Double Glazing

Double glazed glass is the new black (or rather green…) due to energy-saving initiatives (LEED), government legislation, and genuine concern for the environment. With double glazing becoming the norm in structural glass walls, point supported glass hardware systems are part of this future. While we’re focused on double glazing due to its current popularity, we can also support triple glazed systems - if you’ve got a project that has triple glazing we’d love to talk to you about that too.

Double glazed glass is the new black (or rather green…) due to energy-saving initiatives (LEED), government legislation, and genuine concern for the environment. With double glazing becoming the norm in structural glass walls, point supported glass hardware systems are part of this future. While we’re focused on double glazing due to its current popularity, we can also support triple glazed systems - if you’ve got a project that has triple glazing we’d love to talk to you about that too.

HOW DOUBLE GLAZING WORKS
Sealed glass, double glazing, insulated glass units, SGUs are all different words for the same glass make-up of two panels of glass with a small air gap between. In this design, the air gap is generally about 12.7mm [1/2”] wide and the two pieces of glass are held apart with a spacer bar around the perimeter of the glass. Sealants around the perimeter of the edge of the glass prevent air and moisture from travelling into that air gap.

This is the basic system but can be made more energy efficient by adding metallic coatings on one or more surfaces of glass (generally Low-E), using argon instead of air in the gap between and using “warm edge” technology in the space bar to prevent heat loss. These improvements can be made both on traditional curtainwall systems as well as point-supported glazing systems.

HOW TO PREVENT HEAT LOSS WITH POINT SUPPORTED GLASS
Glass fabricators play a closer role when point-supported glass hardware is used with double glazing; we’re happy to work closely with your glass fabricator or suggest a fabricator we’ve worked with to manufacture the glass.

In our point-supported double glazed glass, the fabricator inserts portion of the glass bolt into the glass during fabrication and seals the bolt within the glass to provide a hermetic seal. This glass make-up undergoes IGMAC testing by the fabricator to ensure the seals are sound. The hardware also goes through our load testing to ensure that the glass fitting can carry the loads applied to the glass, ensuring you a structurally sound, non-leaking wall under one warranty.

OPTIONS FOR GLASS CONFIGURATION AND SUPPORT

COUNTERSUNK
When dealing with smaller pieces of glass (generally 1.2m by 2.5m) a glass bolt can be countersunk on the inner liteA term generally used in laminated or double glazing. Refers to the glass located on the interior of the building. with the outer liteTerm generally used in laminated or double-glazing. Refers to the glass located on the exterior of the building. being supported on the structural silicone. The glass make-up on the system is typically 12 to 15mm on the inner lite with a much thinner 6mm outer lite of glass.

As glass sizes increase, the deflectionThe distance that a structural member (such as glass) displaces when under load. This is an important factor to consider in design to manage the stress in the glass. of the glass also increases to a point past the recommended deflection of IGMAC (typically l/125). If this occurs, there’s a chance that with increased deflection, the outer lite might even bend enough to touch the inner lite. So while our countersunk solution works well with smaller pieces of glass; we recommend our “donut” solution for larger pieces. Please read on…

CONNECTION THROUGH BOTH PIECES OF GLASS
We’ve heard the demand for larger (and larger) pieces of glass and responded – a double glazed system with a bolt that is fixed through both pieces of glass is the solution for pieces of glass up to 2.4m by 2.4m. This system can either be finished with a tapered head bolt on the outer edge of the glass or have the face of the bolt countersunk into the outer lite. Some common glass make-up for this system are 10 to 12mm (equal for the inner and outer glass lites); an alternative arrangement is a 6mm inner lite with a 12mm to 16mm outer board of glass, all dependant on the final engineering. 

If a piece of glass is really on the large scale, we have an aluminum “donut” that can be added in the inside of the spacer. Acting in the same way as the spacer bar on the outer edge of the glass, the donut allows two pieces of glass to be the same thickness and optimize the load of both pieces of glass. In a project we recently completed in Seattle (Ashwood Commons), the glass was 10mm over 10mm in this system and the panels of glass were 2.6m by 2.4m.

EDGE SUPPORT
If you don’t want holes in the glass in your structural glass wall system, we can do that too. We’ve developed an edge supported system that could have the same glass make-ups and panel sizes as the above option for connecting through both pieces of glass. This “shelf bracket” would go through the glass joints between the glass panels at points along the edges (it’s not continuous); a pressure plate on the outside of glass holds the glass in place.

