Greenfield sites and green belt land should be considered alongside brownfield plots as locations for new housing, the Royal Town Planning Institute (RTPI) has said.
The organisation has put out a new policy statement on dealing with the housing crisis, which warns the Government needs to take a "fresh approach" to where new houses should be built.
While it said previously-developed brownfield land in built-up areas must continue to play a vital role for purposes including housing, a "brownfield first" policy would not deliver its full potential if there was not enough funding to make it viable, for example for treating contaminated land.
Even with building on viable brownfield sites - some of which are seen by communities as important open spaces - as well as an increase in housing density in towns and cities, land within built-up areas will not meet all of the country's housing needs, the RTPI warned.
Some future housing needs will have to be met by building on greenfield land around towns and cities.
Planning professionals - who have for 60 years championed green belt policy which designates areas around some towns and cities as land which should not be built on to prevent urban sprawl - also said some green belt boundaries may have to change.
This should only happen through careful reviews over wider areas than single local authorities, should not affect brownfield sites being redeveloped and must ensure sure new housing areas are sustainable, affordable and delivered in a timely manner, the RTPI said.
The value of green belt is not "simply about what is ugly and what is attractive", the policy argues, saying that instead there is a need to discuss who green belts are for and their social impact as well as their role in managing urban growth.
Experts at the RTPI said housing schemes were often going ahead on greenfield land on appeal, and more strategic planning was needed to properly provide the new homes communities needed.
RTPI president Phil Williams said: "'Brownfield first' can only work with accompanying public investment.
"Without government help in de-risking and making ready brownfield sites with upfront infrastructure, many sites will never come on stream.
"This is not a crude green light that says 'build on the green belt', but we need a new approach to enable greenfield sites and green belt sites to be regarded more positively by local authorities, politicians and communities.
"As a society we need to look at the countryside and green belts beyond their recreational and aesthetic appeal, and assess how they can help to shape urban change in the most equitable way.
"The emotional debate around green belts is often about people's lack of confidence in the piecemeal decisions about housing location which have had a negative impact on local amenity.
"If the planning system and planners are allowed to work properly to ensure all developments, be they on brownfield, greenfield, green belt and intensified urban centres, are in the right place in the right scale with the right infrastructure, we stand a better chance in solving the housing crisis."
The RTPI said it had come up with its policy "housing the nation" after extensive consultations with members.
A Department for Communities and Local Government spokesman said repairing Britain's "dysfunctional housing market" was a government priority and it would soon be publishing a white paper on housing.
"We have recently announced plans to radically boost brownfield development and bring life back to abandoned sites.
"This includes £2 billion to unlock brownfield land for up to 200,000 new homes," he said.