Sign Falls, Kills Man
On January 23, a massive storm that spawned 60 mph winds ravaged the East Coast and caused major damage and injury in several cities. One tragic resulting report was the death of a 60-year-old man who Philadelphia’s Channel 10 (NBC) reported was killed by a falling sign: “A man was struck and killed by a sign that was blown off a wall by the wind Monday afternoon in the Hunting Park section of Philadelphia, according to police.” However, my next-day conversation with the City of Philadelphia’s Karen Guss, the director of communication for licensing and inspections, said the medical examiner reported that even though the sign had dislodged and fallen on the poor soul, their autopsy revealed that a heart attack had killed him, not the sign.
Still, the wind blew the wall-mounted cabinet sign down. I enlarged and examined the news photos to see excessive mildew and mold on the sign back, which caused me to believe it was installed some time ago. In my opinion, installation component fatigue aggravated by the strong winds led to the failure.
Philadelphia news agencies also reported that parts of a Hahnemann University Hospital “Independence Starts Here” mural had broken loose and fallen in the windstorm and damaged cars in the parking lot below. As the accompanying photo shows, the painted-fabric mural, installed in 5 x 5-ft. sections, covered the exterior walls of three building façades. Guss said the city’s inspectors had examined the mounting failure and determined the building’s exterior insulation and finish systems’ (EIFS) cladding had separated from the structural walls and carried part of the mural earthward.
The Building Science Corp. (West-ford, MA) says EIFS is a “general class of non-load bearing building cladding systems that provides exterior walls with an insulated, water-resistant, finished surface in an integrated composite material system.” I must add that different types and brands exist. The face-sealed types, popular in ’80s construction, are least desirable for most applications, because they absorb moisture which loosens the binding. The newer, drained, water-resistant EIFSs (that prevent water build up on the second surface) are preferred.
The 1,200-sq.-ft., seven-story mural, created by artist Donald Gensler, was installed by Mural Arts Philadelphia, an agency that has beautified much of the city by sponsoring and often installing large and colorful murals. Jane Golven, the organization’s executive director, said their organization, which leads the largest public art program in the US, is a joint city and private nonprofit organization that works in unison with the city and its communities.
The “Independence Starts Here” mural began with an outline projected onto panels of QST Industries’ Poly-tab 20r fabric, sometimes called “parachute cloth,” which was then fill-painted by members of local disability advocacy organizations. Amy Johnston, an executive assistant to Golven, described the install process as the crew bonding the painted parachute cloth to the existing building cladding with gel, then overcoating it with clear acrylic when dry.
Regarding safety, Golven said all its Mural Arts’ installers are OSHA certified and comply with their organization’s procedural handbook. In this case, the failure appears to point to the EIFS cladding, which was soaked by the rain and pummeled by the high winds.
Obviously, then, strong winds were behind both sign failures. In “Engineering Sign Structures” (published by ST Books and available on Amazon) civil engineer Benjamin Jones says weather conditions produce two types of stress loads: wind from all directions and the weight of snow and ice. Other hazards are natural phenomena, earthquakes, floods or impact from an unplanned source. Perhaps his most important statement is, “We must visualize how the forces produced by these loads will be transferred along the chain of interconnected components.”
Wind force can cause continuous shuddering that will weaken mounting systems. Think of continuously bending a wire coat hanger to break it.
The National Severe Storms Laboratory (Norman, OK) describes such damaging winds as “straight-line” winds and says most ground-level winds (thunderstorm winds, not tornado or hurricane) are caused by an outflow generated by a thunder-storm downdraft. Its website also says severe thunderstorm winds – which can produce a damage path that extends for hundreds of miles – account for half of all severe wind reports in the lower 48 states and cause more damage than tornadoes.
Obviously, installation methods and hardware are critical to sign safety. Old signs need safety inspections and their mounting façades more closely diagnosed. Further, sign fabricators must recognize that their installed products may face more stress than originally imagined, and perhaps for a longer time, as well.