Unfortunately, roofs are not maintenance free and should be blown off and inspected at least once a year. On homes with valleys, where two roof planes meet at a downward sloping angle, debris may become impacted which could lead to water damage. Tile roofs may require more frequent maintenance as leaves and debris can get stuck underneath the tiles. Routine maintenance can be anything from keeping drains and gutters clean to cutting back tree branches. Some roofs that have shading may show signs of algae which should be removed by a roofing professional not a pressure washing company.