Mullions vs. Muntins: The Differences

When you’re having a home remodeling project done, chances are you’re having your windows replaced as well. And when you’re replacing your windows, chances are you’ve heard the terms “mullions” and “muntins” thrown around. For those who are unaware, mullions and muntins are both parts of the window that support it. But what exactly sets them apart from one another?

In this article, Renewal by Andersen® of Sacramento reveals the differences between window mullions and muntins.



While muntins are often associated with replacement windows, these actually refer to any vertical divider that can be seen in windows, furniture, doors and even wood panels. Oftentimes, muntins were built because they were structurally necessary as the outer walls of buildings could not carry the weight of the large windows placed on the walls. With these muntins, the windows’ weight can be transmitted vertically.


While they both act as supporting devices, window mullions are still different from muntins. A mullion is usually a vertical bar between the panes of glass in a window and was a necessary window component as it was once impossible to manufacture large sheets of glass. Thanks to the window mullions, giant expanses of windows were achieved as they held the small panes of glass together.

Mullions and Muntins Nowadays

A modern day home may still have mullions or muntins on their windows but nowadays, they’re usually called by a universal term: grille. Their functionality was also changed from the past 100 years as these grilles usually no longer serve a structural capacity but are now only there for aesthetic appeal.

Planning to install new doors or windows in your home soon? Simply turn to Renewal by Andersen of Sacramento. When it comes to window replacement and installation projects, we are the area’s number one service provider and we won’t let you down! Give us a call at (916) 779-5800 or fill out our contact form to schedule a FREE consultation. We serve homeowners in Sacramento, CA, and other nearby areas.