Young people trapped by high property prices face having to save for up to 30 years before they can afford a deposit on their first home, a charity has said.
Independent research commissioned by housing charity Shelter shows that people in their 20s have become locked out of home ownership, meaning a generation will be stuck renting for longer.
The study looked at earnings, house prices, rents and spending on essentials in local authorities across the country to show the extent of the challenge faced by households wanting to save up for a deposit to buy a home in their area.
Nationally, it found that couples who start a family in their 20s could be saving for a deposit for 12 years - nearly double the time faced by childless couples.
In some cases this could mean their children would be in secondary school before they own a home.
Couples without a child face an average of six and a half years of saving, and almost double that time in London (11 years).
Single people face the greatest barriers to home ownership.
A single person could need more than 14 years to save enough for a deposit unless they can find a partner, trapping many in uncertain private renting or forcing them to live with their parents well into adulthood.
The report also reveals dramatic regional variations in the time it takes first-time buyers to save in different parts of the country.
In nearly two thirds of areas in England (60%), couples with a child could face over a decade of saving for a deposit for a home of their own.
London is badly affected - with single people facing an average of 30 years of saving, while couples with children face 21 years.
The problem is not confined to the capital - high outgoings and house prices combined with lower incomes mean couples with a child in Devon, Cornwall and Leicester would need longer to save for a deposit than the same couple living in some areas of London.
Shelter has created an online calculator for people to find out how long it would take them or their children to save for a home of their own in their area, based on their individual circumstances.
Lauren Pinney, 28, from Brighton, said: "My husband Ivan and I have tried everything to save for a deposit. We moved out of our one-bedroom flat and tried living with my parents for a while.
"Now we live in a flatshare with friends to keep costs as low as possible, but with bills, rent and the cost of living going up, it's just impossible.
"We both earn decent salaries, but it's just not the same as it was in my parents' generation.
"We want to start a family but we've had to resign ourselves to the fact that saving for both a child and deposit is not going to happen and we may never own a home of our own."
Shelter chief executive Campbell Robb said: "This is the first time research like this has been conducted at a local level to reveal the harsh realities that 'generation rent' is having to confront because of our shortage of affordable homes.
"Despite working hard and saving what they can each month, today's young people face life-changing choices between starting a family or buying a home of their own. Imagine a 28-year-old couple weighing up their options: they can save for a home now and put off starting a family until they're 35, or they can start a family now but accept they'll be renting until their child is a teenager.
"Meanwhile, single people face an added pressure to either find a partner or to live with their parents well into their 30s if they're ever to have a hope of saving enough for a deposit.
"It seems the only ones with any hope left are the few who can resort to the bank of mum and dad. But with so many parents already feeling the squeeze, this is not a sustainable option.
"When we have young people working hard to save up for a home of their own to no avail, it is obvious that the government has to start meeting people halfway. Unless we see radical action to tackle our chronic shortage of affordable homes, the next generation of young people will find it even harder to find a place to call their own."
Figures released earlier this month show that the number of affordable homes completed in 2012/13 was down by 29% from the previous year, contributing to a chronic undersupply of homes which forces up rents and pushes house prices and deposits further out of reach.
Shadow housing minister Jack Dromey said: "This research shows the scale of the housing crisis and the impact it is having on young people and families, who are locked out from home ownership.
"David Cameron simply has no answer to Britain's housing crisis. Despite re-launching his 'Get Britain Building' programme four times and making hundreds of announcements, the number of affordable homes being built actually went down by a third in the last year.
"Labour has been calling for urgent action to tackle the biggest housing crisis in a generation. We need to bring forward investment in house building to tackle the chronic shortage of affordable homes, help the next generation find a home of their own, create thousands of jobs and apprenticeships and rebuild Britain for the future."
Housing minister Mark Prisk said: "In fact, the evidence shows that affordability has improved under this government, with housing at its most affordable since 2003 and the higher number of first time buyers since 2007.
"We are building 170,000 new affordable homes across England, and have introduced a package of measures to help people move onto and up the housing ladder."