Transom Grids

Decorative Window and Transom Grids

transom1Transoms are a type of window located above a door, window, or other glazing materials; the most common type are found above a door.  Sizes of transoms mimic the size of the door. On a 36” wide door, you will usually find a 36” transom that is 24” in height.  A rule of thumb for a standard proportional transom height is to use 1/3 of the door’s height. A large curtain wall can utilize a transom and will follow the bay divisions of the wall. At times, the transom can be cut to an arch shape for functional or aesthetic purposes.

A transom is typically fixed glass or operates like a hopper window. A fixed transom has no operable parts. Its main purpose is to let light into a room and provide architectural appeal.  An operable transom is hinged at the bottom of the window. The transom will then open into a room, preventing rain, wind, or snow from entering room during inclement weather.

Traditional transoms are often adorned with gridwork, especially in traditional applications. Decorative items are added when the building is in a historic district or needs curb appeal . One of the most popular additions to a transom is a Palladian arch. In this case, a half round transom is utilized, and the exact radius is determined by the client.

Another decorative grid option is to include leaded grids on the transoms. This is a very historical style. Old homes and buildings used leaded grids before any of the vinyl or aluminum grids were invented. Stained glass windows utilized leaded gridding, and this is where leaded grids became popular.

A third option for the transoms is to etch the glass. There are different methods depending on desired outcome. Acid etching is used to create a texture on the glass. This process will create a e-dimensional texture, such as grass or rain drops. Another option is to sandblast the glass to create flat designs. Standard design offerings for sand blasting are shown below. The third option is v-groove, where the glass is chiseled.  This process is similar to carving wood, because an actual indentation is present on the glass.

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Please Note: When internal dividers are used in an insulating glass unit, such as grilles, muntin bars, or simulated divided lites, there is the potential that dividers will contact the airspace glass surfaces (surface #2 and #3) of the insulating glass unit.

This is caused by: Cold temperature conditions, high barometric pressure conditions, the Insulated glass unites or windows are being shipped to an altitude below the insulated glass fabrication altitude, fabrication of insulating glass units where the insulated glass unit airspace thickness tolerance is at a lower limit, buffeting wind conditions, or fabrication of tempered insulting glass units where the tempered glass has a bow in the glass

When the metal dividers contact the airspace glass surfaces, there is the potential for having condensation on the room side (#4 glass surface) immediately behind the metal divider. This is because the insulating glass unit has lost its insulating value where the divider contacts the glass surfaces, causing the indoor glass surface to be colder. Therefore, there is more opportunity to have room side condensation with internal grilles than with standard insulating glass products that do not contain these grilles.

The information above was provided by Cardinal IG – to read Cardinal’s entire technical bulletin on this matter, please click here.

Additional Decorative Elements