A man was injured Monday evening when the reinforced concrete floor of a stair landing in his Boulder apartment building collapsed.

The man fell between 8 and 10 feet.

The property manager said metal fatigue appears to have contributed to the collapse, which he said came as a complete surprise to his staff.

"We're very proactive in our maintenance," said Jim Cuckler, general manager of Newcastle Property Management, which has been responsible for the building for the last 20 years. "It's a very unusual event. We're going to get to the bottom of it."

The building at 2898 Aurora Ave. is part of the Cavalier Apartments near Aurora Avenue and 30th Street. The city's chief building official toured the apartment building with the property manager after the incident, and one other stairwell was blocked off as a precautionary measure.

City spokeswoman Jody Jacobson said all rental properties have a safety inspection performed by a third party as part of obtaining a rental license. Rental licenses must be renewed every four years, and the Cavalier Apartments successfully renewed last year.

Police and firefighters responded to a report of a fall from the collapsed landing around 6 p.m. Monday. The victim, a resident of the building, was taken to Boulder Community Hospital, but neither police nor firefighters had information Tuesday about the extent of his injuries, except to say that they were not life-threatening.

The collapse left a 4-foot-square hole in one stair landing.

Jacobson said the steel deck holding up the concrete had "rotted," and one other stairway, out of four stairways in the complex, appears to have similar issues.

Second-floor residents still have access to their apartments via the other staircases.

Jacobson said the property owner will need to hire an engineer to address the structural issues.

Joey Bowers, a University of Colorado graduate student who has lived at the building for two years, said there have been other problems at the building -- including the time his ceiling collapsed due to a water leak -- but nothing of this magnitude.

"The building is not, I don't think, in great shape," he said. "It does make me feel less safe."

Contact Camera Staff Writer Erica Meltzer at 303-473-1355 or meltzere@dailycamera.com.