True Divided Lites vs.Simulated Divided Lites
When choosing steel doors or windows, one detail worth considering is how the glass is divided.
True Divided Lites (TDL) and Simulated Divided Lites (SDL) can look similar, but they're built differently. The choice affects the width of the glazing bars, overall appearance, and cost.
How the glass is divided
What Are True Divided Lites (TDL)?
True Divided Lites use individual glass panes separated by structural steel bars, also called muntins.
Each pane is installed separately within the frame, creating actual divisions in the glass.
TDL is commonly used in traditional French doors, heritage-style windows, and projects where authentic divided-glass construction is preferred.
Because each pane requires its own framing, TDL generally has wider dividers and costs more to fabricate.
What Are Simulated Divided Lites (SDL)?
Simulated Divided Lites use a larger glass unit with decorative bars applied to the glass surface.
The bars create the appearance of separate panes without physically dividing the glass.
SDL allows for slimmer glazing bars in many configurations and is often more cost-effective.
It's a practical option for steel doors and windows where narrow sightlines are important.
SDL vs. TDL: Key Differences
| SDL | TDL | |
|---|---|---|
| Glass | Continuous glass unit | Individual panes |
| Dividers | Applied to glass | Structural steel bars |
| Sightlines | Typically slimmer | Generally wider |
| Cost | Generally lower | Generally higher |
| Cleaning | Easier to clean | More edges to clean |
| Appearance | Divided-glass look | Authentic divided glass |
Which Should You Choose?
If you want very narrow glazing bars, SDL is often the better choice. It provides the divided-glass appearance without the wider structural profiles required for TDL.
If authentic divided-glass construction is important to the project, TDL may be more suitable.
What About European Steel Systems?
BlackFramed works with European steel systems from Ottostumm, Secco Sistemi, Forster, and Welser.
Not every system supports the same divider dimensions or glazing configurations.
For example, certain Ottostumm W40 configurations require wider bars for true divided lites. If your design calls for narrow dividers, SDL may be the more practical option.
Arched doors and other custom configurations may also have restrictions depending on the selected system.
Need Help Choosing?
Send us your drawings, preferred glass pattern, or reference photos. We can help determine which option works with your selected steel system.