Tag Archives: 08 81 00−Glass Glazing

Security Glazing for Safer Schools: Trends in School Safety

Between 1999 and 2009, various school security measures have been implemented:

  • controlled access to the building during school hours (moving from 75 to 92 percent in that decade);
  • controlled access to school grounds during school hours (34 to 46 percent);
  • identification badges for faculty (25 to 63 percent);
  • video cameras to monitor school (19 to 61 percent);
  • telephones in classrooms (45 to 74 percent);
  • student uniforms (12 to 20 percent);
  • restricted social networking websites (now 93 percent); and
  • restricted cell phone use during school hours (now 91 percent).

To read the full article, click here.

 

Security Glazing for Safer Schools

Photo courtesy Graham Architectural Products

Photo courtesy Graham Architectural Products

by Julie Schimmelpenningh

With recent tragedies involving school shootings, parents and administrators across the country are demanding ways to make K−12 facilities more secure. Areas of the schools under significant scrutiny are doors and windows—and more specifically, the glass being specified.

For extra school security, laminated security glass can be an easy and cost-effective measure to assist in resisting forced entry and the threat of bullets. Compared with traditional annealed or tempered glass, this type of material can secure the building more effectively.

Laminated glass is made from a tough plastic interlayer bonded between two pieces of glass. The interlayer is invisible to the naked eye, so laminated glass offers the same clear visual benefits as ordinary glass—an important feature for security. From inside, glass allows occupants to see someone approaching the school. From the outside, it can help responders locate intruders or victims.

Success in other fields
Laminated glass has successfully protected public facilities and major works of art for many years. Security glass has been in use in various forms for generations. Invented in 1903 by French chemist Edouard Benedictus, laminated glass has been employed for decades in car windshields to greatly reduce injuries. It is commonly used in high-risk facilities such as embassies and federal buildings, as well as museums. Laminated glass protects great treasures such as the Mona Lisa, the U.S. Constitution, and the Crown Jewels in London.

After the devastation caused by Hurricane Andrew in 1992, laminated glass became the standard in Florida and other coastal regions. Building code requirements were established to lessen the amount of destruction caused from high winds and to ensure occupant safety.

Enhancements to laminated glass configurations ensure glazing in federal and other public buildings are blast-resistant. Dozens of lives were saved by blast-resistant laminated glass when the Pentagon, newly remodeled, was attacked on September 11, 2001. The shockwaves following an explosion can send glass shards flying for miles and generally cause about 70 percent of the injuries following a blast, as was the case in the 1995 Oklahoma City bombing and many other blast events. It is these qualities that make the material a good candidate for school specifications.

When remodeling an educational facility or building a new school, security should be a major player in the design process. Windows and doors are the easiest point of entry into a school, but they don’t have to be.  Installing laminated security glass for all windows and doors makes forced entry much more difficult. Images courtesy Eastman Chemical Company

When remodeling an educational facility or building a new school, security should be a major player in the design process. Windows and doors are the easiest point of entry into a school, but they don’t have to be. Installing laminated security glass for all windows and doors makes forced entry much more difficult. Images courtesy Eastman Chemical Company

Renewed need for extra security
A school is more than just a facility; it is a place where families send their kids for the majority of their day to learn, participate in sports and clubs, and perform in musicals and plays. Schools can be why families buy a home in a specific neighborhood, and they can be what ties a community together—the buildings are frequently used as emergency management centers or shelters in times of crisis, making security an important attribute, even after teaching hours.

In recent years, however, schools are not being thought of as the safe havens they once were. Since 1992, there have been 387 shootings in U.S. schools, according to www.stoptheshootings.org. One of the most recent involving fatalities occurred last December at Sandy Hook Elementary School, where 20 children and six adults were killed. As no one can predict whether an attack will happen, it is important schools be prepared for anything.

