Abstract: A system of fire protective sprinklers that fully cover and wet all areas of a structural roof threatened by a rapidly spreading fire, comprising a strategically placed array of roof mounted, long range water sprinkler heads, capable of fully covering the surface of the roof with a continual spray, keeping the roof wet to reduce its susceptibility to airborne embers that otherwise might ignite a fire; piping to carry water to the sprinkler heads; and a water source to provide water.