Window Mullions vs. Window Muntins

Have you ever heard of mullions and muntins? Well, these are terms that are used interchangeably in window construction. They’re architectural jargon that every homeowner should know.

The difference between mullions and window muntins is that mullions are structural members in a window frame, while window muntins are simply vertical dividers used to separate glass panes. In this article, we’ll differentiate the two as well as cover a few of their uses. Keep reading!

Definitions and Meaning

The definition of muntins dates back to an English architecture glossary from 1850. The English joiners applied this term to both outside upright stiles and middle vertical bars of the frame.

According to the Oxford English Dictionary, mullions are vertical bars between the glazing bars in a window, screen, or panel. Mullions represent heavy, vertical pieces between adjoining window units that join window frames with one another.

Fixed, operable windows can be performed using the muntin bars. They can also help strengthen a window structure and assist in transferring load from the glazing points to the wall by changing its shape and preventing any cracks that may occur.

What are Window Mullions?

Mullions have many more functions than just separating glass panes. You can use them to create an elegant focal point or support large windows with multiple panels. Before the Victorian Age and the advent of inexpensive plate glass, the manufacture of large sheets of glass was very rare.

What are Window Mullions?
Image credit:

Even though there were more significant pieces of glass, they were used to create mirrors which were expensive at times. Therefore, they had to create large windows with supportive mullions to hold small glass panes together. And since glass joints were also weak in case of large openings, they added some depth to distribute the wind load evenly.

Additionally, mullion bars often contain decorative elements such as crown molding or other carvings. These elements make them attractive when paired with stained glass inserts or clear glazing options like our translucent white vinyl. Window mullion styles have since evolved and are now used with large divided windows and doors.

What are Window Muntins?

Window muntins muntin refers to the narrow strips of wood, metal, or most commonly plastic that divide a window into smaller panes that let in light. They are typically located within the window frame and hold the window panes intact through cross members attached with screws to keep them together.

What are Window Muntins?
Image credit:

They are any vertical divider used in windows, doors, and furniture, especially in older windows like the traditional sash windows. They are often used on large windows or French doors and can be made of wood, metal, or plastic. However, not all windows with individual panes have a wooden piece that divides them. Instead, they have simulated divided lites. 

These lites resemble muntins but are encased within window panes. You can also add them on both the interior and exterior of the glass and over the outer surface of the front window panes to get an excellent divided look. Although muntins are associated with windows, they can mean any vertical divider, be it windows, wood panels, furniture, and doors.

These are thinner and have a custom design since they aren’t real. Some windows have no dividers, having only the glass panes that sit next to each other until they meet an obstruction or end of the wall. Muntins are not only used in windows. They can be added to doors to create individual lites. Muntins were also used in outer walls where early buildings didn’t fit for carrying large windows.

What is the Difference between Mullions and Muntins?

Both of these terms are used in window and door construction, and they describe dividing and joining glass and frames. The main difference between window mullions vs window muntins is that mullions divide openings while muntins divide glasses. Muntins are sash bars made of wooden and metal strips that separate and hold panes of glass in the windows. They divide single-hung window sashes or casements into a grid system of all small window panes.

Additionally, mullions divide the window or door opening into smaller blocks, while muntins are the vertical pieces of wood separating glass panes. Mullions also allow dissimilar items such as glass and vinyl to be joined together while the muntins separate them. When manufacturers refer to mullions, they think of both vertical and horizontal bars, but the correct name of the horizontal mullions is the transom. 

lternative to Muntin and Mullion Terminology

Window mullions and muntins are often confused because they can be technically identical. Their difference is subtle but important. The phrase mullion glass refers to a window frame with mullions, which means there are divisions between each window pane instead of one large piece of glass. 

The term mullion itself is interchangeable with the term window muntin because the two words refer to the same thing. There are several other types of window dividers that can be used in place of mullions and muntins, including grids, bars, and grills. These can usually hold more than one pane of glass or mirror each, which is why they are often found in large windows.

Styling Muntin vs. Mullion

When you want to apply muntins and mullions in your home, you need to consider the shape, color, and material. Different colors and materials can give your home a completely different look, especially when it comes to the materials used in each. 

To achieve better results, make sure your muntin contrasts well with your home’s exterior paint color. When it comes to mullion, make sure it matches the style of the house as a whole.

Mullions can be made from wood or metal, and they can have a more rustic look which would work well with your country house design. When choosing between muntin vs. mullion, make sure you choose one that will meet both your needs and your taste when it comes to home decor

FAQs on Window Mullions vs. Window Muntins

Why do windows have mullions?

Mullions are vertical elements that divide two or more units of windows. Their main purpose is to provide rigid support to the glazing of the window. You can also use them as decorations.

re mullions and muntins updated?

Yes, mullions and muntins are used as an updating feature for either new or old houses. They can be made to look modern, but they can also have a more traditional look that adds detail to homes’ exterior design.

Final Thought on Window Mullions And Window Muntins

Both window mullions and window muntins can add much to the design of your home. The choice is yours regarding which one you want to update your exterior and add detail to the windows. Adding these elements into your home is a great way to show your personality through your home and merge beauty with function.


The post Window Mullions vs. Window Muntins appeared first on Kitchen Infinity.

Did you miss our previous article…

Victoria Grant