Developers of the 20-story Exelon Building at Harbor Point still haven’t determined why a glass window shattered and fell last year, injuring two people, but they plan to build a protective canopy around the perimeter sidewalk in case there are more problems.
Beatty Development Group said work would begin in June on the 7-foot-wide cover, replacing scaffolding in place since glass pieces fell last October. The canopy should be completed by this October.
The company said at the time of the accident that a total of six windows in the building had failed, and imperfections have been found on dozens more. Beatty has replaced 66 windows.
Beatty didn’t say if more problems have been found since last fall. The building has 7,500 panels of tempered glass.
Officials said the problems likely were caused by “nickel sulfide inclusion,” which happens when trace elements form tiny balls during the glass manufacturing process and cause what seems like a spontaneous break in the tempered glass over time.
The Exelon building opened in 2016 and is anchored by the Exelon Corp.’s regional offices and the headquarters of its Constellation business unit. Exelon employs 1,500 people in the building. The tower also includes retail space on the ground floor, 103 residences and a 750-car garage.
Harbor Point, a former industrial property jutting into the Inner Harbor, is being developed into a 27-acre mixed-use project.
It’s not known how often windows fail in buildings across the country, but there have been media accounts in several cities in recent years. Windows are not typically inspected by local governments, and they don’t normally respond when one fails. Testing isn’t required by developers, either, though many hire firms anyway.
There are industry standards governing windows. They generally call for hardened glass that is stronger than regular glass and glass that is tempered to shatter into tiny pieces rather than fall as shards that can be far more dangerous.
Experts have said that there are more window failures now than decades ago, largely because lower-quality or counterfeit products made overseas have been found on the U.S. market. Beatty has said the Exelon windows were American made.
Some windows made according to specifications still can fail because tiny imperfections can be hard to spot before a window breaks, experts have said.