Proper attic ventilation

A homeowner in central Alabama wrote in with a problem many people with vented attics run into: condensation and mold forming under the insulation, right on top of the ceiling drywall, across 3,000 square feet of attic space. The attic has powered fans in each section pulling air through soffit vents, but that setup hasn't solved anything. A moisture meter check found the attic air at 80% relative humidity, compared to 47% outside, which points to a real moisture problem rather than just normal weather.

Two mold remediation companies looked at it, and the advice was mixed. One had no suggestions for the attic itself. The other recommended adding more fans and pumping air from the living space into the attic to dry it out. That idea deserves skepticism, since pushing indoor air (which usually carries more moisture, especially in a humid climate) into an attic can make condensation worse, not better.

Attic condensation problems like this usually come down to where moist air is getting in and how it's escaping, rather than just needing more raw ventilation. Common culprits include air leaks from the living space into the attic, humid outside air getting trapped, or a ventilation setup that isn't actually moving air the way it's supposed to. If you have a vented attic and notice damp insulation or dark staining on drywall from above, it's worth having someone look at the whole picture — how air enters and leaves the attic — rather than just adding fans.