Abstract: The present invention is directed to a diverter and to a method that prevents rainwater from seeping behind siding or under roofing material, yet at the same time does not allow the buildup of debris creating a back up of water or allow the formation of ice dams to create a back up of water. In one form the present invention is installed to a vertical wall at a juncture between the vertical wall and an edge of a sloped roof to prevent water flowing along a roof-wall juncture from seeping behind siding located on the vertical wall and shingles located on the sloped roof. The invention comprises a back wall, a top wall, a bottom wall, a first side wall, and a second side wall in the form of an open sided box. The open side extends outwardly from the vertical wall to serve as an exit, with the top wall having at least one access opening.