A Wellington building used to film scenes in the Lord of the Rings trilogy and King Kong which was damaged by fire last week, did not have automatic smoke detectors.
The blaze at the building used by Sir Peter Jackson's Weta Workshop in Rongotai Road in the suburb of Kilbirnie happened last Friday.
The property is owned by Portsmouth Miniatures Studio and was used by Weta Workshop to film the miniatures scenes for the movies.
At the height of the fire, a thick black column of smoke could be seen around Wellington and from the Hutt Valley.
Fire safety officer Stuart Law says initial findings show it is likely the fire was caused by batteries being charged.
He says there was no sprinkler system, and no automatic smoke detectors in the building, only a manual smoke alarm.
Mr Law says every industry should install automatic detectors.