Two roof repairers have been caught red-handed trying to jack up prices for property owners whose homes were ravaged by last year's hailstorms in Sydney.

Key points: Two Sydney roof repairmen tried to lift prices for home owners and insurers affected by the 2018 Sydney hailstorms

Two Sydney roof repairmen tried to lift prices for home owners and insurers affected by the 2018 Sydney hailstorms They discussed their plan on a Facebook group, leaving evidence for the ACCC

They discussed their plan on a Facebook group, leaving evidence for the ACCC It is a breach of competition law when rival businesses discuss how much to charge customers

It was the most expensive catastrophe for Australian insurance companies in 2018, as tennis ball-sized hailstones caused more than $125 million worth of damage to thousands of homes and motor vehicles.

But one repairer, Mark Lee Burtenshaw thought it would be the "perfect opportunity" to lift prices for victims of the hailstorm.

Mr Burtenshaw, the director of ANZ Roofing, even posted his idea on two roofing industry Facebook groups last December, which left a trail of evidence for the Australian Competition and Consumer Commission (ACCC) to investigate him.

"I think this latest storm is the perfect opportunity for the roofers of Sydney to increase pricing across the board as a standard that doesn't decrease!" he wrote, while posting a photo of a large hailstone in his hand.

Brent Callan-Kerkenezov, another roof repairer, was on board with the plan.

"Let's all agree that we start from $65 [per square metre] and go up!" he replied.

He also said any "roofers" who perform this work for less than $55 per square metre "need an uppercut".

The ACCC also investigated Mr Callan-Kerkenezov, the director of Ivy Contractors, about that comment he posted on Facebook.

'Outrageous' and 'anti-competitive'

The competition regulator eventually decided not to fine the two men due to the small size of their businesses, and because they cooperated with its investigation.

However, they had to sign enforceable undertakings acknowledging that their social media discussions — about setting minimum rates to repair damaged homes — were "likely to constitute an attempt to fix prices".

It was essentially an agreement not to breach competition laws in the future, otherwise they will be taken to court by the regulator.

"Any attempts to take advantage of people whose homes were damaged in natural disasters like hailstorms is something the ACCC takes extremely seriously," said ACCC chairman Rod Sims.

"The community will not just find this outrageous, it is also anti-competitive, and illegal under Australian competition laws.

"Businesses must remember that attempts by competitors to set prices or share pricing information, whether on social media or in any other forum, are likely to breach Australian cartel and concerted practices laws."

Both roof installers also promised not to repeat their behaviour and will receive compliance training in competition and consumer law.

Mr Burtenshaw has since removed the questionable posts from Facebook.