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Posted on Dec 18, 2018 by Sam Heer

Mullions, Muntins and How They Enhance Your Windows

You’ve probably heard about mullions and muntins when people talk about replacement windows. These two features are similar but they are also quite different from each other. More importantly, they can enhance your windows and your home’s exterior. Here’s a brief discussion on these two, straight from our window experts at Renewal by Andersen® of Central Illinois.


Mullions are vertical bars that go from the top edge of the frame to the bottom, dividing glass panes in the process. Mullions are usually made of the same material as the main edge of the frames. A window with mullions would have several vertical, rectangular glass panes instead of having one continuous pane.


Muntins are similar to mullions except they divide the window horizontally. A bay window will feature muntins to provide structural support to larger glass panes. Muntins are often seen with mullions (forming smaller rectangular panels), but unlike their vertical counterparts, they are rarely seen without them.

Better With Detail

One of the main purposes of mullions and muntins is to provide a layer of detail to the home’s exterior. Instead of a single continuous glass pane, the lines formed by both mullions and muntins make the home look more dynamic or intricate. This is why classic window designs favor windows with mullions and muntins and smaller glass panels over larger panels.

Stronger With Support

Mullions and muntins are also used for more functional purposes. As with the example made earlier with the bay window, larger window types have a better chance of resisting damage with both features supporting smaller individual panels. This also means damaged glass panels on double-hung windows can easily be replaced, since smaller glass panels are simpler to replace.

Learn more about mullions and muntins with help from our experts. Renewal by Andersen of Central Illinois is the leading window company in Champaign, Bloomington and Galesburg, IL. You can call us at (866) 693-6707 or fill out this contact form to request an estimate.


"I would recommend RBA of Central Illinois for QUALITY windows and doors. Compared to our old cheap, thin vinyl windows, Andersen blows them away. You can easily tell by how well the sliding doors fit and close, and how heavy duty they are. We also cannot hear the wind rushing through the house in inclement weather anymore! And the black window frames we went with are amazing to look at. Aaron, Al, Darrell, and Cory all were professional and went all out to finish the job, given the weather they had to deal with. I would definitely recommend. They were also on top of communicating with me given the weather delays, and what I could expect for them coming out. Five stars!"

Eric L.

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