A balcony deck was supported by a rotted bearer when it collapsed as guests gathered for a selfie at a Melbourne Christmas party, killing two people, a coroner has heard.
Croydon woman Cheryl Taylor, 59, and Reservoir woman Sarah Kajoba, 37, died when the balcony gave way during a Tupperware workers' Christmas party at a private rental home in Doncaster East on December 16, 2017.
About 37 people were at the party when guests gathered on the 40-square metre timber deck to exchange gifts and take a "selfie", counsel assisting the coroner, Leading Senior Constable Tracey Ramsey, told Tuesday's directions hearing.
However, as they shuffled into position, a 6.1 metre wide and 2.7 metre long section of deck collapsed without warning.
Guests reported a loud cracking noise and the deck "going totally from under their feet, like it collapsed in on itself".
Ms Taylor and Ms Kajoba were believed to be sitting on lounge chairs in a central part of the deck when it fell onto a concrete paved area underneath.
Ms Taylor died from suffocation while Ms Kajoba suffered multiple injuries.
"It was a tragedy, obviously, and they were unlucky to be where they were," coroner Paresa Spanos said.
Twenty-eight people fell, while others, including a lady tending to her baby at the opposite end of the deck, were unaffected.
The deck was holding hundreds of kilograms of furniture and other items, including a fridge weighing 123kg when empty, a BBQ and gas bottle weighing 82kg and a 50kg pizza oven.
Three building experts found the collapse was caused by the failed Oregon bearer and the weight carried, Leading Sen Const Ramsey said.
The bearer was weathered, rotted and had pre-existing cracking. It was also insufficient in size for the load it was holding and ultimately failed under a concentrated weight.
Municipal building surveyor Russell Mills believed the deck was not built to original approved plans and was larger than stipulated. The floor joists also ran in the opposite direction as planned.
The inquest will explore whether an addition to the decking also affected its structural integrity, if it complied with the building code at that time and who was responsible for its maintenance.
Ms Spanos said it was not necessary for party goers to testify at the inquest, likely to start early next year.
The injured are planning to seek compensation and lawyer Lily Boskovski, representing six of the 17 people injured, says the psychological scars cannot be underestimated.
"They've witnessed their coworkers die. I can't even imagine how it might feel to one minute be enjoying a party and then saving yourself from dying," she told AAP.
She said the inquest would be critical to dissect what happened and what parties were involved in allowing the balcony to collapse.
