A Brief Comparison Between Window Mullions and Muntins

If you’ve ever read about window construction, you’ve probably come across the terms muntins and mullions. Both words are used to describe the joining and dividing of window glass and frames, but they actually have some slight differences. 

What Is a Mullion?

This refers to the vertical bar between the window openings. In the past, mullions had to be added to large window openings so that the installed unit wasn’t too large. Mullions divide this large opening into smaller blocks, which are then used to fit two or more fixed frame windows. Because mullions are added at the intersections of these windows, they allow several units to be joined to one another.

What Is a Muntin?

Do you see that vertical and horizontal piece of material separating the panes of glass in your large windows? That’s called the muntin. Before inexpensive plate glass was invented, it was virtually impossible – not to mention expensive – to manufacture or transport large sheets of glass without breaking. To fill a large window frame with glass, smaller panes have to be joined together using muntins. Unlike mullions which divide window openings, muntins work to divide the window glass. What’s more, they helped keep the window glass intact: glass joints in large window frames were typically weak, but muntins reinforce them to better resist wind load. 

Because window manufacturing has had many advancements, mullions and muntins are actually no longer necessary, except for aesthetics. In fact, these terms are now lumped together into a universal term: grille. When you turn to Renewal by Andersen® of Houston for your window replacement, you can customize your new units with your choice of grille pattern. We offer lovely and classic Farmhouse, Colonial, Prairie and Modified Prairie grille options, which can help add to the vintage look of your home.

When in need of high-quality replacement windows, including picture windows, look no further than Renewal by Andersen of Houston. We’ll make sure your home remains lovely, comfortable and efficient with our exceptional products and services. We serve Tomball, Houston and Sugar Land, TX, and the surrounding areas. Call us today at (281) 547-6177, or fill out this contact form to schedule your consultation.