The royal commission suggested the charity group did not qualify as a charity at all, but was used to generate profits for the union. It also questioned donations from the Tradies group of clubs, which give money to the union's charity arm as part of their community contributions.

But Mr Hall said the charity had been set up to help construction workers, whose industry had the highest rates of workplace fatalities, suicide and family breakups in the country and among the highest rates of drug and alcohol abuse.

"The reason we started was because no one was there for construction workers. When I started it was the union – we'd turn up with no training no skills and try to work out what was happening," he said. "The union put me through a social work degree because of that."

The charity, Construction Charitable Works, had helped workers and families in every serious construction accident in Canberra in recent years – including the 2010 Barton Highway bridge collapse from which concreter Toby Turnbull still has pain, and the 2012 accident on the Nishi building where Jason Bush almost died after falling down a lift shaft.

Both men are featured in videos on the Construction Charitable Works website, talking about the rehabilitation, psychological help and retraining they receive.

Jason's father, Graham Bush, said this week his family couldn't have got through the past three years without the help of the group, which had given his son an iPad, bought him a bed that could accommodate his broken back, paid for weekly counselling, and given him work teaching others about workplace safety. He was still unable to work full time and was on pain killers.

"They ring up and say can we catch up with Jason, how's he going? I'm not a union person, I'm not supporting them, but what they did for us, we wouldn't have been able to do it without them, I know that," Mr Bush said.

In a video made in 2015, Work Safety Commissioner Mark McCabe also gives the organisation a tick of approval, saying the industry had become increasingly dependent on such organisations to help people with mental illness and workplace injuries.

Vince Ball, of the ACT Regional Building and Construction Industry Training Council, endorses the group, saying its success is not highlighted enough.

But the royal commission said the donations from the Tradies to the charity arm might not have been "genuine contributions to a charitable organisation but disguised contributions". The $715,000 given in 2013 and 2014 was declared as used for "drug and alcohol training", but nothing like the amount had been spent, the commission found, also accusing the charity of paying a vastly inflated "management fee" to the union's training arm, which then flowed back to the union.

It said more than 80 per cent of the charity's spending went to the training arm, with a "relatively modest" $10,000 a year going to counselling and some to reserve emergency accommodation.

Mr Hall said he would cop most of the royal commission's criticisms since they were "just horseshit", but he would defend the work of the charitable group. The money it gave to the union's training arm was used to train apprentices in health and safety, the dangers of drugs and alcohol in the workplace, and suicide prevention.

Acting chief minister Simon Corbell declined to comment on the royal commission's findings, beyond saying the government would consider them. Tradies chief executive Rob Docker would not comment.

The Australian Charities and Not-for-profits Commission said it could not confirm or comment on investigations into registered charities. Any concerns raised were considered by the commission and if plausible and substantial were investigated, a spokesman said. Other measures included "education, guidance and support" to help charities meet their obligations.

The federal police said it would evaluate the royal commission's findings in relation to Creative Safety Initiatives (connected to the training arm) and Construction Charitable Works, with alleged criminal offences including tax related offences punishable by up to one year's jail.
"The AFP will evaluate the case study within the report for criminal offences within both the Taxation Administration Act and Criminal Code," a spokesman said.