Attic mold shows up as dark staining on the underside of the roof sheathing. Remediation removes it — but if you don’t fix what caused it, it comes right back.
The three usual causes
- Poor ventilation. Without enough soffit and ridge venting, warm moist air condenses on the cold roof deck in winter and feeds mold.
- A roof leak. Even a small one keeps the sheathing damp.
- A bath or dryer fan venting into the attic instead of outside — pumping humid air right where it does the most harm.
Fix the cause, then remediate
Re-route fans outside, add or clear vents, and repair leaks. Skip this and you’ll pay to remediate the same attic again.
What it costs
Attic jobs run a bit higher per square foot because of the cramped, hot working conditions and frequent encapsulation. Get a ballpark with the attic mold removal cost calculator, and if the growth looks dark and slimy, check the signs of black mold first.