Abstract: An extruded plastic frame window sash in which the frame has a closed hollow body cross section with a recess extending into the hollow body from the outer periphery of the frame. The individual frame members are held together around a window pane by a tensioned band disposed within the recess and engaging each of the frame members. The tension band extends about the entire sash frame and is joined together at its end to maintain the tension in the band holding the frame together. The walls of the recess reinforce the frame members to prevent deflection induced by the tensioned band.