A Perth businessman has been jailed for more than seven years for an attempted $20 million insurance scam that involved the deliberate burning down of a Welshpool factory.

Key points: Hossean Pourzand's property was the former WA headquarters of Bunnings

Hossean Pourzand's property was the former WA headquarters of Bunnings Citronella-soaked cords were used to start the fire by one of his associates

Citronella-soaked cords were used to start the fire by one of his associates The property tycoon pleaded guilty and has been jailed until at least 2023

Hossean Pourzand, 65, owned the Pilbara Street property that was extensively damaged in March 2017 when one of his associates, whose identity is suppressed, disguised himself, turned off the electricity to the building and used citronella-soaked cords to start the fire.

Emergency crews arrived about seven minutes later but it took them six hours to contain the blaze.

The premises was the former WA headquarters of the Bunnings hardware chain, which had vacated the warehouse the month before.

The Supreme Court was told Pourzand claimed he did not have the money to fund a refit of the warehouse, so came up with the plan, with his associate, to set it on fire and then claim the insurance.

He made that claim the next day and the court heard if he had been successful, he would have received somewhere between $8.5 million and $19.9 million.

Fire crews took six hours to contain the massive blaze at the former Bunnings HQ. ( Supplied: Night News )

His plan began to unravel in May after police publicly released an image taken from CCTV footage of a man they said they would like to speak to about the fire.

The image was of Pourzand's associate.

Pourzand then contacted detectives to identify him, but maintained he had nothing to do with the fire.

'Tonight is the night'

The associate was arrested and it was discovered he had made secret recordings of his meetings with Pourzand in which they had discussed the arson plan.

The conversations included Pourzand telling the associate what clothing to wear, how he should conceal his identity and saying "tonight is the night".

Bunnings had vacated the warehouse, its former WA headquarters, a month before the fire. ( ABC News: Graeme Powell )

Pourzand pleaded guilty to charges of attempted fraud and criminal damage by fire, with Justice Stephen Hall describing him as a "very willing, involved and interested participant in the plan to set fire to the building".

Justice Hall said, as the owner of the property, Pourzand had the most to gain from the fire, which he said would have been pointless without his involvement.

The court heard Pourzand had reimbursed the insurance company the $500,000 it spent investigating the matter, and had also given $38,000 to emergency services.

Offences shamed family

Justice Hall accepted that Pourzand had previously led "a largely law-abiding life" and his offences had caused great shame to him and his family.

But he described Pourzand's crimes as "a very serious case of their type".

He sentenced the 65-year-old to seven years and four months' jail.

Pourzand will have to serve five years and four months before he is eligible for parole, meaning with time already served he could be released at the end of 2023.