Carefully inspect the seals around all roof openings. Check gutters and downspouts for any blockage. And look to see if any nails are backing out. The fasteners in metal roofs should also be regularly inspected. Jones says if the rubber grommet screws in a metal roof start to crack, chip, and disintegrate, they will have to be replaced.
Inspections can reveal some unexpected conditions.
Al Kessel, owner of a roofing company in Charlotte, Virginia, says his workers were looking around for the cause of a leak in a metal roof that was only ten years old when they discovered an arrow stuck in the roof. Kids had been shooting hunting arrows into the air. One of the arrows managed to penetrate the roof. Another time workers found a five-foot tree growing out of a gutter. Other times they found bullet slugs.