Best Practices: Bathroom Venting
My HVAC guy was just out here today to install mini-split line sets in the walls and to install dryer vent and bathroom fan vent. I had to be at work and because he is so busy I had to practically twist his arm to get him here, I just left everything he’d need and a key and discussed via text yesterday any previously undecided details. I didn’t think to question the bathroom fan venting…assuming he would vent it straight up through the roof along side the fan.
When I returned home I noticed they had run the vent…which was previously installed by electrician, very close to the ridge beam (high point) in the bathroom (cathedral ceiling)….with the vent….which happens to be very large….down the entire length, and taking up most of the width… of the rafter bay (appx. 12 feet in length) with the roof vent attached to the underside of soffit, aimed toward the next rafter bay over.
“Just a girl” here…but this is not what I expected and I’m wondering if I should ask him to change it so it vents out the roof instead. My concerns are:
1. Will warm damp air be able to easily escape “down hill”?
2. There’s little space left in that entire rafter bay for insulation
3. Wouldn’t any damp air that is able to escape “down” that 12 foot length get sucked right back up into the next rafter bay over once it leaves the exterior vent?
I won’t exactly be “thrilled” if this ends up costing me money to have it changed, but it’s money I will gladly pay if necessary. This just intuitively looks “wrong” to me, but I have no experience in “what does and doesn’t work in practice“. If there’s any chance that this could be a problem waiting to happen, I’d rather pay now and avoid the mess.
I did text him just to ask him why they did it that way…thinking the vent size may have been an issue (a whopping 6″ vent in a 10” rafter bay) but he told me they didn’t want to cut through the new roof and wanted to avoid potential leaks down the road (this sounds odd to me….Aren’t roof vents standard practice for bath fans?) I have not yet asked him to change it.
Would truly appreciate any advice/comments!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part