I have a 2nd story bathroom which is a little too humid unless the window is left cracked all the time, greatly decreasing the efficiency of our HVAC system. I would like to install a bathroom fan with a timer switch but want to make sure the humid air is ventilated safely and in a code-compliant manner. Home is in california, if that makes a difference.

Venting through the roof is not an option, the 2nd story of our home is covered in solar panels and I don't want to risk damaging anything up there.

In the picture below I have highlighted possible locations for an external through-wall vent for the bathroom fan ducting. Locations #1 and #2 are clearly too close to the gable vent. Location #4 is also directly below the gable vent, which worries me that warm humid air may be drawn back into the attic.

Locations #3 and #5 seem like the best option available. Is there anything wrong with this approach? Would this be a violation of any building codes for a bathroom exhaust vent?

potential wall vent locations

1 Answer 1


I would be using position 3 as position 5 is close to the window being that high up it will not be a problem for the condenser and compressor unit for your AC / heat pump I would agree the other 3 positions 2 at the vent would allow the moisture to be sucked into the attic space and the one over the window is two close as #5 is to 2 windows so I would say #3 is the best option.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.