The correct placement of a 2nd story through-wall bathroom vent


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

Best Answer

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.