25 Roof Leak Warning Signs (With Photos) — When to Call a Roofer for Repair

Moment #19: Mold spots on roof sheathing

Dark spotting on roof sheathing often indicates persistent moisture or long-term leakage. Mold can spread quietly in attic spaces, especially where ventilation is limited. Even if the leak is small, repeated humidity can accelerate wood deterioration and create remediation costs. If you notice this, pair it with checks for wet insulation and airflow problems. Fixing the moisture source early is typically far more effective than cleaning alone.