Drexel University Associate Professor Robert Brehm said there is no easy answer to the question of the day: Was the building properly secured by demolition crews?
"When you're demolishing an old building, it's not a science," said Brehm, who teaches in Drexel's department of civil, architectural and environmental engineering.
"We're not going in there and doing precision cutting," Brehm added. "And when you have old buildings, it's hard to predict exactly how they are going to respond."
Brehm, who has more than 40 years experience in construction, said if he was working on this demolition project, he would look to the close proximity of other buildings.
He said it appears the mason wall of the four-story building fell outward, toward the thrift store, as opposed to inward into the demolition, and that led to the collapse.
"It's coming down one way or the other," he said. "It's either going to fall to the left or fall to the right. I don't know know what caused it to fall outward as opposed to inward, but you're starting with a very unstable structure."
If he was investigating this project, he said the first question he would ask is, "What were the protocols and procedures?"
"I would have made sure I secured the site," he said. "And what does that mean? That means taking people out of harm's way."
He said what happened he's sure wasn't expected, "but it's predictable."
The collapsed building at 2136-38 Market Street was owned by Richard Basciano.
The demolition was done by Griffin Campbell Construction, owned by Griffin T. Campbell. A call made to the Griffin home was not returned. Non-union workers were used on the project, officials said.