Abstract: A tool for applying a cementitious mixture to a flat surface includes a head assembly for delivering the mixture to the flat surface. A housing is provided for containing a supply of the mixture and a control assembly is interposed between the housing and the head assembly for controlling the flow of the mixture from the housing to and through the head assembly. The control assembly is responsive to the housing being pressed against the flat surface to control the angle of the head assembly relative to the control assembly and to control the flow of the mixture through the head assembly.