IR 24-1: Glass Panel Railings: 2022 CBC

IR 24-1 (Revised 06/14/23) Page 1 of 3

DIVISION OF THE STATE ARCHITECT DEPARTMENT OF GENERAL SERVICES STATE OF CALIFORNIA

IR 24-1

GLASS PANEL RAILINGS: 2022 CBC

Disciplines:

Structural, Fire and Life Safety History: Revised 06/14/23 Under 2022 CBC

Last Revised 06/12/20 Under 2019 CBC

Original Issue 09/01/99

Division of the State Architect (DSA) documents referenced within this publication are available

on the DSA Forms or DSA Publications w

ebpage.

PURPOSE

This Interpretation of Regulations (IR) clarifies requirements for glass panel railings for use on

construction projects under DSA jurisdiction.

SCOPE

This IR is applicable to the design and construction of glass panel railings. Glass panel railing

refers to a railing assembly, consisting of glass panels cantilevered from a base with or without

a continuous rail at the top. This IR defines three compliance options for glass panel railings as

follows: design method (refer to Section 2 below), test method (refer to Section 3 below), or

evaluation report validation (refer to Section 4 below).

BACKGROUND

California Building Code (CBC) Section 2407 addresses glass used in handrails and guards

including material properties and other requirements. CBC Section 1607A.9 defines live load

requirements for handrails and guards. When used in exterior applications, glass panel railings

are also subject to wind loads prescribed by CBC Section 1609A and American Society of Civil

Engineers Standard 7: Minimum Design Loads and Associated Criteria for Buildings and Other

Structures (ASCE 7).

1. GENERAL

Glass panel railings shall be designed and constructed in accordance with CBC Section 2407.

The system shall be designed so that the top rail remains in place in the event of failure of an

individual glass panel. The CBC does not require a continuous rail at the top if certain

requirements are met per the exceptions in CBC Section 2407.1.2.

1.1 Material

Glazing in railing panels shall be an approved safety glazing material that conforms to CBC

Sections 2406.1.1 and 2407.1.

1.2 Design Loads

Glass panel railing systems shall be designed for all the applicable loads combined in

accordance with CBC Section 1605A.

1.2.1 The required vertical and horizontal live loads for glass panel railings are prescribed in

CBC Section 1607A.9.1 including distributed and concentrated loads.

1.2.2 For exterior installations, the design shall account for wind loads as required by CBC

Section 1609A and ASCE 7.

1.3 Deflection Criteria

The deflection at the top rail resulting from the horizontal loads per Section 1.2 above shall not

exceed the following limits when combined in accordance with the allowable stress design load

combinations. Refer to CBC Section 2403.3.

IR 24-1

GLASS PANEL RAILINGS: 2022 CBC

IR 24-1 (Revised 06/14/23) Page 2 of 3

DIVISION OF THE STATE ARCHITECT DEPARTMENT OF GENERAL SERVICES STATE OF CALIFORNIA

1.3.1 Cantilever elements:

1.3.1.1 Length (L) no more than 13’-6”: L/90.

1.3.1.2 Length (L) greater than 13’-6”: L/120 + 1/8-inch.

1.3.2 Simple span elements:

1.3.2.1 Length (L) no more than 13’-6”: L/175.

1.3.2.2 Length (L) greater than 13’-6”: L/240 + 1/4-inch.

1.4 Location

Glass panel railings shall not be used in locations where they may be subject to vehicle

impact, in accordance CBC Section 2407.1.3.

2. DESIGN METHOD

The glass elements of the handrail assembly and the connections thereto shall be designed for

a safety factor of four in accordance with CBC Section 2407.1.1. Compliance with the latest

version of the Engineering Structural Glass Design Guide published by the National Council of

Structural Engineers Association (NCSEA) is an acceptable means of substantiating the

structural adequacy of glass panel railings. Mechanical properties of the glass upon which the

design is based, such as modulus of rupture, modulus of elasticity, allowable stress, etc. shall

be specified on the construction documents.

3. TEST METHOD

Glass panel railings may be accepted based on adequate performance under load testing.

