What Code Standards to Work to When Installing Glass Railing Systems
Q: With complexities and variance in code adaption that effect glass and glass railing systems state-to-state and locally, how can installers more easily determine what code standards to work to when installing glass railing systems?
As railing systems are often installed at project-end, time is rarely on the side of the glaziers or fabricators doing the installation. While getting in and out of the job as quickly as possible and doing quality work are critical for profitability, compliance considerations are as critical and can create costly delays if not properly specified or installed to code. That’s not made any easier in that navigating code compliance can be confusing.
Currently, the IBC 2015 (International Building Code) is the model code to which all states and jurisdictions should be heading. What IBC 2015 essentially impacts in regards to glass railings systems is glass requirements, top-rail use and by association glass-edge appearance. Yet as it currently stands, only 15 states have adapted it as their model code with many still using IBC 2009, the previous update year. That’s not to mention code requirements also vary by local jurisdiction, as installers are well familiar. So, in light of IBC 2015 as the ideal model code – but also among the variance of its adaption – I tell those involved in railing installations with glass to start by looking at four things to get a better handle on compliance:
1. Understand if tempered-laminated glass should be used
2. Know how top-rail is required
3. Be familiar with ASTM standards for edge tolerance
4. Consult the Authority Having Jurisdiction to confirm before installation
Tempered-laminated Glass vs. Monolithic Tempered Glass: IBC 2015 requires fully tempered or heat strengthened laminated glass meet Category 1 or Class A impact requirements with the intent to protect individuals from falling glass. Per IBC, monolithic tempered glass as Category 1 or Class A is only allowed where there is no walkway under the glass, or if the walking surface is permanently protected from the risk of falling glass. Everywhere else it has to be tempered laminate.
The Inclusion of Top-Rail: IBC 2015 also requires all glass systems be designed with a top-rail in order to hold the glass in place should it break. The one exception is when the glass system uses laminated glass of equal plies of the same thickness and with panels designed to withstand loads as specified in IBC 1607.8 – link. From an installation standpoint, remember to use a design factor of four with the additional caveat that the building official Authority having Jurisdiction has to first approve the installation and advise as to which version of the IBC codes apply in your area.
Edge Appearance: With the use of tempered laminate glass comes the issue of exposed edge appearance and by default the tolerance of the visible exposed edges. For this the realm of standards for tolerance falls not just under IBC 2015, but under ASTM Standards. When a top-rail is not-required, or the glass is used as a four-edge supported infill panel, the quality of the visible edges from both a safety and aesthetic perspective becomes all the more important. Architects and specifiers expect the edge quality to be uniform whether laminated or monolithic glass is used. This expectation is obviously more of a challenge in the case of laminated glass; meanwhile, the industry is currently in the process of reviewing how to appropriately respond. Here is a link to ASTM resources for specifying edge tolerances with relevance to glass railing systems to provide clarity:
– ASTM C1036: Standard specification for flat glass
– ASTM C1048: Standard specification for heat strengthened and fully tempered flat glass
– ASTM C1172: Standard specification for laminated architectural flat glass
– ASTM E2353-06: Standard test methods for performance of glass in permanent glass railing systems, guards & balustrades
– ASTM E2358-04: Standard specification for the performance of glass in permanent glass railing systems, guards & balustrades
Authority Having Jurisdiction: While the best-case scenario from a safety standpoint would be universal adaption of IBC 2015, the fact remains that variance exists and will continue to exist. Where applicable and for a number of reasons ranging from aesthetics to costs, laminated glass, and top-rail don’t always find their way into the specifications used in design.
Understanding the keys associated with IBC 2015 including when to use laminated glass and top-rail, as well as ASTM standards for edge tolerance as it relates to laminated glass provide great help in determining what code to work to. But at the end of the day, ultimately it’s still your best bet to confer with the Authority Having Jurisdiction. Depending on location, this authority could include the fire marshal, building inspector, accessibility reviewer, and so forth. For assistance in determining the authority for the next job, your railing supplier can lend a hand to point you in the right direction.
Andrew Chatfield: Andrew Chatfield is the Director of Architectural Glass Systems for the Wagner Companies. With more than 25 years in the glazing industry in Europe and North America, Andrew has extensive experience working with architects, specifiers, installers and end users around the world in relation to glass, glass hardware and most recently in glass railing and balustrade systems, and code compliance.