Mullions vs. Muntins: What’s the Difference?

People often use the terms “mullion” and “muntin” interchangeably when talking about windows, but they are actually two different window components. Knowing the difference can be helpful when discussing your replacement window plans with your contractor. In today’s post, Renewal by Andersen® of Central Pennsylvania shares an overview on the difference between the two.

Mullions

In addition to the alliteration in their names, mullions and muntins are both components that provide vertical support. This is where their similarities end. A mullion is a structural component that separates two window units vertically, sometimes horizontally. Instead of creating individual openings for windows, home builders create a large opening on the wall. Multiple windows in the same opening are separated by mullions, which can be removed at a later time if you choose to combine the smaller windows into one large window.

Muntins

Muntins are also known as grilles. These are narrow strips of wood, composite, or vinyl that divide window glass into smaller panes. Traditional windows have muntins that hold small pieces of glass, or “lights”. However, today’s replacement windows feature muntins that are fully decorative, and can be removed to allow easy cleaning.

Renewal by Andersen® offers custom muntin designs in three configurations:

Full divided light grilles – These grilles are ideal if you want to replicate traditional muntins without sacrificing features such as energy efficiency. Our full divided light grilles feature exterior grilles made of Fibrex® material, aluminum spacers between the glass frames, and removable or permanent interior grilles.

Between-the-Glass— These are aluminum grilles are permanently installed between the panes, which provides structural support while making it easy to clean the glass surfaces.

Interior Wood Grilles — These are decorative muntins made of hardwood, which snap onto clips located on the interior sash. They can be removed for easy cleaning.

Renewal by Andersen® of Central Pennsylvania is your leading provider of popular replacement window styles, including casement windows. Give us a call at (717) 929-8610. You can also fill out our contact form to schedule an appointment. We serve York, PA, and the surrounding communities.