Hope is almost always like “frosting on a turd.”
People often ask me if it is OK for bathroom exhaust vents to terminate in the attic. There was a period of time when lots of builders considered the attic “outdoors.” Well of course, it did not take too long to figure out that the attic environment is anything but “outdoors.” If the attic was outdoors, the temperature and humidity would be the same as out doors. We of course now know that temperature and humidity can vary widely in the attic and this is why proper ventilation of attic spaces is so important. We do not want to trap moisture in the attic but instead provide a pathway for it to escape. If we terminate bathroom, kitchen and dryer vents into the attic we obviously risk introducing more moisture into the attic than even the best ventilation system can remove.
Over and over I find attics that cannot handle the moisture that is being added to the attic space. A vent fan that is not properly terminated to the exterior at a cap with a back draft damper, or one that has become disconnected, can add a lot of moisture into the attic—especially in the winter. This can contribute to mold and rot in wood structures as well as contribute to ice dams.
I still find lots of homes from the late 70’s and early 80’s with vent ducts that merely aim at a roof vent. This method I consider the “Hope” method of venting. The installer is “hoping” that the air will simply find its way out through the waiting roof vent and then to the exterior. This next picture is perhaps one of the best improper vent terminations I have come across. It is pretty obvious that the screen in the roof vent is completely caked with lint.
There are two problems with this approach. First of all, over time, the vent screen will become clogged with lint. This will be the end of the hoping and now all that moisture is going to stay in the attic—guaranteed—creating the anticipated turd of a result—mold and decay/rot in the roof structure. The second part of the equation is that now the roof vent will no longer function to do its job and is being burdened with even more moisture than it should have to deal with to begin with.
It is important that your inspector verify that all of the vent fans in the home properly terminate to the exterior whenever possible.
If you look back at the picture of the vent you will notice that all of the plywood has been painted white as part of a recent mold remediation.
Why was this vent not fixed as part of that remediation?
Dang—there goes hope again!
By Charles Buell, Real Estate Inspections in Seattle
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