Volume 50, Issue 5 - May 2015

NewsAnalysis:SKYLIGHTS

All Skylights are Not Equal; ASTM Works to Establish Human Impact Test Method

This winter, there was a wave of reported skylight falls—most of them in New England—largely due to a lack of safety precaution measures during snow removal on roofs.

Most reports didn’t specify the skylight material, though the few that did noted the skylights were plastic or fiberglass—not commercial applications of laminated glass. At press time, a representative of the Occupational Safety and Health Administration, which investigated many of the accidents, hadn’t responded to USGlass magazine’s inquiry regarding the type of skylights involved in the incidents.

“These falls are not a glazing problem, but a risk-exposure issue,” says John Westerfield, AAMA skylight fall protection task group chair. “Plastic skylights are used primarily on low-sloped and flat roofs—the roof types where workers walk. Some of these incidents appear to be a roof-access safety concern, as well.”

Those factors aside, ASTM International is working to establish a new test method for human impact on commercial skylights. According to the ASTM scope, it will “develop a standard for the purpose of establishing fall-resistance criteria and a test method that will simulate falls of persons onto unit skylights and related products installed onto low-slope roofs.”

It continues, “A consensus based upon standard practices, standard impact test methods, materials commonly used, and risk assessment will be the basis for developing this human fall resistance specification and test method. Exploration of meaningful certification and/or labeling will be examined.”

According to Urmilla Sowell, technical director for the Glass Association of North America (GANA), for testing, the working group decided on an impact load of 300 pounds at a height of three feet with a tapered sand bag. Currently, the group is discussing weatherability/durability issues.

The testing isn’t limited to a specific type of skylight, according to Chris Magnuson, first vice president of AAMA’s skylight/sloped glazing council and a member of the AAMA skylight fall protection task group. “All unit skylights, regardless of glazing material, are subjected to the same impact test and performance specification,” he says.

“The only difference in proposed criteria is in the ‘Durability of Materials’ section, which logically requires different weathering specification requirements for each material type—including to ensure external metal screens would resist rusting,” adds Westerfield. “All products are subjected to the same drop-bag impact test criteria.”

Industry members, including George Petzen of Linel Architectural Glass and Metal Solutions, point out that commercial laminated glass applications typically can withstand a higher load than the plastic glazing skylights that are often involved in such incidents. He stresses that all skylights aren’t created equal, something that can certainly be proven through impact testing.

“In my world, in 30-some-odd years of doing glass skylights, I’ve only seen or heard of two instances of people going through them,” says Petzen. “And they were intentional and from an extraordinary height—as in 10 stories above.”

GANA had previously addressed the concern in 2012 in its Glass Informational Bulletin titled “Skylights and Sloped Glazing are Not Walking Surfaces.”

The bulletin reads, in part, “Installation and maintenance of skylights and sloped glazing systems require special consideration to minimize the potential for serious injury or death. While architectural flat glass can be designed and engineered for use as a walking surface, glass typically used in skylights and other sloped glazing applications is rarely designed to support the concentrated weight of live loads such as a human standing or walking on the glass or temporary equipment or structures used in installation, cleaning or maintenance.”


ASTM International is working on a test method for human impact on commercial skylights.



—Nick St. Denis



USG
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