4822 Southerland Road
Houston, TX 77092

(713) 353-5800 Tel.
(800) 238-3548 Toll Free
(713) 353-5333 Fax
(800) 825-9607 Toll Free Fax
E-mail: sales@craftsmanfab.com

Insulated Glass: Overview

To reduce heat gain or loss through glass, two or more lites are used to create dead air space that inhibits the transmission of heat and cold between the lites of glass. Craftsman Insulated glass is fabricated using a desiccant filled metal spacer between the lites, sealed with a dual seal system. This method of manufacture is widely acknowledged as the finest available in the market.

The Anatomy of Quality Insulated Glass

All insulated units are not created equally. Following is a brief primer of the major types of components utilized by major insulated glass manufacturers today.

• Spacers
• Corners
• Seals
• Handling and Assembly
• Tempered / Heat Strengthened Glass
• Gas Filled Units
• Low-E Glass
• Warm-Edge Technology
• Offset Units
• Breather Tubes

Spacers

The material and composition of spacers utilized in Insulated Glass varies greatly between manufacturers. Debate rages as to the relative advantages and disadvantages of each material. This discussion is generally centered on 2 major characteristics of the spacer; structural strength and thermal heat transfer through the spacer. While non-metallic spacers generally offer lower thermal heat transfer than metal spacers, structural strength and commercial quality is generally equated to metallic spacers. At Craftsman, we offer an ultra-low profile aluminum spacer that extends structural strength, while, due to its low profile, minimizes thermal transfer. Additionally, the insulated glass may be manufactured with a stainless steel spacer for even lower thermal transfer properties. (See Warm Edge Technology section below)

Corners

Seal failure at the corners of the spacer may constitute the single largest area for the potential unit failure. Simply stated, minimizing the number of joints or breaks in a spacer minimizes potential for failure in this area. Craftsman Insulated Glass is manufactured on a fully automated manufacturing line that bends the spacer out of a single length of material, thus eliminating all corner joints. This method of manufacture also enhances the structural integrity of the unit.

Seals

Ultimately, all debate concerning quality of Insulated Glass must come to a discussion of the material used to seal the individual lites of glass together. At Craftsman, all Insulated Glass Units are manufactured utilizing a “dual-seal” system to maximize seal life. A primary seal of Polyisobutylene (PIB) is first applied onto the edge of the spacer with a specially designed PIB extruder machine to insure a continuous uniform ribbon of material. This is critical to the ultimate performance of the seal. After the glass is pressed to each side of the spacer and sealed with the PIB, a secondary seal of Polysulfide is applied in the perimeter void of the unit. Commercial grade silicone may also be requested as a secondary seal.

Environmental factors and conditions have a definite influence on seal adhesion and ultimately, unit performance. Temperature extremes, water immersion, ultraviolet radiation, and stressing, alone or in combination with each other, can attack and degrade the seal. To best illustrate the superiority of a dual seal system, the following table outlines seal durability when tested at extremes. Various combinations were aged with P-1 Pre-Conditioning Chamber – 140degF, Water Spray, UV Radiation.

Handling and Assembly

All Craftsman Insulated Glass is manufactured on the most advanced manufacturing equipment available in the world today. Once quality components are chosen, the key to superior manufactured products is consistency and repeatability. Our fully automated manufacturing line insures that each and every Insulated Unit manufactured conforms to our high standards.

Tempered / Heat Strengthened Glass

Applications requiring additional strength properties and/or safety considerations may require one or both lites of the glass be tempered or heat strengthened. Craftsman manufactures both of these products in-house to industry leading standards. More information about these products can be found in the Tempered Glass area of this website.

Gas Filled Units

To supplement the insulating properties of the air space in an insulated unit, gas may be added. After years of testing it has been determined that the noble gases, Argon, Krypton and Xenon offer the most practical solution. Of these three Argon is the most plentiful and consequently the most economical. Why does gas filling work? Simply put, Argon is less conductive than air and therefore a better insulator. Argon gas is non-toxic and inert. It is clear, colorless and odorless, and poses no threat to people, animals or plants. Of course, argon can only be effective if the seal quality of the unit in which it is installed maintains it’s integrity and the gas does not leak out. Craftsman manufacturing techniques insure maximum durability.

Low-E Glass

By applying thin layers of various metallic materials to the surface of glass during the manufacturing process, thermal performance of the glass is greatly enhanced. Low-E coatings are an excellent alternative to dramatically increase the energy efficiency of glass. Further information including specific performance data can be found in the Glass Choices / Performance section of this website.

Warm-Edge Technology

For ultimate energy performance, advanced technology has allowed for the development of a spacer made of stainless steel. Stainless spacers are both structurally strong as well as warm edge: ideal for high performance commercial applications. Warm-Edge technology can best be described this way: the IG unit insulates interior and exterior environments best where the glass is separated by air space. However, a “bridge” of temperature transmission is created between these environments where glass is bonded to the spacer. Although our aluminum spacers still offer performance, stainless conductivity is less than 10% of aluminum. IG units utilizing warm-edge spacers and Low-E glass assist in reducing condensation within the structure around the windows, which can lead to mold or other problems if condensation is not properly weeped.

Offset Units

Occasionally, architects desire buildings to have the appearance of an all glass look, with minimal space between the units, and with no vertical framing visible from the exterior sight plane. To do this, the interior glass and spacer is positioned further from the glass edge, allowing space for the structural framing to support the insulated unit from behind the exterior lite. The space between “butting” lites is sealed with structural silicone. Today, Craftsman is one of the few US manufacturers capable of producing offset units on an automated robotic line, giving a more quality, clean look desired for the building exterior.

Breather Tubes

Breather Tubes are very thin stainless steel tubes inserted through the spacer bar to equalize pressure inside the IG unit to that on the outside. Craftsman recommends that Breather Tubes be installed in IG units if the altitude differential at the jobsite or during transport exceeds 2500 ft. from our factory. The tubes must be immediately sealed upon arrival at the jobsite. Breather Tubes are installed on the vertical edge of an IG Unit and sealed by crimping the tube closed in 2 spots and bending the tube downward along the vertical edge.