The inquest, the longest running and largest in the Republic of Ireland’s history, was held at Dublin City Coroner’s Court.
It sat for 122 days and heard testimony from 373 witnesses.
The fire was first seen outside the building between 01:20 and 01:40 local time. Gardaí (Irish police) arrived at 01:50.
The jury found the height of the nightclub ceiling and materials in the bar, including carpet tiles on the wall, were found to have contributed to the blaze.
Lack of visibility, lack of knowledge of the building and thick, toxic smoke were found to have made it more difficult for people to leave.
In addition, the heat of the fire, speed of its spread, failure of the emergency lighting system and lack of preparedness of staff played a part.
Emergency exits were locked, chained or otherwise obstructed and victims were impeded in their ability to exit.
The jury found that 42 people died on the premises.