Window Terminology

III. Other Terms

Grills The common industry term for the muntins bars that divide the glass into smaller panes.
RMB Removeable Muntin Bar – usually wood but occasionally plastic, held in place against the interior face of the glass by fasteners.
GBG Grills Between Glass: grills that are permanently installed in the air space separating two sheets of glass in an insulated glass unit.
SDL Simulated Divided Light: Grills that are permanently overlayed over the glass surface – usually on both the interior and the exterior.
ADL Authentic Divided Light: Windows that are composed of individual panes of glass separated by muntins. Usually single-glazed.


Brick Mould/Exterior Casing Usually called the “brick mould”, sometimes called the “exterior casing”. This is the approximately 1.25” x 2” (30mm x 50mm) piece of exterior trim attached to the window frame that “trims" the space between the window and the brick or the edge of the siding.
Step Brick Mould A brick mould with “steps”, where each step juts out progressively further than the previous step.
Groove Brick Mould A brick mould that is flat but has a groove(s) carved into it.
Flat Casing A brick mould that is smooth and flat with no steps or grooves.