Immediately following the Sandy Hook shooting, discussions across the country started about how this tragedy and future shootings could be prevented. There were conversations about gun control, awareness and care for the mentally ill, as well as improving safety at schools through better communication systems, security measures, and intruder drill training. School districts everywhere are looking at how they can keep their students, teachers, and faculty safe. Design/construction professionals can play an important role as well.

What the school construction industry can do
By installing laminated security glass for all windows and doors, forced entry becomes much more difficult. Laminated glass is fabricated with a tough, protective interlayer, typically of polyvinyl butyral (PVB), which is bonded with heat and pressure between two pieces of glass. The use of thicker interlayers can increase the resistance of the glass to impacts. Upon impact, laminated glass will shatter, but glass shards remain held together by the bonded interlayer. Risks associated with flying or falling glass are minimized.

Laminated security glass stands up to multiple assaults from a blunt or sharp object used to gain entry. If an intruder tries to break through a window or the glass lite of a door, it would take several blows before he or she achieves access through the security glass. This allows valuable time for anyone inside the school to react, enabling more opportunity to call the police, send internal communications about the intruder, lock-down interior doors or classrooms, evacuate, or move students to a safer area.

From a glazing standpoint, school architects and administrators may consider the following when designing new or retrofit glazing systems:

  • glass should provide inherent health, safety, and security benefits that can help mitigate disasters;
  • natural daylight is essential for psychological benefits of students and teachers;1
  • glass should provide visibility for critical passageways and entry areas; and
  • sustained functionality—basic functions of the school can operate following a natural disaster or incident.

Considering threat levels
Entry doors have been the most vulnerable in many school shootings. Hurricane-rated high-impact (i.e. large-missile) glass, or even ballistic glass should be considered. As in the case of Sandy Hook, the shooter penetrated the side lite of the door and then reached through to open it. The ‘break-and-reach’ ability of the intruder must be delayed or stopped. High-performance glass provides resistance, while still providing much needed visibility.

Existing doors may need to be replaced completely if bullet-resistant glazing is specified, as the framing system for such heavy configurations is specialized.

Access doors with a double-entry lobby to the school should be equipped with laminated security glazing having forced entry/burglary resistance capability in accordance with Underwriters Laboratories (UL) 972, Testing for Burglary-resistant Glazing Materials, or Class I of ASTM F1233, Standard Test Method for Security Glazing Materials and Systems.

Today’s schools have an increasing amount of glass windows and doors because of the positive benefits it brings. For extra security, laminated glass is an easy, cost-effective measure in protecting against forced entry and bullet resistance. Compared with traditional annealed or tempered glass, laminated glass can secure the building more effectively.

Today’s schools have an increasing amount of glass windows and doors because of the positive benefits it brings. For extra security, laminated glass is an easy, cost-effective measure in protecting against forced entry and bullet resistance. Compared with traditional annealed or tempered glass, laminated glass can secure the building more effectively.

First-floor glass should be, at a minimum, equipped with basic laminated glass, which typically requires a 0.76-mm (0.03 in.) thick interlayer. This type of glass will deter ingress, retain glass, and slow break-and-reach attempts. Forced ingress glazing will offer greater protection, and uses a thicker interlayer. Laminated glass can be retrofitted into most existing window and door systems and can contribute to compliance for security windows per ASTM E2395, Security Performance of Window and Door Assemblies With and Without Glazing Impact.

If budgets do not permit replacement of windows, security film can be post-applied over the existing windows and doors. This option offers some of the benefits of laminated glass, but provides less resistance against an intruder. Further, like other laminated glass options that are not ballistics-resistant, it will not stop a bullet. Security film also modifies the post breakage behavior of glass, but may allow time to take additional action versus non-enhanced glazing.

During new construction, laminated glass may make economic sense due to its higher performance levels. However, post-applied films can be a good alternative in a retrofit situation where glass replacement is not possible.

It requires several shots from handguns like a 9 mm, .357, or .45 caliber to make a hole large enough to put a fist through to unlock a door or window. In some cases, the intruder may be temporarily confused, as the glass does not ‘behave’ as expected. There are many documented smash-and-grab attempts at a burglary where would-be intruders give up because they are generating too much noise and attention.

