David Cameron, the party leader, told an Age Concern conference that houses should be designed to be suitable for every stage of life. “We must think in a new way about housing design and urban planning. Housing in Britain never seems to be built with a whole lifetime in mind,” he said.

New homes tend to be either small flats, which are not suitable when people have children, or tall houses, which aren’t suitable when people become old and less mobile. Although only a quarter of people say they want to live in flats, more than half of all new properties are flats.

“We’re sqeezing more and more housing into smaller and smaller spaces. This means less room for elderly parents. We’re disrupting the generational relationship.

“We need to change the planning rules so that we get fewer small flats and more homes with gardens. Fewer homes designed for young single people, and more designed for life — universal design,” Mr Cameron said.

The new homes, also called lifetime homes, would be designed to ensure that people never had the need to move. Rather than being tall and thin with winding staircases, which are bad for elderly people, they would be flatter and wider, and even bungalows. They would tend to be more spacious to cope with wheelchairs, with gardens for the family stage of life.

The Joseph Rowntree Foundationhas proposed 16 detailed requirements, many of which are already legal stipulations for public buildings, which must be fulfilled before a house can be categorised as a “lifetime home”. These adaptations would ensure that old people could carry on living in the house.

Michael Gove, the Tories’ housing spokesman, said: “Thought has to be given so that people aren’t trapped in one or two rooms in multi-storey houses. It means more bungalow living, as opposed to less flexible vertical houses.”

A spokeswoman for Age Concern said that as the number of elderly people grew, it would be increasingly important that their needs were incorporated into the designs. “The problem is that not enough homes are built to last a lifetime. Many people find living in their home more difficult as they grow older and often have to make the difficult decision to move on, for example to a retirement flat. The concept of a lifetime home addresses the changing needs of people as they age and is a very welcome one.”

Far from costing money, the foundation suggests that it would save taxpayers £5.5 billion over 60 years in reducing the need for adaptations to existing houses and moving people to care homes. However, it would mean houses occupying larger plots of land, compared with thinking that encourages high-density housing. Mr Gove insisted that the Conservatives would protect the green belt around cities, but that more greenfield land would be used.

“The future lies in allowing communities to expand outwards not just upwards. We recognise that if we are to meet future housing need, you will have some currently undeveloped land which will have to be developed,” he said.

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