"It will feel like a new home," he promised one client. "It will look a million dollars when it is finished."

But when his clients started to complain about the 53-year-old's shoddy work, Issa responded with a series of violent attacks - firebombing homes and offices and beating one client after ambushing him when he got out of a lift.

Issa was convicted last month of arson and attempting to pervert the course of justice in the Sydney Downing Centre District Court. In total, there were six alleged firebomb attacks across Sydney between March and May 2013. Issa was convicted of five.

Three of the victims were disgruntled customers of Issa's, unhappy with shopfitting and renovation work he had performed. Another was the lawyer of one of the complainants. All the targets of his bombs were connected to legal proceedings against him.

One of his victims was an inner-city restaurateur who was in dispute with the builder about whether an exhaust fan had been installed in his premises.

The dispute ended up in the Consumer, Trader and Tenancy Tribunal but five days before the June 6, 2013 hearing Issa, and two other men, attacked the man as he took rubbish to his restaurant basement.

Issa used a long metal torch to repeatedly hit the man as he collapsed inside the lift.

Another of Issa's victims told the District Court on Friday that her family had employed Issa to renovate their family home.

But when they also complained to the Consumer, Trader and Tenancy Tribunal about Issa's work, he responded late one night by throwing Molotov cocktails - made at his client's master bedroom.

The woman, who cannot be named for legal reasons, told the court that the attack had scarred her seven-year-old son who had to undergo therapy and refused to sleep alone.

"The now nine-year-old had been playing out all sorts of scenarios in his head at night - all of which ended badly," the woman told the court in a victim's impact statement.

"All because he felt Bill was going to come back and finish the job.

"When asked about why he acted the way he did when his parents went out, he simply said he thought he would die."

No one was physically injured in the bombings and there was no significant property damage but two clients withdrew their cases against Issa.

When police searched his Kemps Creek property and his business premises, they found Corona bottles with the same date and batch number as those used in the attacks.

They also found Bob the Builder bedsheets, and two victims found scraps of the same sheets had been used as wicks in the firebombs.

He was recorded expressing a preference for V energy drinks. He had pleaded guilty to assaulting the restaurateur.

Issa will be sentenced January.