Bad Ventilation Can Make Your Attic Mold Pardise

In my last blog I talked about how the attic is a system in which all parts must work together to prevent the formation of ice dams.  I’d like to expand on the theme of the attic as a system and talk about how it can be the perfect environment for mold if not configured correctly.  Just as proper ventilation and insulation are required to regulate attic air temperature, exhaust vents that pass through the attic must be configured correctly to regulate moisture content.

There are many things that can be routed through the attic such as waste vent pipes, combustible appliance exhaust, HVAC ducts, etc.  This blog will focus on a major problem causer: the improperly terminated vent.  In the picture above you can see a flexible air duct with a vent hood that directs exhaust into the attic.  This is incredibly common, and many people think it’s fine since the attic is vented to the exterior.  The problem with this setup is that it routes moisture directly into the attic.

Airborne mold spores are everywhere.  All they need to grow into mature colonies is an organic surface, like wood, and moisture.  Attics have an abundance of exposed wood, so terminating a kitchen/bathroom/dryer vent in an attic is practically inviting mold to grow.  The picture above is from a DIY bathroom remodel that was completed to make the home more marketable.  The bathroom was not in use in the vacant home and problem was discovered before mold could take hold.

If you’re considering a bathroom remodel, adding a vent hood in your kitchen, or just not sure where existing vents are terminated, take some time to verify proper routing to your home’s exterior.  Once mold problems develop they can be very costly to repair.  This simple problem is easy to spot and can prevent big problems if found early enough.  Check your attic!