Designing from the floor up

The New Jersey State Complex features Jockimo GlassGrit Privacy Frost glass flooring. Made of low-iron glass, the custom glass floor incorporates unique, frosted designs laminated within the glass. Floor design is by Mik Young Kim.

Jockimo's Crystal Clear glass flooring panels allow visitors to Ontario's Waterloo Region Museum to see the original railroad tracks beneath the floor. Floor design is by Moriyama & Teshima Architects. KW Glass Systems Inc. was the glass installer for the project. Photo by Jockimo Inc.

As the popularity of glass flooring has increased, so has the need for a standard governing its performance, design and safety characteristics. In 2006, a group of industry specialists—including glass flooring manufacturers, laminators and engineers; float glass  manufacturers; consultants; safety experts; and resellers from around the world—recognized  that need and began developing a new ASTM standard for glass flooring. After a lengthy but  productive process, that standard was published in January 2012 as ASTM E2751-11:  Standard Practice for Design and Performance of Supported Glass Walkways.

Developed as a tool for designers, the new standard "will require glass flooring suppliers to test their systems, if they are not doing so already," explains Valerie Block, chair of the E06.56 ASTM subcommittee that developed the standard, and senior marketing specialist for DuPont Glass Laminating Solutions.

ASTM E2751-11 addresses performance, design and safety considerations associated with  load-bearing glass walkways, glass treads and glass landings constructed with laminated  glass; as well as characteristics unique to glass and laminated glass. Issues that are common to all walkways, such as slip resistance, are addressed in existing referenced standards. To download a copy of the new standard, visit www.astm.org.

When specifying glass flooring products, it's important to take the following characteristics and ASTM requirements into consideration, with the safety of the building occupants being of utmost concern. 

ADA-compliant, anti-slip walking surface

The anti-slip walking surface needs to exceed the Americans with Disabilities Act coefficient of friction requirement of 0.5. Accordingly, ASTM E2751-11 recommends a minimum coefficient of friction of 0.5 for dry conditions. The ASTM glass flooring standard cites several testing  procedures to verify COF, including:

• UL-410: Standard for Safety for Slip Resistance of Floor Surface Materials
• ASTM C1028 - 07e1: Standard Test Method for Determining the Static Coefficient of Friction of Ceramic Tile and Other Like Surfaces by the Horizontal Dynamometer Pull-Meter Method, and
• ASTM F609 Test Method for Using a Horizontal Pull Slipmeter.

It is anticipated that the first revision of ASTM E2751-11 will have at least two other provisions: the inclusion of ANSI/NFSI B101.1-2009 Test Method for Measuring Wet SCOF of Common Hard-Surface Floor Materials as an approved test procedure, as well as a requirement that
all testing be completed by independent laboratories or agencies. Future work on the ASTM glass flooring standard will more than likely examine COF issues related to wet surfaces and
non-level walkways as well.

Various anti-slip surfaces are available that meet ADA requirements, including a glass aggregate that is melted into the top walking surface of the glass and still maintains a clear look. Ceramic frit is another option; it is silk screened onto the top of the glass, much like a t-shirt is printed. The product is then baked onto the top walking surface during the glass tempering process.Acid-etched products are another viable solution for anti-slip glass walking surfaces.

Glass composition and structural integrity

The glass should adhere to the new ASTM E2751-11 standard's requirement that all two-ply systems undergo physical testing. Three-ply systems may be verified via finite element analysis. ASTM E2751-11 also requires manufacturers to conduct pre- and post-breakage analysis. Additionally, the standard clearly states that a glass flooring panel must support a concentrated load of 300 pounds applied to all glass walking surfaces in a 4-inch by 4-inch area.

To assure structural integrity, work only with an experienced manufacturer/supplier. Use a structural glass engineer to determine the composition of the glass panels. Many manufacturers offer their own engineering for a small fee.

Modesty/ Privacy

When specifying a glass flooring product, review the privacy aspects of the installation. In public applications, an obscure product should be used so that improprieties do not occur. The obscure product should still allow for light to pass through the glass. 

Durability and maintenance

Every glass flooring product should be durable and easy to maintain. Durability can be defined in terms of the glass flooring system's ability to maintain its safety, structural and aesthetic qualities. Safety durability issues primarily address anti-slip features. Aesthetic issues include chipping and scratching that compromise the flooring's appearance but not its function. While the E06.56 ASTM subcommittee had difficulty in determining quantifiable standards for these qualities, it is expected that industry experts will continue to explore if standards can be developed to address durability issues.

Daylight harvesting

Daylight harvesting is the practice of capturing light from an exterior wall by making adjacent walls and floors transparent so that light can travel freely through room interiors. In addition to reducing electricity costs, numerous studies have proven that daylight harvesting also improves building occupant comfort and performance. Glass flooring products can play an important role in daylight harvesting and should allow for the maximum amount of daylight to pass through. So, avoid opaque anti-slip material.

Exterior installations

Historically, laminated glass products have not worked well in exterior applications where the glass edges are exposed to the elements. However, the development of new and improved lamination products has eliminated this concern, allowing glass flooring products to be used in exterior applications. When designing for exterior applications, it is imperative to address any water retention or sealant issues. Water retention on the walking surface can compromise the glass floor's safety and structural integrity.