Window grid patterns are one of the simplest ways to give replacement windows the right architectural character. The grid you choose can make a new window look true to a Colonial, Craftsman, or Prairie-style home, or keep a modern home clean and uncluttered. If you’re shopping for custom replacement windows, here’s what to know about grid patterns and how they’re made.
Muntins, Mullions, and Grilles: Getting the Terms Right
These terms are often mixed up, so it helps to start with the basics:
- Muntins are the thin bars that divide a single sash into smaller panes of glass.
- Mullions are the heavier vertical or horizontal members that join two separate window units together.
- Grilles is the general term most manufacturers use for decorative bars that create a divided-glass look on modern windows.
The National Park Service guide to historic windows illustrates these parts, including rails, stiles, and muntins, on a traditional wood double-hung window.
How Window Grids Are Made
True Divided Lites
True divided lites use separate pieces of glass held in place by muntins, the way windows were built historically. They offer the most authentic look but are less common today because many small insulated panes cost more and create more edges for heat to pass through.
Simulated Divided Lites
Simulated divided lites use bars permanently attached to both the inside and outside of a single insulated glass unit, often with a spacer bar between the panes. From a few feet away, they look very close to true divided lites while keeping the efficiency of a single glass unit.
Grilles Between the Glass
Grilles between the glass are sealed inside the insulated unit. The glass surfaces stay flat, so cleaning is easy, and the grilles never collect dust. The trade-off is a flatter, less dimensional look.
Removable Interior Grilles
Some windows offer grilles that snap onto the interior side and can be removed for cleaning. They’re a budget-friendly option, but they’re more noticeable as an add-on.
Popular Window Grid Patterns
Colonial
The Colonial pattern divides the sash into a regular rectangular grid, such as six-over-six or nine-over-nine on classic double-hung windows. It’s a natural fit for Colonial, Cape Cod, and many traditional homes.
Craftsman
Craftsman windows typically have grids only in the upper sash, often with vertical bars dividing it into three or four panes, over a single undivided lower pane. The style emphasizes clean lines and works well on bungalows and Craftsman-inspired homes.
Prairie
The Prairie pattern places narrow panes around the edges of the sash, leaving a large open pane in the center. It frames the view while keeping the window mostly clear.
Diamond
Diamond grids create a crisscross pattern for a Tudor or cottage look. They’re usually best as an accent rather than on every window.
Grids and Energy Efficiency
Grilles between the glass and simulated divided lites have little effect on a window’s insulating performance, since the window still uses a single insulated glass unit. If efficiency is a priority, choose energy-efficient insulated windows first, then add the grid style you like.
Choosing Window Grid Patterns for Your Home
Look at your home’s architecture, the existing windows on your street, and any HOA or historic district guidelines. It’s also wise to keep window grid patterns consistent across the front of the house, even if you choose simpler grids or none at all on the back.
Want help choosing the right grid style? Call Murray Window Replacement at (385) 786-6447 or request a window replacement estimate to see your options.