Young first-time buyers will get a 20% discount on their new homes, under plans announced by the Conservatives.
David Cameron has set out plans to build tens of thousands of new homes on commercial "brownfield" land, reserved for first-time buyers, under 40.
As Tories begin gathering in Birmingham for their annual conference, the PM said a Conservative government would implement the plan if they were re-elected in 2015.
Homes built under the proposed Help to Buy: Starter Homes scheme would be exempt from a range of taxes, lowering their price by 20%, say Tories.
First-time buyers have been priced out of many areas, especially in LondonIn an interview with The Sun, Mr Cameron said the programme would deliver 100,000 starter homes over the lifetime of the next parliament.
"We want to help more young people achieve the dream of home ownership so today as part of our long-term economic plan I can pledge we will build 100,000 homes for young, first-time buyers," he said.
"We will make these starter homes 20% cheaper by exempting them from a raft of taxes and by using brownfield land.
"I don't want to see young people locked out of home ownership.
David Cameron says the new homes would be exempt from some taxes"We've already started to tackle the problem with Help to Buy mortgages - and these new plans will help tens of thousands more people to buy their first home."
The Conservatives said the homes would be built on brownfield land already zoned for development but no longer needed for industrial or commercial use.
Such land is not normally made available for housebuilding and can be bought more cheaply than other land, and the savings will be passed on to the buyer.
Public sector land which is surplus to requirements will also be brought into the scheme.
At the same time, the Conservatives said that the properties would be exempt from most of the taxes imposed on new homes.
These taxes include the social housing requirement and the community infrastructure levy.
Some future regulations such as the zero carbon homes standard will also not apply to properties built under the scheme.
The announcement is intended to set the tone for the party's final annual conference before the country goes to the polls next May.