Additional benefits
Along with its safety and security enhancing features, laminated glass offers other benefits for schools. Laminated glass dampens sound coming in from the outside, making it an ideal choice for schools located in noisy neighborhoods or urban environments. The interlayer in laminated glass significantly dampens sound, keeping unwanted outside noise at bay.

Numerous studies have shown children concentrate and can learn better in a quiet space. For example, one research project found links between higher achievement and less external noise. Excessive outside sound resulted in increased student dissatisfaction with their classrooms and stress.2

Laminated glass also reduces the amount of solar heat gain and ultraviolet (UV) rays going into a building, making it more comfortable and healthy for students and teachers. Work has been done delving into the importance teachers place on thermal comfort, proving temperature affects both teaching quality and student achievement.3 Interestingly, studies in the 1970s found the best temperature range for learning math and reading is between 20 and 23 C (68 and 74 F).4 Maintaining a specific classroom climate is an essential part of setting students up for success.

CS_February_2014.inddHurricane-rated laminated glass protects against natural disasters. Following Hurricane Andrew in 1992, Florida began to strengthen its building codes to help protect the building envelope. Windborne debris was a major problem during this Category 5 hurricane, and the construction industry began to look for ways to protect the windows in commercial buildings and schools.

Laminated glass proved to be one of the most effective solutions for this problem, and today, is commonplace in buildings in coastal areas of the United States, the Caribbean, and other world areas. Hurricane-resistant glass comprises multiple interlayers; it can be considered for vulnerable areas of a school, such as entry and rear doors, sidelites, and floor-to-ceiling windows.

Laminated glass is versatile, readily available, affordable, and easy to install. Also, it can be used to help a project earn credits within the U.S. Green Building Council (USGBC) Leadership in Energy and Environmental Design (LEED) program. Specifically, designers can secure points toward LEED certification under

  • Energy & Atmosphere (EA) Credit 1, Optimize Energy Performance;
  • Materials & Resources (MR) Credit 4, Recycled Content;
  • Indoor Environmental Quality (EQ) Credit 8, Daylight & Views; and
  • EQ Credit 9, Enhanced Acoustical Performance.

Since laminated glass offers solar, safety, and acoustic benefits, it can help achieve points ordinary glass may not.

Upgrading schools through glazing
In 1998, data collected in surveys conducted by the National Center for Educational Statistics (NCES) suggested the average public school building in the United States was 42 years old.5 This suggests many of the country’s schools may now be at an age where frequent repairs are necessary.

Due to the burst in school construction during the Baby Boom Era, the NECS study reports almost half (i.e. 45 percent) of schools were built between 1950 and 1969. Seventeen percent of public schools were built between 1970 and 1984, and only 10 percent after 1985. These older schools were not envisioned with modern-day security and safety measures in mind; further, they do not offer the physical security level now desirable.

Educator A.C. Ornstein found by the time school is 20 to 30 years old, frequent replacement of equipment is needed.6 Original equipment, including roof and electrical systems, should be replaced between 30 and 40 years old, as rapid deterioration begins after this point. In fact, most schools are abandoned by the time they reach 60 years.

When the NECS study was published, most of those facilities were already about 50 years old and experiencing serious decline. In other words, half of the country’s public schools could be seen as major threats to student safety.

Immediately following the Sandy Hook shooting, discussions across the country started about how this tragedy and future shootings could be prevented. School districts everywhere are looking at how they can keep their students, teachers, and faculty safe. Design and construction professionals can play an important role as well.

Immediately following the Sandy Hook shooting, discussions across the country started about how this tragedy and future shootings could be prevented. School districts everywhere are looking at how they can keep their students, teachers, and faculty safe. Design and construction professionals can play an important role as well.

Today, as the rate of school construction continues to decline, safety is a more serious concern than ever. The existing stock of schools is too old to offer any kind of reliable security systems. Outdated glass, in particular, lacks basic insulation features to control classroom temperature and cannot offer much more than protection from outdoor elements. However, the installation of laminated glass immediately updates an aging school and offers protection to students and teachers.

While there is pressing need for building better schools, many face funding and time constraints. When new buildings cannot be erected, the architectural community must look at available options to modernize, update, and safeguard existing schools. Laminated glass or window film remains one of the easiest and most cost-effective measures available for enhancing student and faculty safety.

Notes
1 For example, a 2002 study by L. Heschong et al (“Daylighting Impacts on Human Performance in School,” Journal of the Illuminating Engineering Society, 31[2])identified effects of natural light on students as evidenced in significantly improved standardized test scores for elementary students. The same study concluded that daylight contributed positively to overall health and well-being of students. (back to top)
2 The G.I. Earthman and L. Lemasters’ paper, “Where Children Learn: A Discussion of How a Facility Affects Learning,” was presented at the 1998 annual meeting of Virginia Educational Facility Planners. (back to top)
3 The 1999 J.A. Lackney report, “Assessing School Facilities for Learning/Assessing the Impact of the Physical Environment on the Educational Process,” was published by Mississippi State’s Educational Design Institute. (back to top)
4 The David P. Harner article, “Effects of Thermal Environment on Learning Skills,” appeared in Educational Facility Planner, 12 (2). (back to top)
5 The NCES report, “How Old Are America’s Public Schools?” was published in January 1999 by the U.S. Department of Education’s Office of Educational Research and Improvement. It can be read online at nces.ed.gov/pubs99/1999048.pdf. (back to top)
6 Ornstein’s article, “School Finance and the Condition of Schools,” appeared in the book, Teaching: Theory into Practice (Allyn and Bacon). (back to top)

Julia Schimmelpenningh is global applications manager, advanced interlayers for Eastman Chemical Company. She is has been a glass industry activist for 25 years with experience in research and development, technical lamination processing, product, applications, and standard development. Schimmelpenningh is a participating member of ASTM, International Organization for Standardization (ISO), and Glass Association of North America (GANA). She can be reached at jcschi@eastman.com.

To read the sidebar, click here.

Spontaneous Glass Breakage: Why it happens and what to do about it

Photo © Wes Thompson. Photo courtesy PPG

Photo © Wes Thompson. Photo courtesy PPG

by Michael L. Rupert

The past few years have seen several highly publicized incidents involving window and balcony glass breaking spontaneously and falling from high-rise buildings in Toronto, Chicago, Las Vegas, and Austin, Texas. While such episodes are rare, the danger they pose has forced building code writers, architects, government officials, and related industry professionals to reconsider which types of glass should be specified for glass applications where strength and protection of passers-by are paramount.

For architects and specifiers, it is important to have an overview on the potential causes of spontaneous glass breakage, including some common misconceptions about its actual spontaneity. The term ‘safety glazing’ generally refers to any type of glass engineered to reduce the potential for serious injury when it comes into human contact. In addition to balcony glass, safety glazings are commonly required for:

With an increase in spontaneous glass breakage incidents, the glazing industry is looking at new ways to make assemblies safer.  Images courtesy PPG Industries

With an increase in spontaneous glass breakage incidents, the glazing industry is looking at new ways to make assemblies safer. Images courtesy PPG Industries

  • sliding glass doors;
  • shower doors;
  • patio furniture;
  • skylights;
  • oven glass; and
  • automobile windshields.

Tempered, laminated, and heat-strengthened glass
The most common type of safety glass is tempered glass, which is made by heating pre-cut panels of glass to about 650 C (1200 F), then cooling them rapidly through a process called ‘quenching.’ By cooling the outer surfaces of the panel more quickly than the center, quenching puts the surfaces and edges of the glass in compression and the center of the glass in tension.

In addition to making tempered glass four to five times stronger than conventional annealed glass, re-heating and rapid quenching dramatically changes the break characteristics of the glass. Consequently, when tempered glass is broken, it shatters into thousands of tiny pebbles—this practically eliminates the danger of human injury caused by sharp edges and flying shards.

Another type of safety glazing, laminated glass, is made by sandwiching an interlayer of vinyl (typically polyvinyl butyral [PVB]) between two layers of glass to hold the panel together if it is broken. Although laminated glass is most commonly associated with windshield glass for automobiles, it is increasingly being specified for storefronts, curtain walls, and windows to meet codes for hurricane-resistant glass.

A third option, heat-strengthened glass, is not technically a safety glazing. This is because when it breaks, it may form larger sharp shards that can cause serious injury. However, heat-strengthened glass still meets Consumer Product Safety Commission (CPSC) 16 Code of Federal Regulations (CFR) Part 1201 and Class A of American National Standards Institute (ANSI) Z97.1, Safety Glazing Materials Used in Buildings−Safety Performance Specifications and Methods of Test, for many safety glass applications when it is combined with a laminated interlayer that holds the glass together if it breaks.

As with tempering, heat-strengthening involves exposing pre-cut glass panels to temperatures of up to 650 C, but with a slower cooling process. Heat-strengthened glass is not as strong as tempered glass because the compression strength is lower—about 24,130 to 51,710 kPa (3500 to 7500 psi) compared to 68,950 kPa (10,000 psi) or greater. However, it is about twice as strong as annealed glass. For this reason, heat-strengthened glass is often specified for applications demanding resistance to thermal stress and snow- and wind-loads.

Causes of glass breakage
The incidents of spontaneous glass breakage in Chicago, Las Vegas, Austin, Texas, and Toronto occurred exclusively with tempered glass. Despite that material’s high levels of strength and capacity to meet safety glazing requirements, it is uniquely vulnerable to these types of failures. Ironically, the center tension zone engineered into tempered glass through the quenching process is also what makes it so vulnerable to catastrophic breakage.

Safety glazings are commonly required for sliding glass doors, shower doors, and patio furniture. ‘Safety glazing’ generally refers to any type of glass that is engineered to reduce the potential for serious injury.

Safety glazings are commonly required for sliding glass doors, shower doors, and patio furniture. ‘Safety glazing’ generally refers to any type of glass that is engineered to reduce the potential for serious injury.

Poor edge quality
There are many potential causes for spontaneous breakage of tempered glass. The most common is damage to the edges of glass as it is being pre-cut into panels, or nicks or chips to the edges that occur when the glass is being packaged, shipped, or installed onsite.

While such damage may not be readily apparent, stress concentrations around these imperfections can occur as the glass expands and contracts in response to in-service temperature changes, wind load, building movement, and other environmental factors. Ultimately, when those stresses cause the glass to break, the action may appear to have been spontaneous when, in fact, the circumstances for failure had been put in place months or even years earlier.

Frame-related breakage

Expansion and contraction of glass framing members may also lead to frame-related breakage—another common form of seemingly spontaneous failure. Such incidents occur when the gaskets, setting blocks, or edge blocks in a metal window or curtain wall frame are missing or do not sufficiently cushion the glass against glass-to-metal contact caused by temperature or wind-related movement. This can cause edge and surface damage to the glass as it comes in contact with the metal frame’s perimeter, producing stresses that eventually lead it to fail for no apparent reason.

Thermal stress
Another potential cause of spontaneous glass breakage is thermal stress. Thermally induced stresses in glass are caused by a positive temperature difference between the center and edge of the glass lite, meaning the former is hotter than the latter. The expansion of the heated glass center results in tensile stress at the edge of the glass. If the thermally induced stress exceeds the edge strength of the glass, breakage occurs.

Accounting for thermal stress is especially critical today, as current design trends and the desire for daylighting are driving the industry toward the specification of larger insulating glass units (IGUs) with high-performance solar control coatings. Large IGUs have inherently greater glass surface and edge areas. When they are combined with coatings designed to manage the sun’s energy, more rigorous thermal stress analyses are required.

Nickel-sulfide inclusions

A far less common—but often cited—cause of spontaneous glass breakage is nickel-sulfide (NiS) inclusions in tempered glass. Small nickel-sulfide stones can form randomly in the production of float glass. They are typically benign, even when occurring in tempered glass.

North American glass manufacturers do not use nickel in batch formulations for primary glass and go to great lengths to avoid nickel-bearing components in their glass-melting processes. Despite rigorous quality controls and procedures aimed at reducing the likelihood of nickel-sulfide stones, there is no technology to completely eliminate their formation in today’s float glass.

Nickel-sulfide particles are tiny, extremely rare, and only found randomly in float glass. This combination makes visual inspection for such inclusions highly impractical—if not outright impossible.

Nickel-sulfide particles are tiny, extremely rare, and only found randomly in float glass. This combination makes visual inspection for such inclusions highly impractical—if not outright impossible.

There is no known technology that completely eliminates the possible formation of nickel sulfide stones in float glass. Further, because nickel sulfide stones are so small, there is no practical way to inspect their presence in float glass.

There is no known technology that completely eliminates the possible formation of nickel sulfide stones in float glass. Further, because nickel sulfide stones are so small, there is no practical way to inspect their presence in float glass.

Nickel-sulfide stones are quite small and their occurrence in the final glass product is covered under ASTM C1036, Standard Specification for Flat Glass, which permits blemishes (including nickel-sulfide particles) of between 0.5 and 2.5 mm (1/50 to 1/10 in.) in float glass, depending on glass size and quality.

While nickel-sulfide inclusions may be present in annealed or heat-strengthened glass, the problems they cause are specific to tempered glass because of the tempering process. Breakage is due to a volumetric growth in the size of the stone. As detailed earlier, during the annealing and heat-strengthening processes, glass is cooled at slower, controlled temperatures that enable nickel-sulfide particles that are present to complete a phase transformation (known as the ⍶ to β phase change) during which they fully expand to their final size and remain stable thereafter.

In the tempering process, this phase transformation is arrested during rapid quenching, which causes any nickel-sulfide particles present to remain confined to their shrunken, pre-transformation states. Then, when the tempered glass is exposed to higher in-service temperatures caused by solar heat gain or other high-temperature influences, nickel-sulfide particles have the potential to resume their volumetric growth. If the expansion is large enough—and the particle is located in the center tension zone of the tempered glass panel—the resulting stress may be enough to shatter the glass.

Is heat-soaking a solution?
As indicated, nickel-sulfide particles are tiny, extremely rare, and only found randomly in float glass. This combination makes visual inspection for such inclusions highly impractical, if not impossible. For that reason, some glass fabricators and glazing contractors offer heat-soaking of tempered glass as a potential solution for minimizing the risk of spontaneous glass breakage.

When tempered glass is broken (as shown above), it shatters into thousands of tiny pebbles, practically eliminating the danger of human injury caused by sharp edges and flying shards of glass.

When tempered glass is broken (as shown above), it shatters into thousands of tiny pebbles, practically eliminating the danger of human injury caused by sharp edges and flying shards of glass.

The surface compression of heat-strengthened glass makes it approximately twice as strong as annealed glass. Heat-strengthened glass is typically used when glass is required to meet thermal or mechanical loads caused by heat, wind, or snow.

The surface compression of heat-strengthened glass makes it approximately twice as strong as annealed glass. Heat-strengthened glass is typically used when glass is required to meet thermal or mechanical loads caused by heat, wind, or snow.

In this procedure, the glass supplier exposes an entire lot or statistical sampling of tempered glass panels to temperatures of 288 to 316 C (550 to 600 F) for two to four hours. The goal is to initiate or accelerate the phase change of any nickel-sulfide inclusions that may be present and to cause the glass to break before it is shipped to the end customer.

While this ‘break-now-instead-of-later’ procedure may eliminate defective tempered glass panels by destroying them before they are shipped, it cannot provide a 100 percent guarantee against spontaneous breakage. Even advocates of heat-soaking are careful to state the procedure can only reduce or minimize the risk for spontaneous breakage of tempered glass. They will not use words such as ‘prevent’ or ‘guarantee.’

Risks of heat-soaking
There are risks associated with the heat-soak procedure that may outweigh any perceived benefits. For instance, small, stable inclusions could undergo the beginning of a phase change during the heat-soak. While the phase change may not be sufficient to cause breakage during the procedure, the transformation could potentially continue after the glass is installed, causing it to break in-service.

Re-exposing tempered glass to the increased temperatures of heat-soaking also has the potential to reduce its surface compression, which is the source of its strength. Ultimately, this may undermine the glass’s ability to fulfill the safety or strength requirements for which it was intended.

Further, heat-soaking adds another layer of handling to the manufacturing process, which creates more opportunities for edge damage, scratches or color changes to the low-e coating, and other imperfections that could have an impact on the tempered glass unit’s long-term durability and performance.

As these illustrations demonstrate, the heat-strengthened glass and tempered glass have distinctive breakage patterns.

As these illustrations demonstrate, the heat-strengthened glass and tempered glass have distinctive breakage patterns.

Solutions for safety
In recent months, two organizations made major announcements prompted largely in response to the incidents of falling glass in Toronto, Chicago, Las Vegas, and elsewhere. Both shared a common assessment—namely, that using laminated tempered glass or heat-strengthened glass is the most viable solution to making balcony and other types of overhead glass safer.

In Canada, an Expert Panel on Glass Panels in Balcony Guards established by the Ontario Ministry of Municipal Affairs and Housing (MAH) recommended local building codes be amended to mandate the use of heat-strengthened laminated glass for any outboard guard or glazing located beyond the edge of a floor, or within 50 mm (2 in.) of the edge of a floor. For outboard glazings located more than 50 mm inward from the edge, the panel recommended heat-soaked tempered glass or heat-strengthened laminated glass.

Similarly, in December 2012, the International Code Council (ICC) passed a code change proposed by the Glazing Industry Code Committee (GICC), mandating use of laminated glass in handrail assemblies, guardrails, or guard sections. The newly approved code states laminated glass must be constructed of either single fully tempered glass, laminated fully tempered glass, or laminated heat-strengthened glass, and comply with CPSC 16 CFR Part 1201 or Class A of ANSI Z97.1.

San Francisco’s Intercontinental Hotel showcases the design trends and desire for daylighting, which are driving the industry toward specification of larger insulating glass units (IGUs) with high-performance solar control coatings. The architect of record is Hornberger + Worstell; the design architect is Patri Merker Architects.  Photo © Tom Kessler. Photo courtesy (BAH COURTESY IS MISSING IN THE MAG LOL) PPG Industries

San Francisco’s Intercontinental Hotel showcases the design trends and desire for daylighting, which are driving the industry toward specification of larger insulating glass units (IGUs) with high-performance solar control coatings. The architect of record is Hornberger + Worstell; the design architect is Patri Merker Architects. Photo © Tom Kessler. Photo courtesy PPG Industries

Fully tempered glass and heat-strengthened glass are made using the same basic heating and quenching process.

Fully tempered glass and heat-strengthened glass are made using the same basic heating and quenching process.

Conclusion
Given the developments and recommendations outlined in this article, it is clear a laminated glass interlayer in combination with tempered or heat-strengthened glass may offer the optimal blend of characteristics for applications where the risk of injury from glass fallout is a primary concern. For non-safety glass applications, where strength and resistance to spontaneous breakage is desired, non-laminated heat-strengthened glass should be considered due to its lower costs.

Michael L. Rupert is PPG Industries’ director of technical services and product development for flat glass. A 39-year company veteran, he is a board member for the Glass Association of North America (GANA) and chairs the Flat Glass Manufacturing Division. Rupert holds a bachelor’s degree in civil engineering and an MBA from the University of Pittsburgh. He can be reached at mrupert@ppg.com.