Divided lite window patterns are an essential element for many architectural design styles, and for centuries have added a defining characteristic to a wide range of styles from elegant, old-world to arts and crafts, and even the most minimalist, modern designs. When your project includes window divisions, there are two options to help you achieve the effect: true divided lite and simulated divided lite windows. Which is best for your design vision?

True Divided Lite Windows

At the beginning of the glass production industry, glass makers (or glaziers) were only able to produce very small glass panes. These glaziers developed a method of attaching multiple, smaller panes of glass together with muntins and the True Divided Lite (TDL) windows were born.

True divided lite (sometimes referred to as divided light) windows consist of multiple panes of glass separated by muntins.

This traditional approach to achieving a divided window is still used today. Here are the benefits to choosing this time-honored method for your design:

• Strength: Structurally, true divided lite muntins and bars strengthen and stabilize the window sash, particularly the extra-tall or extra-wide sash so common in architecture today.
• Lighter Weight: Smaller, individual panes can allow for thinner, and therefore less heavy, glass. This can be beneficial for extra large swing and glass sliding doors, for example.
• Appearance: TDL windows can help hide spacer bars, and in steel windows and doors the lock box is generally etched into the glass, which enhances the overall beauty.
• Maintenance: If a single pane of glass is broken, it can be much easier and less costly to repair later compared to a simulated divided lite window.

While there are many benefits to choosing a true division for your windows and doors, there is a consideration, as well. The extra metal from the muntins and bars used in a TDL window can increase the thermal conduction and U-Factor result of the window.

Simulated Divided Lite Windows

As innovations in glass production and stronger frame materials made larger panes a possibility, Simulated Divided Lite (SDL) windows brought another alternative for those seeking the historic aesthetic of true divided windows in a space. While they both offer a similar appearance, SDL windows are crafted quite differently compared to their true divide counterparts.

Simulated divided lite (sometimes referred to as divided light) windows are made from a single, large pane of glass with a surface grid welded over the exterior.

Simulated divided lite windows may look similar to a true divided window, but come with their own benefits and merits, such as:

• Thermal Performance: the single pane of glass offers improved NFRC and U-factor ratings for better performance values compared to multiple, joined panes.
• Sightlines: SDL windows allow for a narrower width of muntins and bars. Widths less than 1” can often be achieved with an SDL.
• Appearance: the interior beauty ring is also welded with a matching grid pattern, which gives the appearance of a true divided lite window.

The higher thermal performance of a simulated divided lite product does come with a few considerations, as well. These “faux” divides may lack an architectural authenticity and may not be preferred for restorations or projects where an authentic window style is preferred. And the SDL muntins and bars are shallower and do not share the same depth as the profiles in the sash.

Both types of divided lite window and doors can help bring your design to life. Whether you want the strength and authenticity of a true divide, or the improved thermal performance and narrow muntins of a simulated divide, each product will bring its own unique benefits to a design. And the end result will be a stunning window pattern that makes the window as breathtaking as the view beyond.

Visit our Divided Lites features page to learn more.