Cook, who lives in the United States with her husband, who works as a lawyer, had flown into Sydney only a few days earlier and was shocked when they chatted about her son's stress over dinner.

"We were sitting there and he said 'I'm so stressed about money, food costs and housing costs. He was looking at another vision of renting a house," Cook said.

Later that night, she messaged her husband that they should buy an investment property to help their son.

"We could potentially spend less money because we're paying rent for him. We can take all this stress off and take advantage of the fact that the dollar is 66 [US] cents."

At noon on Friday, Cooke looked at a house in the Inner West. She was happy enough with the condition and location of the house that she went to the auction with her son the next day and walked away with the keys in what she said was a "very spontaneous" move.

"We probably would have helped them anyway, but it was something that became very stressful for the kids - the rental crisis and the cost of living."

While she acknowledges how lucky her family is to be able to help her son own a home, she is not alone.

As the bank of mum and dad shifts from smaller cash gifts to buying property for their adult children, more and more parents are taking matters into their own hands. Experts say it's the latest development in Sydney's housing crisis as parents try to help their children move out of the volatile and soaring private rental market and into home ownership. In the past year, rents for units in Sydney have soared by $120 a week.

Rhonda Yim of Bresic Whitney Inner West said it was no longer unusual for parents to buy whole houses for their children.

"It's not the first time it's happened. It's not uncommon at the moment, that's for sure," Yim said." In fact, I think I've probably seen more of this in the last 12 to 24 months."

"I've seen more cases where it's being done in the name of the parents, where the parents are actually buying an investment but it's their child's future home."

Yim says the trend of increasing help from the parents' bank will only continue as Sydney house prices start to pick up.

"The bank of mum and dad probably has deeper pockets than ever before," she says." It's something that will continue. If they want to secure housing in the current market, parents will have to continue to help their children."

Sydney's auction market is increasingly seeing similar results. A few weeks ago, a local buyer in Rodd Point bought a three-bedroom house for their son and daughter-in-law for $3.6 million.

Earlier this year, a frustrated father bought a $3.8 million Paddington row house for his 20-something children to help them avoid renting, while another father bought a $4 million house in Chiswick for his daughter.

Mario Carbone, sales agent for Ray White Drummoyne, said the Chiswick father had bought a property for each of his children.

"There's definitely more demand for buyers to come into the market from the Bank of Mum and Dad. Especially for our area, it's quite substantial to get a house here," Carbone said." It's a conversation we hear more often or frequently."

According to Ben Arrowsmith of Laing + Simmons Regents Park and Berala, a Birrong family is vying for a house at 18 Hill Road to help their young children get into the market.

Dr Lawrence Troy, Director of the AHURI Research Centre and Senior Lecturer in Urban Studies at the University of Sydney

"We've certainly seen quite a lot of that recently ...... We're seeing it more than we have in the past," Arrowsmith said." They are buying entire properties rather than giving them a deposit. This is happening earlier as well."

Even further west, some families are buying investment properties, with some using their own home equity to get their children up and running at a much younger stage of life.

Dr Lawrence Troy, Director of the AHURI Research Centre and Senior Lecturer in Urbanisation at the University of Sydney, says their recent paper concludes that young people cannot access home ownership without family support, either in kind or as a direct financial contribution.

"We now have a homeownership system based on inherited wealth," Troy said.

"If you're living independently in private rented accommodation and trying to save for a deposit, forget it. It's frustrating, but people need to wake up to that.

"There is a middle class realisation that something is seriously wrong here. We're not just talking about low-income families. It's affluent middle-class families who think they can do it on their own, but they can't.

"I want people to realise how stacked the situation is right now. Unless you have wealthy parents, your chances of getting into home ownership are diminishing."

"There is a middle class realisation that something is seriously wrong here. We're not just talking about low-income families. It's affluent middle-class families who think they can do it on their own, but they can't.

"I want people to realise how stacked the situation is right now. Unless you have wealthy parents, your chances of getting home ownership are diminishing."