Dennis Berg, a man with a severe intellectual disability and mental health issues, was arrested in May 2019, and charged with multiple counts of arson.

Of the 10 cars he set fire to, nine of them were on the street, and all were within an eight-block radius of his home.

He has been in custody since his arrest, and has served 447 days of pre-sentence detention.

On Tuesday, Judge Duncan Allen convicted Berg in the County Court and sentenced him to 15 months prison, to be followed by an intensive three-year community corrections order.

Judge Allen noted the significant effect of Berg's offending on the victims.

"The vehicles valued at various amounts, ranging from $3000 up to $65,000, and each was destroyed by the fires," he told the court.

"In each case, the victims suffered significantly - not only financial loss and inconvenience, but significant distress and emotional and psychological harm.

"The impact on the victims who provided victim impact statements was clearly significant, and in some cases has had a lasting effect by way of lasting insecurity, panic, fear, and other such psychological impacts."

However, Judge Allen also noted numerous expert assessments had concluded Berg was substantially intellectually disabled.

"You suffer a significant intellectual disability which affects your executive functions, resulting in you displaying highly inflexible and preservative thinking together with an extremely limited understanding of social interaction," Judge Allen said, noting the reports added Berg was not able to plan logically or anticipate the consequences of his behaviour.

He also detailed the severe difficulties Berg has faced while in custody, including being moved to protective and medical care instead of being able to engage with support services.

"Your counsel pointed to the fact that expert reports all point in one way or another to the obvious need for prolonged, intensive treatment, supervision, and support," Judge Allen said.

"If the community is to be protected from you by way of you being rehabilitated, I have no doubt that the longer you spend in jail, the graver the danger that upon your release, there would be a significant risk of you relapsing into criminal conduct.

"I have no doubt that the best way to achieve the protection of the community by way of your rehabilitation, whilst at the same time punishing you, is to put in place a program focused on that intensive treatment, supervision, and support."

Berg will be required to complete a number of programs and submit to judicial monitoring every three months, and was assigned a case worker to ensure he meets appointments and to apply for NDIS support.

Judge Allen declined to make a compensation order for the victims, stating it would be overly burdensome on Berg, who would likely never have the capacity to pay it.

"Whilst I understand that each of the victims is entitled to an order, it would be entirely pyrrhic, and on balance of evidence, inappropriate to make such an order in the interest of justice," he said.

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