A cool roof covering for forming the outermost layer of a bituminous roof coating is provided, this cool roof covering comprising multiple heat-reflecting cap-sheets arranged in an adjacent, overlapping edge fashion and a heat-reflecting cap-sheet adhesive applied to overlapping portions of the cap-sheets for securing these cap-sheets to one another. The heat-reflecting cap-sheets exhibit a solar reflectance of at least 60% and a thermal emittance of at least 65. The heat-reflecting cap-sheet adhesive comprises a storage-stable, VOC-compliant mixture containing at least 10 wt. % of one or more weather-resistant organic resins dissolved in an organic solvent, the adhesive having a viscosity of 15,000 cps or less at 77.degree. F. (25.degree. C.) and exhibiting a lap shear strength of at least about 17 lbf/in when applied to a substrate and dried.