Monday, April 8, 2013

A Costly Architectural Oversight


The John Hancock Centre stands as the tallest building in Boston USA however after its completion in 1976, it became the subject of severe media criticism, when it became evident that building liked to drop windows onto the pavement below it.

The windows in question weren't of the small variety, they were as one pundit described it, 5-by-12-foot, 500-pound slabs of aerial death. Sadly it wasn't just a few of them, hundreds and hundreds of windows went hurtling to the streets below. The problem got so bad that whenever winds exceeded 45 miles an hour, police would close off the entire area around the building for public safety.

During one windstorm in January of 1973, over 60 windows were knocked loose from the building's facade. By April of that year, more than an acre of the building's exterior was covered in plywood boards where windows once stood. They initially painted the plywood black, however this effort to hide the severity of the situation proved wholly ineffective.

A team of engineers, architects and builders all got together to work on a solution to the problem, but their findings were initially kept secret. An independent laboratory eventually confirmed that it was due to oscillations and repeated thermal stresses caused by the expansion and contraction of the air between the inner and outer glass panels which formed each window. The bonding between the inner glass, reflective material, and outer glass was so stiff that it was transmitting the force to the outer glass (instead of absorbing it), causing the glass to fail

In the end, the issue was resolved by replacing all 10344 windows of the 60 story skyscraper at a cost of $7 million, an astronomical amount of money, by 1976 standards.

Source: and

Ernest Roper
Membership Services Manager


1 comment:

Master builder said...

7 million is an astronomical amount of money by the standards of 1976.Its value was high than it is today.Master builder