Abstract: A system of temperature determination and control for molten bituminous material during construction of built-up roofs is provided wherein a heating temperature is preselected based upon a number of factors and is adjusted insofar as may be called for upon checking the temperature upon application to the roof deck. Factors considered in the predetermination include type of bituminous material, type of roofing material, and deck type and temperature; ambient temperature, cloud cover, and wind speed; and also opportunities for cooling of the bituminous material between temperature-controlled and deck locations, during application to the deck, and thereafter until application of an overlying layer of roofing material.