Kashim Ali, the president of the Council for the Regulation of Engineering in Nigeria, added that the building did not have the correct permit.
Work began in 2013 and state authorities issued several "Stop Work" orders on the structure, the report said.
The engineering investigation also revealed that the building was located on a slope at a sharp corner which added to the danger. Many of the buildings columns and beams had inadequate stirrups. Stirrups help prevent support beams from buckling.
Ali urged the engineers involved in the project to surrender themselves to the authorities.
"Failure is not unusual. This is because structures can fail even anywhere in the world," Ali said.
"Failure is also a way of learning but the failure must come in a structured way so that it does not kill people."
The roof at the Reigners Bible Church International in the city of Uyo gave way during a busy service on December 10.
At least 160 people died, though the state government claims only 27 were killed.