SDLs vs. GBGs

Okay, you’re probably wondering what we’re talking about …

The short answer: GBGS and SDLS are the decorative grilles on a window. 

The next question you might have “is what are grilles?” …look left- we did a quick sketch calling out the anatomy of a 2 over 2 double hung window.

Now you might be wondering why we’re talking about this at all… From an architecture standpoint we love windows.  They do a number of things for a structure –let in light, bring in fresh air, they also articulate the overall feel of a space.   Large windows with no grilles provide an unobstructed view allowing the most light into a space.   Windows with a lot of grilles harkens back to a more traditional, historical style that you will see driving down historic 6A on the cape.  

A historical cape cod house might have a 12 over 12 window pattern.  This means that there were 12 panes of glass in the upper sash and 12 panes in the lower sash.  A modern approach to this look that allows more light in and less cost is a 6 over 6 or 6 over 1 window which is commonly seen on the cape.

Historically, windows were a collection of smaller panes of glass that were joined together by muntin bars.  These muntin bars were integral to having a larger window unit; but they were also a weak point of the window from an energy standpoint.  The bars were made of wood or metal that acted as a thermal bridge from the interior of a structure to the outside.   As technology increased we found ways to produce larger pieces of glass without the need of this joinery and eventually we began producing double glazed and triple glazed windows that are extremely energy efficient.  So, from a functional perspective we don’t need the muntins (or grilles), but from a decorative standpoint we can have them in one of two ways.

Windows with GBGs, Grilles between the Glass

GBGs or grilles between the glass are just as their name describes --- grilles that are placed inside the double glazed window.  This gives the look of a traditional window from a distance, but when you are closer to the window you see that grilles are inside the glass.   These windows appear flatter in comparison to a window with SDLS. 

Windows with SDLs, Simulated Divided Lites

SDLS are an architect’s preferred detail for window grills.  SDLS or Simulated Divided Lites are grilles that are applied directly to the surface of the glass and provide the most authentic look for the window while still providing the energy efficiency of a modern double glazed window. These windows appear flatter in comparison to a window with SDLS.