Tests may be conducted in the field or in the laboratory. Mock-ups tested as evidence of

acceptability shall be exact duplicates of each unique railing configuration.

3.1 Test Protocol

All tests shall be performed by a DSA-accepted testing laboratory. Tests shall be observed, and

results recorded in a report signed by a California registered civil or structural engineer per CBC

Section 2403.2. The test program shall be defined on the construction documents per Section

3.4 below and include tests for both strength per Section 3.2 below and serviceability per

Section 3.3 below.

3.2 Strength Test

Test loads shall be applied horizontally and perpendicular to the top rail as follows:

3.2.1 Glass elements shall be subjected to a test load equal to four (4.0) times the maximum

horizontal force per Section 1.2 above based on allowable stress design load combinations.

3.2.2 Non-glass elements shall be subjected to a test load equal to two and one-half (2.5)

times the maximum horizontal force per Section 1.2 above based on allowable stress design

load combinations.

3.2.3 Alternately, glass and non-glass elements may be tested together using the test loads

required by Section 3.2.1 above.

3.2.4 Acceptance criteria for the tested glass panel railing includes the following:

3.2.4.1 No damage is observed in the glass or non-glass elements, including cracking,

yielding, fracturing, fastener loosening, etc.

3.2.4.2 No permanent or residual deformation is observed in the system. The top rail shall

recover to its original position upon release of the test load.

IR 24-1

GLASS PANEL RAILINGS: 2022 CBC

IR 24-1 (Revised 06/14/23) Page 3 of 3

DIVISION OF THE STATE ARCHITECT DEPARTMENT OF GENERAL SERVICES STATE OF CALIFORNIA

3.3 Deflection Test

Test loads shall be applied horizontally and perpendicular to the top rail as follows:

3.3.1 The system shall be subjected to a test load equal to the maximum horizontal force

per Section 1.2 above based on allowable stress design load combinations.

3.3.2 Deflections measured under the load applied per Section 3.3.1 above shall comply with

the criteria defined in Section 1.3 above.

3.4 Construction Documents

Construction drawings shall clearly identify the quantity and types of glass panel railings to be

tested. At least one set of tests (i.e., strength and deflection) shall be performed for each unique

railing configuration.

3.4.1 Drawings shall identify the locations of in-situ glass panel railings to be tested or for

which an equivalent mock-up is to be made for testing purposes.

3.4.2 Drawings shall clearly define the magnitude, location, direction, rate, and duration of

loads to be applied in accordance with Sections 3.2 and 3.3 above.

3.4.3 Testing requirements for glass panel railings shall also be indicated on the form

DSA-103: List of Required Structural Tests and Special Inspections.

4. EVALUATION REPORT VALIDATION

DSA will accept a qualified evaluation report issued by a certified product evaluation

organization complying with the requirements of IR A-5: Acceptance of Products, Materials, and

Evaluation Reports. An acceptable report will state that the product complies with International

Code Council Evaluation Service (ICC-ES) Acceptance Criteria AC439. In addition to the

evaluation report, structural calculations shall demonstrate compliance with the deflection

criteria in Section 1.3 above.

REFERENCES

2022 California Code of Regulations (CCR) Title 24

Part 2: California Building Code (CBC), Sections 1605A, 1607A.9, 1609A, 2403.2, 2403.3, 2406.1.1, 2407,

2407.1.1, 2407.1.2, and 2407.1.3.

This IR is intended for use by DSA staff and by design professionals to promote statewide consistency for review and

approval of plans and specifications as well as construction oversight of projects within the jurisdiction of DSA, which

includes State of California public schools (K‒12), community colleges and state-owned or state-leased essential

services buildings. This IR indicates an acceptable method for achieving compliance with applicable codes and

regulations, although other methods proposed by design professionals may be considered by DSA.

This IR is subject to revision at any time. Please check DSA’s website for currently effective IRs. Only IRs listed on

the webpage at https://www.dgs.ca.gov/dsa/publications a

t the time of project application submittal to DSA are

considered applicable.