What To Do About Wired Glass in Schools?

Wired glass is common in older school buildings and poses significant safety issues.

What To Do About Wired Glass in Schools?

Photo via Adobe, by Tom

According to the National Center for Education Statistics, there are more than 132,000 K-12 schools in the U.S. alone and these learning centers educate an estimated 76.4 million children and adults each year.

For many school buildings built before 2006, wired glass is in extensive use and was used to help provide a firestop in hallways, stairwells, classrooms and areas where people pass through. However, through a hard series of lessons, wired glass when broken can cause severe injury.

First introduced in the 1890s, wired glass is made by placing steel wire mesh in the glass while it is still soft during the manufacturing process. One of its purposes is to help hold the glass together under fire conditions to provide a temporary block to fire spread in a building, which  may help contain a fire and also provide time for people to leave the building.

Because of this, one of its more popular applications has been installations in stairwell doors, elevators, gymnasiums, hallway doors and sidelights in school buildings. To look at an installation of wire glass in a door, one would assume it would make the glass stronger. In fact, the wire is a weak link in the glass and it may be broken more easily when impacted.

Although it was known that wired glass would break more easily than even standard annealed glass without wire, it was given an exemption in various building codes, as there really was no alternative. Generally, safety glazing is required to comply with the Consumer Product Safety Commission’s standard 16 CFR 1201, but as noted, an exception allowed “polished wired glass” in doors and windows that are part of a fire-resistance-rated assembly to comply with the less restrictive standard, ANSI Z 97.1.  For this reason, many people believed it was a type of safety glass when, in fact, it was really only annealed glass with wire in it.

By 2006 and after a lengthy, multi-year process, the International Building Code Council removed the exemption for wired glass, which meant it must comply with the more stringent impact requirements of 16 CFR 1201.

This effectively banned the installation of traditional wired glass from all areas subject to human traffic (close to the floor or stairs) in schools, known in the Code as Group E and defined as a structure for the use by six or more persons at any one time for educational purposes through the 12th grade. Allowable uses could be areas that considered to be out of reach of most human traffic such as transoms.

While new installations would not meet code in schools, existing installations can remain as long as they met the existing code when originally installed. But this reality presents a serious problem. Imagine the result of a hard charging teen moving quickly through a hall and instead of hitting the panic bar on a door, their hand and arm goes through wire mesh glass.

Since annealed glass is so easily broken, wired glass may cause severe damage to arm or leg muscles, ligaments, tendons, nerves and blood vessels, both during the initial impact and even more so when there is an attempt to pull the victim away.

It’s Only a Matter of Time Before Someone Gets Hurt

The presence of wired glass in a school may mean it is only a matter of time before a serious injury occurs. In fact, multi-million lawsuits against school districts, cities and private educational organizations have been won by families who had a child severely injured by wired glass.

  • Kent State Washington Unified School District paid $2 million and an apology to a family whose son severed their arm after going through wired glass
  • The Halton Catholic District School Board in Ontario, Canada paid $5 million to a family following injuries to their son’s arm after it went through wired glass
  • While no recent studies have been done, a study by Dr. Philip L. Graitcer of Emory University did back in 2003 estimates more than 2,500 wired glass injuries per year in schools alone.

Building Surveys Can Identify Areas with Wired Glass

A complete building survey should be conducted as soon as possible to identify all areas with wired glass that are accessible to routine human traffic. In fact way back in 2006 the New York State Education Department Office of Facilities Planning (NYSED Facilities & Planning Newsletter 73 – March 2006), states: “We strongly recommend that all existing wire glass locations be evaluated for potential impact and injury. There are several alternatives available to remedy locations determined to be at risk, such as replacement with impact and fire resistant materials, coating the glass with specialty films and installing protective bars or railings.”

Since ordinary glass shatters when exposed to fire and wired glass is no longer an option for schools, the only options are to replace glass sections that would likely be impacted by people in areas of travel fire-rated glass or to retrofit the wired glass with some type of safety film. Fire rated glass sections average about $100 a square foot in costs without installation.

Back in early 2000, being aware of the problem, the Window Film Committee of AIMCAL (which became the Manufacturers Committee of the IWFA in 2010) had a well-known fire testing laboratory complete a test of a generic 8-mil film thick as applied to wired glass and concluded that, “the retro-fit addition of the safety film to fire-rated glazing systems tested did not have any effect on the performance of the wire glass during fire exposure.”

In general, window film is Class A Fire Rated and has passed ASTM E-84 Flame Spread/Smoke Testing criteria. Class A Fire Rated Window Film Products provide one hour or greater protection and can help control the spread of fire. Class A material involves organic, solid materials such as wood, paper, cloth, rubber or plastics (window films) that do not melt or burn below a specific temperature.

The ASTM E84 fire-test is conducted in a rectangular fire observation chamber, a tunnel roughly 25 feet long, which provides a linear area for fire and smoke to propagate after ignition and be analyzed. The purpose of this test method is to determine the relative burning behavior of polyester film by observing combustion characteristics that are defined, such as: Smoke Generation, Time to Ignite, Rate of Burning and Flame Front.

In the event the wired glass was to shatter, the safety and security window film may hold broken glass fragments together in place, reducing or eliminating the risk of injury as a result of dangerous glass shards.

The IWFA recommends that safety and security window film be applied to at least the side of a wired glass installation which is subject to human impact. An 8-mil security clear film without any coatings is expected to have a puncture strength of 170 pounds or more.  Such an installation could be further reinforced by the application of edge silicone around the circumference of the installation. Window film installed in the interior of a building may have a lifespan exceeding 20 years.

For exterior windows with wire mesh, ‘plain’ safety and security window films should be installed on the interior, as opposed to films with energy-saving features, which could contribute to spontaneous glass breakage due to heat build-up in the wire. Exterior solar security window film may be installed if energy savings is also required.

Given the complexities of options in building codes and the technical nature of window film products, it is important to consult with a window film manufacturer about a product’s fire and safety ratings and listings.


Darrell L. Smith is the executive director of the International Window Film Association. He also serves on boards or committees of the National Fenestration Rating Council, National Glass Association, the Protective Glazing Council International, and the Glazing Industry Code Committee, and represents the industry in dealing with the California Public Utilities Commission , the California Energy Commission, the International Code Committees, and the U.S. Department of Energy and U.S. Environmental Protection Agency.

Note: The views expressed by guest bloggers and contributors are those of the authors and do not necessarily represent the views of, and should not be attributed to, Campus Safety magazine.

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