Subscribe or Renew Membership Subscribe Renew

bath exhaust vent

merrimacdave's picture

Hi: I'm installing a new bath exhaust. The old one was vented into the attic. I have a choice of venting through the roof (shortest route but the roof pitch is only a 3 1/2 and I live in the Northeast so snow may be a concern, The next closest route would be to vent to the soffit.(easiest option but not the best). The last option is venting out the end wall of a dormer but it's about 18 feet away. There's no clear winner to me. I wondered if someone could give me some insight. Thanks

up and out (post #206324, reply #1 of 7)

I would think going straight up through the roof would be the best option, there are plenty of cap options out there to prevent snow problems. If your really concerened a 1way flapper and a stack are easy enough.

I dont know about regulation for where you live on exhaust port to roof and slopes though but I dont foresee any problems.

Good Luck

dave (post #206324, reply #2 of 7)

In a cold winter environment, condensation in the pipe can be as important a consideration as the exhaust location.  Yes, insulation around the pipe will help, but one additional step will go far in limiting damage caused by water dripping back or collecting in the pipe.  Install a timer to operate the fans use.  And use as quiet a model fan as you can afford.

In many cases the fan is on the same switch as the light.  You shower with light on, leave the room and the light is switched off, often too short a time to clear the room of humidity and for sure, not enough time to clear the vent of moisture.

Straight up, condensation drips right back down to the housing.  Long horizontal run, and it can collect in a low spot.


Running the fan longer than the few minutes in the bathroom is a good way to limit condensation problems.


Best of luck.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


That's a perfect situation to (post #206324, reply #3 of 7)

That's a perfect situation to use a fan-tec remote fan with insulated flex duct and go out the doormer.  With a longer run it deadens sound so all you will hear is the little backdraft flap open when the fan is on - it really is that quiet.  

If I could edit my location it would say I'm now in Reno :-)

Go thru the roof with a high (post #206324, reply #4 of 7)

Go thru the roof with a high profile jack and put a loop or a trap in the duct work so the condensation doesn't drip back.

same (post #206324, reply #5 of 7)

I was thinking to do the same thing with my bathroom now.