Hey everyone! I'm reaching out for some insight on my attic humidity issue. Two years ago, I had my attic reinsulated and all air gaps sealed up. We went all out with spray foam, dome caps on fixtures, vented bathroom fans, and even added insulated storage solutions. Everything was great until about 6 months after the work, when I discovered mold up there for the first time in ten years of owning the house. A mold inspector suggested that we might have over-insulated, blocking necessary airflow. I got roof quotes and learned that I'd need a powered attic fan due to insufficient ventilation from the soffits and ridge vents. After installing the fan, I've been monitoring humidity with Wi-Fi sensors, trying to keep it under 60%—which mostly works unless it snows or rains. Now I'm anxious because I worry that high humidity on those days could lead to more mold. Am I okay to let humidity exceed 60% with the fan running, or is that risky? If it is risky, what should I do? Who would I need to consult to find a solution? Feeling frustrated with previous contractors' advice! Thanks for any help!
1 Answer
It sounds like you've done a lot of work on your attic! Just to clarify, humidity itself isn't the direct cause of mold; it's the condensation of that humidity that leads to mold growth. When warm, humid air comes into contact with cooler surfaces, the moisture can condense and create the conditions for mold. The good news is that having your fan running can help keep air moving, which may prevent condensation—even if humidity levels rise above 60% on rainy or snowy days. Just ensure your gable vents are open to allow airflow from the fan!
Exactly! Keeping the gable vents open should help the fan do its job. Trust your setup a bit more and remember, moisture becomes a problem mainly when there's no air movement.