WarmCore casement windows are available in a ‘flush sash’ option for the ultimate in clean, modern aesthetics. Using a stepped outerframe, the sash - the opening part of the window - sits on the same plane as the rest of the window, creating a pure, cutting-edge look to this high performance window system. In addition where two flush sashes meet, WarmCore uses a feature mullion - which echoes the flush sash feature, creating a precise bead line in-between the two windows.