Glass Railings: Critical Code Considerations
Architects looking for clean sightlines, more transparency, and an all-glass look will find many options in today’s glass railing systems, including prefabricated unitized systems and exposed edges. Designed with safety and aesthetics in mind, glass railing systems help to open up interior spaces and connect buildings with nature in exterior applications.
They must be engineered to meet IBC code requirements, so safety is paramount. The type of glass railing system, components, and installation method selected must together meet local building codes for safety and performance. Many complications can be avoided if architects, contractors, and other project stakeholders communicate with the local authority having jurisdiction early in the planning process, as standards and requirements vary from region to region.
The ICC updates its International Building Code (IBC) every 3 years. Most of the country is currently following either IBC 2012 or IBC 2015. The ICC website offers an interactive map that is a good place to start when researching building code adoption in a specific state.
IBC-ICC ESR-3269 4.2.4: A top rail is required for a code-compliant guard installation. A cap rail is the same as a top rail and the two terms can be used interchangeably.
- Exception: A top rail is not required where the glass balusters are laminated glass with two or more lites of equal thickness and the same glass type. This must be approved by the local building official.
- Recommendation: Specify a rigid Ionoplast interlayer when not using a top rail to ensure structural integrity and post-breakage performance.
Testing performed on laminated glass can demonstrate the strength difference between a PVB interlayer and an Ionoplast interlayer. Both lites of glass are attached to the same base shoe using the dry-glaze installation method. Both lites are tempered and of the same thickness as well. An impact test using a small wrecking ball reveals that the PVB interlayer glass lite fails and folds over. The glass lite with the Ionoplast interlayer cracks but does not fold over. As previously mentioned, the Ionoplast interlayer is also recommended in exterior applications with exposed edges as a PVB interlayer can lead to the glass lites delaminating over time.
2015 IBC Code Changes
The biggest change the railing industry has faced regarding code occurred in 2015 IBC section 2407. In short, all glass used in a handrail assembly or guardrail installation must be laminated tempered glass unless there is no walking surface beneath or the walking surface is permanently protected from the risk of falling glass.
2407.1 Materials: Glass used as a handrail assembly or a guard section shall be constructed of either single fully tempered glass, laminated fully tempered glass or laminated heat-strengthened glass. Glazing in railing in-fill panels shall be of an approved safety glazing material that conforms to the provisions of Section 2406.1.1. For all glazing types, the minimum nominal thickness shall be 1/4-inch (6.4 mm). Fully tempered glass and laminated glass shall comply with Category II of CPSC 16 CFR 1201 or Class A of ANSI Z97.1, listed in Chapter 35.
Exception: Single fully tempered glass complying with Category II of CPSC 16 CFR Part 1201 or Class A of ANSNI Z97.1 shall be permitted to be used in handrails and guardrails where there is no walking surface beneath them, or the walking surface is permanently protected from the risk of falling glass.
Other materials in glass railing systems should conform to the relevant building codes listed below.
- Aluminum Components: Conform to ASTM B 221/ASTM B221M, Alloy 6063-T52
- Stainless Steel Components: Conform to ASTM A 666, Type 304 & 316
- Brass Components: Conform to ASTM B 248, No. 260, Yellow Brass
- Note: Avoid low quality substitutions to lower costs
Regional Code Adoption – Finite Element Analysis
Local municipalities may adopt a different edition of the IBC or they may have their own unique building code regulations altogether. For example, New York City uses portions of IBC 2012 and IBC 2015 for determining wind loads. While the city of Chicago requires Finite Element Analysis (FEA) models for glass used in guardrail applications. Engineering firms can use two different FEA modeling software packages: SJ Mepla Modeling Software and RISA Plate Modeling Software.
ADA Standards for Accessible Design
The IBC is not the only code that architects and contractors must adhere to. All new construction is also subject to Title 3 of the Americans with Disabilities Act of 1990, which sets accessibility standards for public and commercial facilities.
ADASAD 505: Handrails
Handrails are required on ramp runs with a rise greater than 6 inches (150 mm) and on certain stairways. Handrails are not required on walking surfaces with running slopes less than 1:20.
ADASAD 505.4: Height
Top of gripping surfaces of handrails shall be 34 inches (865 mm) minimum and 38 inches (965 mm) maximum above the walking surfaces, stair nosings, and ramp surfaces. Handrails shall be at a consistent height above walking surfaces, stair nosings, and ramp surfaces.
ADASAD 505.6: Clearance
Clearance between handrail gripping surfaces and adjacent surfaces shall be 1-1/2 inches (38 mm) minimum.
Not all codes are applicable to all glass railing systems, and a lot depends on specific project parameters. It has been said before, but cannot be understated, always consult the local code official as jurisdictions interpret and apply codes in different ways. Remember that a top rail is mandatory for any railing with monolithic tempered glass, but if laminated tempered glass is used, it may not be required.
Performance Requirements and Considerations
When it comes to performance requirements for glass guardrail systems, the applicable physical loads need to be identified in the specifications. The glass railing system must comply with the International Building Code, International Residential Code, and/or Americans with Disabilities Act, depending on the application.
The ICC Evaluation Service (ICC-ES) is the most widely accepted and trusted authority in performing technical evaluations for IBC compliance. Manufacturer-supplied ICC-ES evaluation reports give architects peace of mind knowing that the glass railing system will be accepted by code officials in projects nationwide.