The housing crisis is driving a "geographic wedge" between the older and younger generations, according to a think-tank.
Those behind the report said a rise in "age segregation" amid a lack of suitable and affordable homes has been hugely damaging to society, weakening the bond between different age groups.
Across England and Wales, the number of neighbourhoods in which half the population is aged over 50 has surged since 1991, the research from the Intergenerational Foundation (IF) found.
In 1991 there were just 65 such neighbourhoods. This had increased to 485 by 2014, 60% of which were rural, the report, titled Generations Apart? The Growth of Age Segregation in England and Wales, said.
Within urban areas, older people, children and young adults are also living increasingly separately, according to the research.
"The housing crisis is driving a geographic wedge between the generations," the research said.
"It means that older and younger generations are increasingly living apart."
Since 1991, the median average age of neighbourhoods near the centre of cities has generally fallen by between five and 10 years, the report said.
The report identified Cardiff, with its large student population, as "the most age segregated city in England and Wales".
It said Cardiff city centre has become more youthful while its outer neighbourhoods have aged. The regeneration of Cardiff Bay has created homes for many young renters "attracted by a renaissance in restaurants and nightlife", it said.
Brighton, Leeds, Nottingham, Sheffield and Southampton were also identified by the report as age segregation "hotspots".
In Cardiff and Brighton, nearly a quarter of the population would need to move in order to eliminate age segregation, the report said.
Surging house prices and a lack of choice for buyers have meant many people in the younger generation have had to cast their nets wider in the search for a home they can afford. Many people are also forced to move to particular places to find suitable work.
Younger generations have become renters when they would rather be owners, while older generations face a last-time buying crisis due to a general lack of supply and a lack of affordable suitable accommodation to downsize into, the report said.
The report argued living apart makes it harder for younger and older generations to look after each other, putting a bigger strain on the NHS, as well as making it harder to share experiences.
Age segregation also reduces people's opportunities to find work and makes it harder for people to see different generations' perspectives, it said.
Angus Hanton, IF co-founder said: "Just 5% of the people living in the same neighbourhood as someone under 18 are over 65, compared to 15% in 1991. This is hugely damaging to intergenerational relations. It weakens the bonds between the generations, and leads to a lack of understanding of, and empathy for, other generations."
Nigel Wilson, chief executive officer of Legal & General, which supported the research, added: "We have created an intergenerationally unfair society. We need to take bold steps to reverse the negative trends of the last 30 years.
"This will involve not only an increase in housing supply of 100,000 a year of all tenures, but also a step up in investment in modern infrastructure and modern industries to create the jobs of the future."
To break down divides between generations, the report recommended that it should become easier for older generations to subdivide their homes where they already live, with greater intergenerational living, as well as building more homes suitable to downsize to in the right locations.
New, mixed housing developments should also be built that different generations are able to share and the building of housing developments that are only suitable for one age group should be avoided, the report said.
The report used figures from the Office for National Statistics (ONS) to make its findings.
The IF said it believes policies should be fair to all generations.
A Department for Communities and Local Government spokesman said: "Building the homes that communities need is an absolute priority for the Government and we have delivered nearly 900,000 since the end of 2009.
"We've also set out the largest housebuilding programme since the 1970s, doubling the housing budget so we can build a million extra homes."