How to Add a Window Grid by Using a Kit

Adding window grids to your existing windows is a quick, inexpensive, and easy way to update your home’s look without having to install new windows. You can modify any type of window with grids, or mullions, whether it’s double-hung, sliding, or casement, and made out of metal, vinyl, or wood. The do-it-yourself grid kits usually have pieces made out of white polyvinyl chloride, or PVC, but you can paint them any color prior to installation.

Check out the easy steps below to get started transforming your windows.

Step 1 - Measure the Window

First, measure the vertical and horizontal dimensions of your window. Only measure the width and height of the single pane to be subdivided with window grids. Take into consideration any bevel that the window sash has in it that’s extending from the glass to the frame.

Step 2 - Determine the Window Subdivision

Most window grids are designed to create three squares width-wise and two vertically per sash. Your kit may come with exact specifications for sizing, or it might give you the freedom to customize your own pattern. Just ensure that you equally space your grids before installing.

Step 3 - Mark the Window

Once you’ve decided how to set up the grid, mark lightly with a pencil on the window frame where each strip of grid will be placed both horizontally and vertically. For the cross pieces that will affix to the glass, mark the intersection points lightly with an erasable pen. Use the level as a straightedge to ensure the grid will be plumb.

Step 4 - Cut the Grid Pieces

If you can customize the kit, cut the strips of PVC with a miter saw to length. If there is a bevel on the sash, you can cut the ends of the strip to correspond with the angle to create a seamless transition. If your kit is not customizable, follow the direction per the package instructions.

Warning: Use safety precautions when using a miter saw, including wearing proper safety gear like eye goggles and gloves.

Step 5 - Paint the Grid Pieces if Needed

If need be, paint the grid pieces to match the window color, preferably with spray paint. Let the pieces fully dry before installing. You may need to spray paint up to three coats to achieve your desired look.

Step 6 - Apply Tape

Apply the double-sided tape to the backside of the mullion pieces if they do not already come affixed. Start with the intersections on the glass, removing the paper backing and sticking the pieces to the window.

Line up each strip with the crossed lines, and affix them in the same way. Press down to ensure a good bond with the glass. Keep your level handy to maintain straightness.

Step 7 - Install Grid

Before installing the grid, make sure your measurements are correct. Although the pieces can be pulled off and redone, the double-sided tape will have to be replaced. Removing the tape could also strip the paint from the grid.

Done correctly, using a do-it-yourself window-grid kit will fool anyone into thinking you have an authentic, old-fashion grille, and your new look can even increase your property value.

Window Grid FAQ

Can you add window grids to existing windows?

It is very easy to add window grids to your existing windows. This can be accomplished by adding a trim to the windows.

The trim can be placed directly on the outside of the windows and it is a relatively simple DIY project.

How much does it cost to add grids to windows?

The cost of adding grids to windows varies, based on the size of the windows and the type of material the grids are made from. However, window grid kits are competitively priced, with kits ranging from under $20 to over $200.

What are fake muntins called?

Some window grids are designed to look like muntins, which help support and separate individual panes of glass. Fake muntins merely give the appearance of separating panes of glass, but they're actually placed on top of one single, large pane.

Faux muntins, or fake muntins, are called just that, or simply referred to as a window grid.

Do window grids add value?

Adding window grids will add value to your home. Every window that has a grid looks more decorative and therefore, more expensive, which helps add to the overall sale price you can ask for in an open market.

Are window grids out of style?

Window grids were once used as structural support before advancements in glassmaking made it possible to have large, perfectly smooth and uniformly thin pieces of glass. However, this is not an out-of-date or old-fashioned look.

Modern homes are still made with window grids, but now they are merely decorative and offer no structural value most of the time. Window grids are used in all sorts of home designs, from Revival and classic styles to ultra-modern creations.