Young people in Britain are spending three times more on housing than their grandparents did, according to the Resolution Foundation think tank.
They also have to cope with less space and longer commutes to get to work.
While their parents typically bought their own home in their 30s, young people will soon have to wait until their 40s.
As a result, millennials are at the sharp end of Britain's "housing catastrophe", the report claims.
Those now in their 70s and 80s spent just 7% of their annual income on housing at the age of 30, it says.
The baby-boom generation - now in its 50s and 60s - spent 17% of income at the same age.
However, millennials - those now in their 20s and 30s - spend 23% of everything they earn on housing costs.
The Resolution Foundation says youngsters are also living in smaller houses.
Since 1996, the average floor space occupied by someone under 45 has fallen by 4%. For those over that age, floor space has grown by 2%.
By the time the millennials reach the age of 40, they will each be spending an extra 64 hours a year commuting to work, compared with their parents, as they struggle to find housing they can afford.
"Britain's housing catastrophe has been 50 years in the making, but while its effects are widespread, it is millennials who are truly at the sharp end," said Lindsay Judge, one of the report's authors.
"The big danger today is that young people are having to settle for lower quality, longer commutes and less security in order to afford a place to live, despite spending a record share of their income of housing."
The Foundation - which campaigns for higher living standards - is calling on all the political parties to address the housing crisis.