This is a picture of a million dollar house that has foam insulation within the attic area, but the soffit venting for the bathroom vents is just an Air Conditioning supply vent covers. I cannot find where this is NOT proper standards. The builder has installed these on ALL of their houses in the development. Just seems that during out hot and wet summer months that air will infiltrate these vents when they are not operating and cause mold problems within the bathrooms by reverse air flow.
AHJ rules on this but let them argue that install against
IRC 2006 M1501.1 Outdoor discharge. The air removed by every
mechanical exhaust system shall be discharged to the outdoors.
Air shall not be exhausted into an attic, soffit, ridge vent or
IRC 2006 M1506.2 Recirculation of air. Exhaust air from bathrooms
and toilet rooms shall not be recirculated within a residence or
to another dwelling unit and shall be exhausted directly to the
outdoors. Exhaust air from bathrooms and toilet rooms shall
not discharge into an attic, crawl space or other areas inside the
I agree that it has to exhaust to the exterior. But should there not be a damper on the vent? Not allowing for air to back flow? This is just a interior HVAC supply register cover.
The exhaust fan likely has a damper integral to itself. If there is a metal ‘box’ above that register that the duct connects to then I don’t see anything wrong with it. The register will likely rust within a few months but other than that it looks like it meets the code requirements to me, i.e. it does not simply dump exhaust air into the soffit area.
What about insects getting in?
Good point…dirt dauber heaven. No reason it couldn’t be screened though, it would take a little ingenuity to make it look good.
Up in Canada, there are at least 2 designed under soffit vent outlets with backdraft dampers sold. Don’t have any pictures though! Won’t have much time to look today, gotta work.
Still not the ones we have here but a start.