 

Products Used

StellaCustom

Double glazed glass is the new black (or rather green…) due to energy-saving initiatives (LEED), government legislation, and genuine concern for the environment. With double glazing becoming the norm in structural glass walls, point supported glass hardware systems are part of this future. While we’re focused on double glazing due to its current popularity, we can also support triple glazed systems - if you’ve got a project that has triple glazing we’d love to talk to you about that too.

HOW DOUBLE GLAZING WORKS
Sealed glass, double glazing, insulated glass units, SGUs are all different words for the same glass make-up of two panels of glass with a small air gap between. In this design, the air gap is generally about 12.7mm [1/2”] wide and the two pieces of glass are held apart with a spacer bar around the perimeter of the glass. Sealants around the perimeter of the edge of the glass prevent air and moisture from travelling into that air gap.

This is the basic system but can be made more energy efficient by adding metallic coatings on one or more surfaces of glass (generally Low-E), using argon instead of air in the gap between and using “warm edge” technology in the space bar to prevent heat loss. These improvements can be made both on traditional curtainwall systems as well as point-supported glazing systems.

HOW TO PREVENT HEAT LOSS WITH POINT SUPPORTED GLASS
Glass fabricators play a closer role when point-supported glass hardware is used with double glazing; we’re happy to work closely with your glass fabricator or suggest a fabricator we’ve worked with to manufacture the glass.

In our point-supported double glazed glass, the fabricator inserts portion of the glass bolt into the glass during fabrication and seals the bolt within the glass to provide a hermetic seal. This glass make-up undergoes IGMAC testing by the fabricator to ensure the seals are sound. The hardware also goes through our load testing to ensure that the glass fitting can carry the loads applied to the glass, ensuring you a structurally sound, non-leaking wall under one warranty.

OPTIONS FOR GLASS CONFIGURATION AND SUPPORT

COUNTERSUNK
When dealing with smaller pieces of glass (generally 1.2m by 2.5m) a glass bolt can be countersunk on the inner liteA term generally used in laminated or double glazing. Refers to the glass located on the interior of the building. with the outer liteTerm generally used in laminated or double-glazing. Refers to the glass located on the exterior of the building. being supported on the structural silicone. The glass make-up on the system is typically 12 to 15mm on the inner lite with a much thinner 6mm outer lite of glass.

As glass sizes increase, the deflectionThe distance that a structural member (such as glass) displaces when under load. This is an important factor to consider in design to manage the stress in the glass. of the glass also increases to a point past the recommended deflection of IGMAC (typically l/125). If this occurs, there’s a chance that with increased deflection, the outer lite might even bend enough to touch the inner lite. So while our countersunk solution works well with smaller pieces of glass; we recommend our “donut” solution for larger pieces. Please read on…

CONNECTION THROUGH BOTH PIECES OF GLASS
We’ve heard the demand for larger (and larger) pieces of glass and responded – a double glazed system with a bolt that is fixed through both pieces of glass is the solution for pieces of glass up to 2.4m by 2.4m. This system can either be finished with a tapered head bolt on the outer edge of the glass or have the face of the bolt countersunk into the outer lite. Some common glass make-up for this system are 10 to 12mm (equal for the inner and outer glass lites); an alternative arrangement is a 6mm inner lite with a 12mm to 16mm outer board of glass, all dependant on the final engineering. 

If a piece of glass is really on the large scale, we have an aluminum “donut” that can be added in the inside of the spacer. Acting in the same way as the spacer bar on the outer edge of the glass, the donut allows two pieces of glass to be the same thickness and optimize the load of both pieces of glass. In a project we recently completed in Seattle (Ashwood Commons), the glass was 10mm over 10mm in this system and the panels of glass were 2.6m by 2.4m.

EDGE SUPPORT
If you don’t want holes in the glass in your structural glass wall system, we can do that too. We’ve developed an edge supported system that could have the same glass make-ups and panel sizes as the above option for connecting through both pieces of glass. This “shelf bracket” would go through the glass joints between the glass panels at points along the edges (it’s not continuous); a pressure plate on the outside of glass holds the glass in place.