Former shops could be turned into homes as online shopping reshapes high streets, Theresa May has said, as she called for a “great national effort” by the government, developers and councils to tackle the housing crisis.

Answering questions after a speech in London on Monday, the prime minister said fresh approaches were needed, including using disused buildings of various types to create new homes.

Asked whether this should include retail spaces, May said it was important to prevent high streets from being hollowed out.

“Retailing is changing, with buying more goods online, and one of the elements of the new planning rules we’re setting out is to make it easier for shops to be turned into housing if that’s appropriate, but also for development above retail units to take place,” she said.

“Often there’s a very good argument for having homes being built in the centre of town, accessible to shops, accessible to transport infrastructure as well. And greater extension upwards can be, I think, one of the solutions for ensuring we’re building enough homes.”

In a 25-minute speech to the Royal Town Planning Institute conference, May described what she called a broken housing market and a resultant loss of social mobility and community, with younger people justifiably angry at being excluded, increased exploitation of renters and a problem of rough sleeping.

Overcoming this required a united effort, she continued. “It’s so important, not just for individuals, and for that British dream, but for communities, and people’s stake in the communities, that they’re able to feel that they do have a home of their own.

“What I’m encouraging people to do is to see this as a great national effort – all of us coming together, playing our role to ensure that we do deliver those homes.”

The speech contained only limited solutions, mainly based on streamlined planning process and efforts to press housebuilders to construct homes rather than sitting on land as an investment.

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May dismissed calls to let councils borrow more easily to construct further social housing, and she faced criticism from the Local Government Association, which rejected her argument that councils were a significant part of the problem.

Gary Porter, who chairs the LGA and is the Conservative leader of South Holland council in Lincolnshire, said that in the past 12 months councils had granted nearly twice as many planning permissions as the number of new homes that had been completed.

“The truth is that councils are currently approving nine in 10 planning applications, which shows that the planning system is working well and is not a barrier to building,” he said.

Porter said the government proposal to put independent inspectors in place where councils were seen to be blocking housing development was “unhelpful and misguided”.

The primary way to increase the number of homes being built was to allow councils to borrow money to construct their own, he said. This was suggested last year by the housing and communities secretary, Sajid Javid, but blocked by the Treasury.

In a section of the speech targeting developers, May criticised the “perverse incentive” of bonuses to bosses of such companies being based on profits rather than the number of homes they build.

Asked after the speech how she would hold developers to such “Stalinist tractor production” targets, May said the Conservative MP Oliver Letwin had been tasked with examining the matter and would come forward with proposals.

May said that talking to young voters during last year’s general election campaign made clear that many were justifiably angry at the unaffordability of homes and the consequent rises in wealth inequality.