The number of people who own a second home, buy-to-let or overseas property has risen by about 2 million since 2001, research claims.
A report from the Resolution Foundation shows 11.2% of adults, or 5.5m people, lived in a family with property wealth outside their main residence between 2014 and 2016.
This represented a significant increase over the last two decades, with the number of people rising from 3.6m individuals (7.9%) in 2001.
Buy-to-let made up the majority of additional properties, with 1.9m people holding this type of property wealth.
While people born in the 1950s were the most likely to have additional property wealth, increases were also seen among younger generations.
Those born in the 1970s are now around 60% more likely to hold additional property to hold additional family property wealth than other generations were at the same age.
As the increase has come at the same time as falling rates of overall home ownership, the Resolution Foundation said measures need to be taken to rebalance the housing market.
The thinktank suggested halving stamp duty on main properties, and reducing capital gains tax for owners of multiple properties when they sell to a first-time buyer.
George Bangham, policy analyst at the Resolution Foundation, said:
"Multiple property wealth has grown rapidly, with over one in ten people today owning a share of Britain's £941bn worth of second homes, buy-to-let and overseas properties.
"As the huge stock of additional properties starts to be passed on to younger generations, Britain risks becoming a country where getting ahead in life depends as much on what you inherit, as what you earn."
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