Today’s tip is to check the bathroom fan. Make sure it does not vent the into the attic. The excess humidity can cause mold to grow on the attic sheathing. The blackened insulation in the picture is a combination of moisture and dust. Mold does not grow on fiberglass insulation, but it can grow on the dust trapped in the insulation. Remember that mold only eats damp digestible materials. Mold will grow on the paper backing of the insulation.
Notice the moisture soaked blackened insulation: