Safer Schools:
Making
the Grade

A. Like most glass, fire-rated glazing allows light and visibility for aesthetic or security reasons. But fire-rated glass does something more: It acts as a barrier to the spread of flames and smoke, containing it within a limited space. In the world of fire protection, this is known as “compartmentation.”

Unlike sprinklers or other “active” protection systems, fire-rated glass does not require activation in order to protect against fire. If there is a power failure, a loss of water pressure, or a human error that interferes with the sprinklers working properly, fire-rated glass will not be affected and will continue to perform as needed.

A. Explore the two types of glazing systems to understand: “fire-protective” and “fire-resistive.” While they sound similar, there are some distinct differences between the two.

Fire-Protective

Fire-protective glazing can be counted on to defend against the spread of flames and smoke for a designated amount of time, which is indicated by a fire rating. This type of glazing is available with fire ratings from 20 to 90 minutes depending on the glass.

Fire-Resistive

In addition to blocking flames and smoke, fire-resistive glazing products limit the transfer of heat through the glass. This adds another layer of safety and makes the glass suitable for use in doors, walls and other fire-rated assemblies that are required to block the passage of excessive heat, hot gases and/or flames.

This type of glazing can typically be used where building codes require an assembly designated “fire resistant” to enclose a space.

Fire-resistive glazing is tested to the same standards as solid barrier walls, and therefore is not limited to 25 percent of the wall as is fire-protective glass. This type of glazing is versatile in design since it eliminates the need for opaque materials such as masonry or gypsum in areas that require fire-rated walls and allows for virtually unlimited expanses of glass.

A. A school’s fire-rated areas are subject to the same impact safety standards as non-rated areas. The chances of fire may be slim, but the danger of breakage looms daily. A door at the end of a school hallway may have to endure regular contact with students who push, press and slam their way through.

Glass in hazardous locations must meet impact testing requirements, as well as fire testing. As with fire ratings, impact safety ratings offer different levels of resistance, depending on the need. The highest rated products are strong enough to withstand the force of a full-grown adult running into them.

A. Safety and security may sound synonymous, but when it comes to glazing, they are technical terms that refer to separate categories of glass.

Safety Glazing

One of the most common forms of safety glazing is impact-safety-rated glass. As mentioned earlier, impact safety ratings measure a product’s ability to offer protection against accidental human impact. This not only indicates that it will resist breakage—it also means that if broken, the glass will do so in a manner that will not leave dangerous shards. This is why at the scene of an auto accident you will find small beads of glass rather than large, sharp-edged pieces. The glass must break in such a way that it will not become a source of further injury.

Besides human impact, some forms of safety glazing also account for natural causes of breakage as well. These can include hurricanes, tornadoes, earthquakes and wind load.

Security Glazing

Like safety glass, security glass also offers protection. Specifically, security glazing is that which protects from forced entry, ballistics, and blast. This type of glass can also be bullet resistant and blast resistant.

For example, in the event of an intruder attack, forced entry glass gives students and staff the upper hand by taking away the element of surprise at access points and delaying ingress.

Security glazing is also available with fire ratings. It helps ensure the product meets all performance criteria, and isn't prioritizing security over safety, and vice versa.

A. While building codes require the use of fire-rated glazing in specific applications, they do not currently mandate the use of security glazing in educational facilities. However, the industry is working to tighten regulations. In 2018, at least 53 new school safety laws were passed in states, and districts are spending millions of dollars to “harden” schools with improved security measures.

A. More than 40 different voluntary tests apply to security issues, from forced-entry to ballistics to blast-resistance. However, building codes do not currently mandate security glazing in educational facilities.

With the groundswell of interest in making schools safer, task groups such as American Society for Testing and Materials, International (ASTM) are working diligently to reach consensus on a security test standard. And other parties (like the National Glass Association) are looking at ways to provide manufacturing guidelines for school security glazing in the interim.

Some school districts are not waiting for industry-wide standardization, but are adopting the voluntary security standards to enhance the protection of their students. Of all the existing tests, ASTM E2395 is most applicable to slowing down unskilled or semi-skilled intruders. This test of window and door systems projects pieces of 2” x 4” lumber from an air cannon at the glass. The same glass is then struck multiple times with a ball-peen hammer.

When it comes to bullet-resistant security glazing, UL 752 is the test standard most commonly referenced. Rounds of different types of ammunition are fired at the glass from a distance of 15 feet. A piece of corrugated cardboard is placed 18 inches behind the glass as a “witness plate.” A successful test will not only mean the glass stopped the ammunition, but also no spalling from the glass reached the cardboard. Ratings are assigned in levels from 1 to 8, able to stop a 7.62 mm rifle lead core full metal copper jacket, military ball from a submachine gun or assault rifle.