Young Australians have fewer opportunities for full-time work and affordable housing, creating a new "precariat" social class lacking security and predictability, according to a new book.

Jennifer Rayner, author of Generation Less: How Australia is Cheating the Young, said policies skewed towards the older generation dramatically increased disparities between the young and the old.

Sam Johnston, 26, has struggled to find a full-time job as a music teacher. He shares a three-bedroom house with his girlfriend and another couple. Credit:Paul Jeffers

This, she said, had placed an "enduring handicap" on those born from the 1980s onwards.

"There have always been gaps between younger people and older people in Australia, and that's true everywhere because young people are starting out in life, because they haven't had as much time in the workforce," Ms Rayner said.