Muntin Vs Mullion: What’s the Difference?

This article explores the difference between muntins and mullions, two architectural elements in windows. Muntins are vertical and horizontal elements that divide window glass into a grid, primarily used for decorative purposes. In contrast, mullions are vertical shafts between windows that provide structural support. Historically, muntins were essential for holding together small glass pieces, while mullions, often made of stone, offered stability for windows or doors.

In modern construction, muntins serve a decorative role and can be placed on the exterior surface of the window glass or between glass panes. Modern mullions, now made of materials like fiberglass, steel, aluminum, wood, or uPVC, continue to provide support for adjacent window units. Both elements offer practical and aesthetic benefits, contributing to home security. Muntins enhance the visual appeal by creating a classic, divided-light look, while mullions ensure the structural integrity of large window assemblies. The combination of these elements adds to the overall architectural charm and functionality of windows in contemporary homes.