Pieces of glass the size of sugar cubes were scattered across the sidewalk outside a downtown condominium building Monday afternoon after a panel of balcony glass shattered and fell from the 31st floor, injuring one woman.
Police said they received the report that the glass had fallen from the south tower of the Murano Condominiums development – located at the northeast corner of Bay and Grenville Streets – just before noon.
The woman got stitches for a cut on her wrist at hospital, said Toronto Police Service spokeswoman Wendy Drummond.
Lanterra Developments, which developed the condominium buildings, did not return calls Monday.
Mike D'Agnillo, vice-president of Toro Aluminum Railings, the company contracted by Lanterra to do the balcony guard rails on the development's south tower, said one panel of glass broke and fell in little pieces from the tower Monday.
Noting that there are about 3,000 pieces of balcony glass on the building, Mr. D'Agnillo said that the guard rails were completed more than two years ago and that it has been more than a year since "other breakage" occurred.
There have been four incidents involving falling glass at the north tower since December, 2010, said Jim Laughlin, deputy chief building official for the city of Toronto. After the third incident, on July 21, he issued an order requiring Lanterra to replace all the glass balcony panels on the building.
"I wasn't prepared to see what would happen next," he said Monday.
Then, on Aug. 1, it happened again.
Mr. Laughlin has issued an order for Lanterra to hire an engineer to analyze the problem and submit a report to the city, and to establish overhead protection on the Bay Street and Grenville Street sides. Protection has already been set up on the Grosvenor Street side because of the earlier incidents.
According to Doug Perovic, a professor of materials science and engineering at the University of Toronto, there are two possible explanations for glass repeatedly falling from the buildings. The first, he said, is a raw material problem and the second is an installation problem.
"In glass, there's all kinds of different impurities, but there's one in particular that's a real potential problem and that's called nickel sulphide," explained Dr. Perovic. "There are little particulates of a combination of nickel and sulphur which are ... sort of frozen in when they finally solidify the glass and the problem with them is that they grow over time."
"These little particulates," he continued, "are expanding in the glass, causing stress and then they produce enough stress that the glass just can't stand that – it's a brittle material – and then it just essentially explodes."
The other possible scenario, Dr. Perovic said, has to do with the hot days this summer and if the glass was too tightly fastened.
"As the glass heats up, it wants to expand and, if you're holding it in on all sides too tightly, you're not giving enough room to expand into, then the stress builds up around the edges and then that can cause it to shatter as well."
On Saturday, a pane of glass fell from the balcony of another Lanterra building, at 1 Bedford Rd. On Monday, the entrance to that building was taped off and a yellow city of Toronto "Order to Remedy Unsafe Building" notice was posted to one of the front doors.
With a report from James Bradshaw