What issue is caused by adding insulation in the attic?

Adding insulation in the attic can lead to partially blocked eave ventilation openings, which is problematic for several reasons. Eave vents serve a critical function in the attic ventilation system by allowing cooler air to enter the attic space, helping to regulate temperature and moisture levels. When insulation is added haphazardly, it can obstruct these openings. This blockage inhibits the airflow needed for effective ventilation, which can lead to a host of issues including increased humidity levels, condensation problems, and even potential mold growth.

On the other hand, increased heat retention is a consequence of insulation, yet it does not capture the primary issue at hand, which revolves around air movement and ventilation. Improved air circulation is typically a benefit of proper venting, not a consequence of insulation obstruction. Excessive cooling of upper floors would suggest a reverse issue typically not associated with the attic insulation itself, but rather related to how insulation and ventilation systems are balanced and designed. Thus, the enhancement of insulation without regard for maintaining clear ventilation paths can significantly detract from the overall performance of the home’s ventilation system.