Abstract: A vertical glazing frame system for building curtain walls includes a sill assembly having a subsill shaped and dimensioned for direct attachment to a support structure and a sill shaped and dimensioned for receipt within the subsill for ease of installation and movement relative thereto. The system also includes a head assembly having a head receptor shaped and dimensioned for direct attachment to a support and a head shaped and dimensioned for receipt within the head receptor for movement relative thereto. The system further includes a jamb assembly and flashing plate extending over the sill assembly and the head assembly, the flashing plate including a first end coupled to the sill assembly and a second end covering the head assembly.