The safety of a wall that collapsed and killed three people in Melbourne six years ago was the responsibility of site owner Grocon, a coroner says.

Siblings Bridget and Alexander Jones and Frenchwoman Marie-Faith Fiawoo died after the freestanding brick wall fell onto Swanston Street in Carlton on March 28, 2013.

Coroner Sara Hinchey on Thursday said in her findings the onus to ensure the wall’s structural integrity rested with Grocon, which owned the site at that time.

In October 2011, Grocon engaged Aussie Signs to put signage on the wall. Aussie Signs subcontracted the work to JT Hire, which in turn subcontracted the work to Paramount Signs.

The coroner also said the timber structure was not legally exempt from a permit.

She noted if a building permit was sought, an engineer would have needed to prepare drawings and computations, which would have confirmed if the building work was structurally sound.

“In particular, whether the timber structure would have been able to be adequately supported by the existing masonry wall and timber paling, ” Ms Hinchey said.

The coroner said changes to laws and company policies of the entities involved had changed adequately after the incident, to prevent a repeat.

Building laws changed in 2016. Now duties are imposed on land owners and builders to ensure a building permit is in force and work is carried out according to law.

In 2016, Aussie Signs Pty Ltd was fined $250,000 in the County Court after pleading guilty to failing to ensure people were not exposed to risk.

Grocon owned the site and commissioned the construction of the advertising cladding.

The 3.2-metre-high hoarding was up to 70 centimetres taller than the brick wall it was attached to.

The subsidiary of construction giant Grocon was also fined $250,000 in 2014, after pleading guilty to failing to provide a safe workplace.

There were strong winds on the day of the fatal collapse, though the exact strength at the site was unknown.

A subcontractor hired to attach cladding to the wall, Jonathon Westmoreland, was fined $7500 in 2015 after being found guilty of performing works without a building permit.

The coronial investigation focused on opportunities for prevention, policy and law changes.

-AAP