Integrated Window Takes Shape 
Manufacturers Realize Additional Benefits
by George Sivy and Jim Connery 

In most residential and light commercial windows, the glass is carried and held in place by the frame. For low design pressure (DP) windows, sealants are employed to seal out water and air. In higher DP units, and those designed for hurricane zones or bomb-blast resistance, stiffer sealants or adhesives are used not only as a seal, but also to provide a transfer path for wind loads or impact energy to the frame. However, whatever the DP rating, the basic structural work is done by the window’s strong frame or sash. 

Glass as a Strengthener
A new window design concept calls for the glass to actually integrate or bond into the window frame or sash as a structural element. The result is that the glass stiffens and strengthens the overall assembly. This new design offers several benefits to the window manufacturer, principal among which is a reduction of the structural needs from the frame or sash, thus allowing for thinner, lower profiles. Put simply, rather than the frame supporting the glass, the glass can now help support the frame. Realization of the concept has been made possible recently by the development and introduction of new bonding and sealing products. Other benefits from these products and new design will be discussed later.

The idea of increasing the structural integrity of a framing system by integrating the glass unit is not new: the principal idea comes from automotive glass bonding. Several decades ago, windshields, back lites and other fixed windows simply had to be see-through and seal against wind and water. Eventually designers realized that more aerodynamic designs could be made possible by using the glass as structural elements to increase the car body stiffness. With this approach, bulky, heavy pillars and other members could be reduced or sometimes eliminated.

Transferring this concept to residential window design seemed a natural progression, and the introduction of high strength, elastic adhesive systems now makes it possible. 

Now the window manufacturer is free to realize greater freedom of design while improving functionality and lowering manufacturing and raw material costs. Consider all of the advantages that might be realized: 

Cost Reduction
• Automated application, manufacturing and higher productivity;
• Small profiles due to greater rigidity;
• No need for steel reinforcement profiles with PVC up to certain window sizes; and 
• Low maintenance requirement because there is no need for readjustment at the manufacturer’s expense.

Improved Window Functionality
• Easy and precise opening and closing, readjustment never required; 
• Ten-15 percent more light incidence than with most conventional designs for brighter and more comfortable spaces;
• Better distribution of stresses than with wedges or mechanical securing; 
• Increased thermal insulation over some conventional designs;
• Additional security against intruders; and 
• Simple cleaning with smooth exterior glass surface.

New Design Options
• Differentiation due to slim frame aspects; 
• Large element sizes; and 
• Smooth exterior glass surface. 

This new design offers several benefits to the window manufacturer and hopefully now you have more information into the process to help you make an informed decision regarding whether or not to incorporate this new design into your window processes. 

George Sivy serves as application engineering manager for Sika Corp.’s appliance and component business unit, while Jim Connery serves as national account manager. Both are members of the Fenestration Manufacturers Association.

DWM
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