- Increase housebuilding to 300,000 a year
- Set in motion at least 10 new Garden Cities
- 30,000 Rent to Own homes a year by 2020
- Ban landlords from letting out poorly insulated homes
The government would directly commission new house-building if Liberal Democrat plans for 300,000 new homes every year came to fruition.
The party said the proposal would mean fewer stalled developments and would go "much further" than the coalition government had done on house-building.
Nick Clegg also highlighted a promise of at least 10 new "garden cities" and a state-backed housing investment bank.
The announcements came ahead of Wednesday's Lib Dem manifesto launch.
Other Lib Dem proposals on housing include "rent to own", which would allow tenants to make monthly payments to acquire a stake in their home, and government loans to help working people afford a rental deposit.
"Liberal Democrats believe everyone should have the opportunity to have a decent home at a cost they can afford," said Mr Clegg.
"That's why we have increased house building in government but we want to go much further.
"And we will help young people who want a home of their own with radical plans to help them buy or rent."
The direct commissioning of homes by government agencies is being trialled at a former RAF base in Cambridgeshire.
The Lib Dems say they would roll out this policy on government or local authority-owned land. Government agencies would specify the types of homes required and arrange planning permission, without the involvement of a developer.
The party has often called for the creation of new towns, echoing the so-called garden cities built across the UK after World War Two. It said it would publish a "long-term plan" setting out in detail how its 300,000 target would be met.
Mr Clegg's housing pledge came as Prime Minister David Cameron said a Conservative government would extend the right-to-buy scheme to people living in housing association accommodation.
Mr Cameron said this meant the "dream of a property-owning democracy is alive" - but Mr Clegg criticised what he said was a "bevy of unfunded Conservative Party commitments".
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