When was the last time you went up in the attic? Maybe last December when you brought down the Christmas decorations or when you needed to get the air mattress for a surprise guest? Let’s face it, attics aren’t visited very often. This is part of the problem when it comes to discovering mold growth. We could go years without noticing a build-up. That’s why it is so important to inspect your attic several times a year to make sure there is no accumulation of moisture. Mold needs moisture to grow. So what could be contributing to this growth? Let’s look at several common causes of mold in attics.

Inadequate Ventilation

Poor ventilation is one of the most common causes of mold in attics. If your attic is not properly ventilated, you have the perfect conditions for mold growth. Hot air always rises, so it will naturally make its way to the attic. With nowhere to go, it lingers in that space, causing moisture to form and leading to mold growth.

Contributing to this problem is often improper insulation. If the wrong kind of insulation is chosen or if it is installed improperly, this can cause moisture from the lower levels of your home to rise and get trapped in the attic. That’s why it’s so important to allow for proper ventilation! Don’t forget to make sure vents in the soffits are not blocked by insulation as well.

Bathroom Venting Issues

Bathroom vents and kitchen/ dryer exhaust fans should never terminate in the attic! They should always be vented to the exterior as they are designed to pump moisture OUT of your home. If they are vented through the attic, they pump warm moist air where it gets trapped and begins the cycle of mold growth.


Excessive use of humidifiers can cause the same issue as improper venting. When using humidifiers in bedrooms, the warm air can build up in the ceiling and soak through to the attic space. Although the bedroom ceiling may eventually dry off, he attic moisture is unlikely to do so as easily.

Roof Leaks or Ice Dams

Be sure to inspect your roof after any big rainstorm or during the winter months when snow and ice can accumulate. Roof leaks are another one of the most common causes of mold in attics. Don’t forget to check around chimneys, skylights, attic windows, and flashings as they are prime spots for potential moisture to seep through. Address any of these problem areas properly before it’s too late!

Summary of Most Common Causes of Mold in Attics

No one wants to discover mold growing anywhere in their home – let alone in places they rarely visit. Now that you are aware of some of the common causes of mold in attics, you can launch a preemptive protection plan to avoid this pesky problem.