Third Party Verification Claim

Attachment 4: Physical Testing
July 13, 2020
Building Code Requirements
The International Building Code (IBC) and International Residential Code (IRC) are “model codes”
created by the International Code Council, intended to be used by states and municipalities as they
publish their own building codes. Section 1607.8 of the IBC requires that “handrails and guards shall be
designed to resist a linear load of 50 plf.” It also requires the system to resist a 200# concentrated load
that produces the “maximum load effect” on any element within the system. The 2018 IRC Table R201.5
extends this requirement into residential construction. It is understood within the building design
industry that loads applied to the top of the panel create the maximum load effect; structural design
assumes this loading condition.
Section 1607.8 of the IBC also refers to IBC section 2407 that adds a requirement for all-glass handrails
and guards to “be laminated glass constructed of fully tempered or heat-strengthened glass”; this
requirement was added in the 2015 IBC code cycle. Section 2407.1.1 adds the significant requirement:
“a design factor of four shall be used for safety”. This addition bumps up the linear load to 200 plf and
the concentrated load to 800#. Presumably, this is intended to prevent the glass from shattering and
injuring people below.
Exterior glass guardrail panels are designed to resist two load types: wind loads, and “live” loads such as
a person or object pushing on or striking the panel from the side or from above. Wind loading on a panel
can vary greatly based on location, terrain (wooded vs open) and elevation above ground; these are
governed by publication ASCE 7 (American Society of Civil Engineers Minimum Design Loads for
Buildings and Other Structures). Wind speeds of 115 psf are used to calculate wind pressures against the
glass, which generally vary from 17 psf (2
nd
story in wooded area) to 35 psf (30 stories tall in open
terrain). The wind speeds required to match the stresses created by the 800# point load are 192 mph
for the 42” tall panel and 215 mph for the 36” tall panel; these are only seen in a Category 5 hurricane or
a tornado. Therefore, the 800# horizontal point load is the worst-case scenario for the panels. Note:
panel design in “high wind” regions such as the coastal Southeast US are designed to resist flying debris
and are subject to different loading requirements. Calculation methods to arrive at these values include
computer modeling using finite element analysis; criteria specific to Clear View’s panels and support
configuration were used.
Hercules Glass Testing
Testing was performed on the Hercules Glass panel by Clear View’s glass supplier, to simulate the forces
created by 800# horizontal and vertical point loads on the panel (loads are not required to be
simultaneous). The vertical load test is straightforward and is shown in photo 1. Note: the intent was to
load the panel to failure; however, the testers ran out of sandbags at 2,520 pounds, without failure.
Given the difficulty of pushing an 800# load horizontally against the panel, a test rig was set up that
supports the panel on its side and places sandbags vertically on the panel. The panel is supported 28”
from the top of panel (creating a 28” cantilever), with a heavy counterweight holding down the bottom
of the panel mounted in its spigots. Sandbags were placed at the top edge of the panel until failure. See
Diagram 1 and photo 2. The panel failed after one minute with 820 pounds loaded on its edge, which is
equivalent to 547 pounds for a 42” tall panel. Due to the laminate construction of the panels (similar to
a vehicle windshield), the panel broke into small pieces that were retained within the panel, preventing