True Divided Lites (TDL) vs. Simulated Divided Lites (SDL): Which should you choose?

If you’re shopping for windows and glass doors, you may have heard of the terms “true divided lites” and “simulated divided lites”, but people seldom explain what those terms mean.

What are the differences between TDL and SDL?

black steel window profile true divided lite and simulated divided lite

The difference between authentic and simulated divided lites is often overlooked, but to understand both terms properly, first, we need to explain what a lite and a mullion are.

A lite, sometimes spelled “light”, refers to each separately framed piece of glass on a window or door. On the other hand, a mullion is a line that forms a division in a window or door; this division can either be real or simulated.

So when someone says that a window’s lites are truly divided (TDL), they mean that the glass on the window isn’t a single piece, but multiple pieces separated by mullions that go through the glass.

When someone says that a window’s lites are simulated (SDL), then they mean the glass is a large, single piece with mullions placed on top of the glass, but they don’t cut through it.

What are the benefits of each lite style?


True Divided Lites:

Simulated Divided Lites:

Which style should I choose?

The popular look of many smaller individual panes of glass in a window or door is a classic in historical neighborhoods, modern, or even minimalist homes. In certain areas in the US, some homes have to comply with regulations to keep authentic divided lites when replacing windows or doors, some opt for this style for aesthetics and the high-end feel they have, but for some other homes, simulated divided lites can do the job just fine.

Rhino fabricates True Divided Lites that provide the original look and feel of individual panes, adding that extra touch of luxury that any home can enjoy.

Contact us now for more information on our extensive line of TDL products, which include pivot doors, folding doors, sliding and classic swing doors for projects in Los Angeles, San Jose, San Diego and across the US and Canada.


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