Last week, when a window detached from 555 California St. due to high winds and shards of glass crashed to the ground, building inspection officials painted the event as an unusual incident that didn’t reflect the overall state of Downtown San Francisco high-rises. 

But a number of similar window cracks and breakages that occurred as buildings were battered by weather conditions on Tuesday have building inspectors singing a bit of a different tune. 

“When it comes to potential building code changes, that’s something we’re currently looking at,” said Department of Building Inspection spokesperson Patrick Hannan. 

He said the building department is also weighing other proactive measures meant to ensure the safety of high-rise windows similar to the department’s facade inspection program, which requires that building facades be regularly inspected by licensed architects or engineers with reports submitted to the department.

“Do we need to have a proactive program where people are checking the glass? That’s part of what we’re discussing,” Hannan said. 

There were four high-rises that experienced window breakages or cracks on Tuesday that varied in severity.

• At 50 California St., one window was broken between the 13th and 14th floors. The window was secured and a site visit was conducted to confirm. 
• At 301 Mission St., also known as Millennium Tower, one swing-open type window was broken on the 49th floor. That window has been removed and the opening was boarded up. 
• At 350 Mission St., also known as Salesforce East a line of 19 windows were broken on every floor between 11 and 30. 
• At 1400 Mission St., a building inspection staffer noticed and reported that a fifth-floor window that was damaged.

Hannan said the initial inspection of windows prior to the opening of a building focuses on two main elements: the strength of the glass and how it is attached to the building. Tests include engineering calculations based on location and wind tunnel analysis that are reported to the building department and are reviewed by the department’s structural engineers.

Supervisor Aaron Peskin, who represents a swath of Downtown, has called for a hearing on the the department's ability to deal with increasing incidents of storm damage to tall buildings, including the issue of falling windows.