Officials: Collapse likely caused by insufficient bracing
NASHUA – Lack of sufficient bracing appears have caused the collapse of roof trusses being installed at a construction site at 33 Pine St. in Nashua last month, according to investigators working for the city.
"Under our preliminary investigation, our department is focusing on the lateral and diagonal bracing and the permanent bracing that should have been in place," said William McKinney, the city’s building safety department manager. "At the stage it was in, there should have been more permanent bracing. It appears it was not installed."
A crane was being used by workers Jan. 27 when a series of prefabricated roof trusses fell into the shell of what was planned as a 200-seat auditorium. The building was going through extensive renovations to become part of the Crossway Christian Church.
The church has buildings in both Nashua and Milford.
"It was a catastrophic failure of the truss system that was being erected," McKinney said at the scene the day it collapsed.
The building, a former Asian market near the intersection with Central Street and across from the Bronstein Apartment complex, was 106 feet long by 70 feet wide. About 30 large trusses that had been temporarily joined together as part of a final assembly process had collapsed one after another
Since the incident, investigators from the Occupational Safety and Health Administration were also gathering evidence and trying to determine a cause. McKinney said his department would compare their preliminary findings with those of OSHA and other engineers involved before issuing a final report.
McKinney said there was some temporary bracing installed on the 37 trusses that had been installed so far on the building. He said procedurally when workers have placed 6 trusses, "more permanent and diagonal bracing needs to start. It doesn’t appear all had been in place," he said.
"The systems are complicated," McKinney said. "If you don’t follow the instructions fully, this is exactly what happens. We see it all the time when all of the bracing doesn’t get installed."
In this case, he said "thankfully no one was injured; or worse. When working with this type of a system, the plans are there for a reason."
McKinney said the final report could perhaps be released this week.
Don Himsel can be reached at 594-1249, firstname.lastname@example.org or @Telegraph_DonH.