A judge has told a Christchurch man, who set his father's house alight after abusing methamphetamine, that he was lucky to be alive.

Bradley Schenkel, 28, was convicted of arson and sentenced to nine months home detention at Christchurch District Court this afternoon.

He had set his father's house on fire in May 20, after the combined effects of drugs, insomnia and health issues took its toll, and he ended up believing the house was possessed by "evil energy".

Lawyer Stephen Hembrow said that in the weeks leading up to the offence, the defendant had lost his job as a carpenter.

He said that had removed the routine from his life, and he had experienced steep ups and downs as a result. In the five days running up to the fire, he also hadn't slept.

The lawyer said that Schenkel biked to his father's house, and saw his wallet lying on the counter. As his father was never without it, the defendant thought his father was dead.

"His one objective for living was the love of his father. With his father gone he didn't see any point anymore", Hembrow said.

Schenkel then went to the shed, grabbed a litre of petrol, poured it around the inside of house, and after turning on the LPG and kitchen hobs, he set it ablaze.

Hembrow said Schenkel was "deeply ashamed". He also said the defendant had told him that he was "just so pissed off at myself".

He asked Judge Raoul Neave to consider a sentence of home detention, and that an address in Motueka had been approved by probation.

Hembrow said that Schenkel had shown "genuine remorse" during an earlier restorative justice conference between the defendant and his father.

Many of Schenkel's family were in court and repeatedly broke down in tears during the sentencing.

Schenkel looked down at the floor throughout, and almost broke down himself when the judge delivered his final verdict.

Judge Neave said the defendant was lucky he was still alive after starting the fire.

He said that Schenkel had been suffering from health issues and the effects of methamphetamine use at the time of his offending.

He also said that the offending had been in part driven by an "irrational fear that the people who were out to get you had killed your father".

The judge began with a starting sentence of 3 years, which was in line with the recommendation in the pre-sentence report.

He reduced the sentence by six months because of the serious issues which the defendant had been suffering from. He then cut it by a further four months for the remorse he had shown during the restorative justice process.

With a full credit of 25 per cent for his guilty plea, the judge was left with a final sentence of 19.5 months. He converted that to a nine month home detention sentence.

However he said that there was no element of deterrent needed to be included as part of the sentence. That was because "the loss to your father was total. The memories and memorabilia can never be replaced".