City Department of Buildings officials inspected the structure after firefighters battled an hour to put out the blaze sparked by the noontime explosion, and issued a full-vacate order based on their findings.
DOB investigators said they found 16 instances of illegally converted apartments, gas pipes and gates on apartments.
Some of the secondary exits from the second to fifth floors were blocked, and the building lacked proper smoke and carbon monoxide detectors. Officials also found exposed electrical wiring and paint violations in their inspection.
Building owner Mary Shiu was issued two Environmental Control Board summonses for violations found Thursday.
Shiu was also cited four years ago for two violations and issued a full-vacate order for failure to maintain the property.
Inspectors in 2009 found a separation between the floor and the wall on the ground level of the building that "posed a danger of collapse," DOB records show. Shiu was also cited for a lack of fire-stopping material.
The vacate order rescinded in March 2009 after Shiu paid a $2,000 fee and both violations were resolved. There were no other open violations at the time of the explosion.
Eight civilians and five firefighters were treated for smoke inhalation and burns Thursday, and two were in serious condition at New York-Presbyterian Hospital.
Officials had not officially determined the cause of the explosion or collapse, but said the building was structurally sound. Initial theories suggested improperly used "bug bombs" may have exploded and blown out a wall, but authorities were not ruling out a gas leak.