It's important to differentiate between a roof leak and condensation, as they have different causes and solutions:
Roof Leak: Occurs when water penetrates the roof covering (shingles, tiles, etc.) and enters the building.
Condensation: Forms when warm, moist air comes into contact with cold surfaces, like the underside of the roof deck, causing water droplets to form.
Roof leaks typically occur after rainfall or snowfall, and the water stains or drips often appear near roof penetrations, valleys, or damaged shingles. Condensation, however, can happen regardless of weather conditions, especially in poorly ventilated attics. If you suspect condensation, check for frost buildup or excessive moisture in the attic. Improving ventilation and insulation can help prevent condensation.