Deteriorated or incorrectly installed flashing at roof penetrations such as plumbing vents, chimneys, and skylights can allow rainwater to enter through the roofing that can damage the roof structure and interior finishes. Visible water stains are usually the first indication water has leaked through the roof. Water will travel through the path of least resistance and may leave a stain far from where it first penetrated. Homeowners can inspect for water intrusion at roof penetrations by carefully looking for signs of leakage in the attic, water stains on the roof sheathing or even walls below, wet insulation, and deterioration of roof coverings and roof deck. The flow of water on the roof should be observed from inside if possible and outside while it’s raining and afterwards.