who insulate attics do this sort of work of
installing roof caps.

--
Todd H.
http://www.toddh.net/

In article .com,
wrote:

Just moved to a 25 yo home with bath fan vents into the attic. Got
panic for a little and then had a roofer cut a hole in the roof,
installed a "bonnet" cap and attached the 3" duct, painted and sealed.
This was for 200 bucks. The roof was 3 yrs old composition shingles.

Was worth it.

The 2nd floor bathroom fan vents into the attic. (WRONG, I know.)
I've been in the attic, and I see that I could either:


2) venting out the roof would mean (maybe?) cutting a hole in the roof,
and getting up there and so forth. I'm not keen on cutting holes in my
nice roof, if I don't have to!


suggestions?