dividedlight

Divided light refers to a window or door configuration in which the sash contains multiple individual panes of glass separated by narrow strips called muntins or glazing bars. In true divided light, the panes are separate pieces of glass held in place by the muntins, so the grid is real. Modern units may use simulated divided light (SDL), where a single pane of glass is paired with internal, exterior, or between-the-glass grilles to mimic the appearance of multiple panes without creating separate panes.

The pattern and arrangement of muntins determine the window’s look. Common configurations include vertical and horizontal grids forming grids such as six-over-six or four-light designs, as well as more decorative patterns like diamond or prairie styles. Materials for muntins and frames vary and can include wood, aluminum, vinyl, or composite systems. In true divided light, muntins may be integrated with the sash; in simulated versions, the muntin effect is achieved with decorative grids that do not divide the glass panes.

Divided light windows are characteristic of traditional architectural styles, including colonial, Georgian, and Victorian designs. They remain popular for restoration projects or for achieving a historic appearance in new construction. Energy performance depends on the glazing: true divided lights require multiple glass panes, which can reduce thermal efficiency unless high-performance glass is used; simulated divided lights can improve energy efficiency by using single-pane glazing with modern insulated units while preserving the visual motif. Regular maintenance is often needed for wooden muntins to prevent rot and weathering.