Three days after hosting his 18th birthday party, the family of Sydney apprentice Christopher Cassaniti are planning his funeral.
The formworker was crushed to death on Monday after scaffolding, 15 to 17 metres in height, collapsed on him and a co-worker at a construction site in Macquarie Park.
Mr Cassaniti initially couldn't be accessed by paramedics and was pronounced dead at the scene a few hours after the incident.
His mother had days earlier sung the praises of her "compassionate and shy, yet strong and forever helpful" son when he turned 18 on Wednesday and held a birthday party on Saturday.
"We wish you all the best that the world can dish out and May God be forever in your heart and bless you with much joy, happiness and most importantly health," she had posted to Facebook.
On Monday evening, friends of the former St Patrick's College student posted tributes in memoriam.
"You were a fantastic bloke and had a heart of gold," Benjamin Betros said.
"You have been my friend since the first day of kindergarten .. words can't express how much this hurts. You were full of positivity, always smiling, always seeing the best in everyone," Bella Mineo said.
Mr Cassaniti's colleague, a 39-year-old man, suffered critical injuries to his lower body and was taken to Royal North Shore Hospital.
SafeWork NSW and police are now trying to work out why the scaffolding at the Lachlan's Line apartment complex collapsed.
"It is expected that the investigation could take some time, while SafeWork inspectors work through the complexities of the incident," a spokeswoman said.
A spokesman for construction company Ganellen expressed sympathy to the family, colleagues and friends of the young man.
"The welfare of our thousands of employees and subcontractors has always been a priority for Ganellen so this is devastating news," he said in a statement,
The fatal incident angered the construction union CFMEU, a spokesman said.
"Such tragedy should not occur," CFMEU construction and general secretary Darren Greenfield said in a Facebook post.