Change the Look of Your House by Adding Window Muntins

June 22, 2014

Muntin’s vs. Mullion’s

So what is a Window Muntin? First we better set the record straight as there seems to be some confusion as to the difference between a Window Muntin and a Mullion. A window Muntin is the decorative slats that break up a window into smaller panes. These are also known today as window grills or grids. In days-gone-by, Muntins actually served a structural purpose by holding small panes of glass together in a larger window opening. Today however; a Muntin is primarily a decorative accessory.

A mullion is a heavy structural member that separates and supports two larger windows. A mullion is typically found between two double hung windows that are installed side by side. For instance, a smaller room such as a bathroom or small bedroom may have a single window that is 26” wide x 48” tall. A larger living space may have two of these windows adjacent to one another to create a 52” wide x 48” tall window. In the latter case, the structural member between the two double hung windows is called a Mullion.

Change the Look of Your Home

Adding Window Muntins to your existing double hung windows can change the entire look of your home, especially when viewed from the street. Large, undivided windows can appear cold and uninviting. Adding Muntins to your windows will make your home look more inviting and project a cozy feel. This is particularly true if the Architectural Style of your home is a New England Cottage or Old English Manor. Muntins have also become very popular and common in upscale communities throughout the country.

Take quick drive through Plainfield, Naperville, Coal City, Braidwood, Wilmington, and Joliet, and you will see hundreds of homes that have had Muntins or Grids added to their windows.

DIY Muntins

For the Handyman, installing Muntins or window grids on your own can be a fairly simple task. Some window manufacturers offer conversion kits that simply snap into place. Take a measurement of all of your existing windows and develop a comprehensive list of all of the windows in your home that you can submit to the manufacturer or local dealer.

If standard Muntins are not available for your brand of windows you can build your own. Purchase random lengths of wooden slats from your local hardware store. These can be simple flat 1” x 3/8” strips, or a more complex profile for a more eloquent look.

Measure the window and divide the dimensions equally. For instance; for a 30” wide x 24” tall pane of glass, you would create a grid of 3 wide x 2 high. So each individual segment within the grid becomes 10” wide x 12” tall. Your grid will tend to look better if the height of the individual segments is greater than the width, although this is not always feasible.

Apply masking tape to the existing window frame so you can mark the centerline where the new slats will be installed. Measure the vertical height of the existing window and cut the slats to suit. Mark the center-line of where the horizontal slats will intersect the vertical slats and cut a notch that is equal to the width of the slat and half the thickness. Repeat this step for the horizontal slats.

The best way to attach your new Window Muntin Grid is with clear hook and loop fasteners. This will make it easy to remove the slats when cleaning your windows. You can also use a a commercially available retaining clip.

Finish-up by priming and painting your project using high-quality paint!

Hire a Pro

If this project seems a little overwhelming, hire a pro! For professional service, contact One Source Renovation, LLC at for a FREE Quote. (815)-634-8922