David Cameron has pledged to get the planning system "off people's backs" and revive the economy by easing restrictions for homes and businesses.
Tens of thousands of families will be allowed to extend their properties by up to eight metres without gaining full permission, and rules on shops and offices expanding will be loosened. Obligations for including affordable housing in new developments could also be waived where they are holding projects back.
But Labour insisted the Government was "kidding itself" that the package would shake the country out of its malaise.
Under the changes, full planning permission - required for extensions of more than a few metres from the rear wall of any home - will only now be needed for those beyond six or eight metres, depending on whether it is terraced or detached.
Businesses will be able to expand shops by 100 square metres and industrial units by 200 square metres. Shops and offices will be allowed to develop up to the boundary of the premises.
Another 16,500 first-time buyers are also to receive help getting on the housing ladder under an extension of the FirstBuy scheme to be announced by the Prime Minister and Deputy Prime Minister. Would-be homeowners without a deposit are given an equity loan of up to 20% of the purchase price under the scheme.
Ministers have also decided that developers will no longer have to wait five years to apply to change affordable housing requirements if they are making sites "commercially unviable".
However, Deputy Prime Minister Nick Clegg insisted the change would be more than compensated for by extra Government investment to support the building of more affordable homes.
Treasury funding of £300 million has been found to help provide up to 15,000 such properties and bring 5,000 empty homes back into use, Downing Street said. And new legislation will provide Government guarantees of up to £40 billion of major infrastructure projects and up to £10 billion of new homes, including a move to guarantee the debt of housing associations and private sector developers.
The Prime Minister's official spokesman said Whitehall would intervene if town halls did not consider developers' requests to drop affordable home restrictions quickly enough. "We want to see it happen quickly, and where councils aren't dealing with things quick enough we will be applying some pressure," he told reporters. Downing Street said a month-long consultation on allowing larger extensions without planning permission will start next week with an aim of the measures being in effect by the end of the year.