A drive to build 57,500 new homes in Birmingham by 2026 may be at risk of falling short after a ban on back-garden development.
Campaigners have welcomed a Government move to prohibit the practice of cramming new houses and flats into large private gardens.
But the change is expected to make it far more difficult for the city council to meet its house-building target by removing hundreds of potential sites for apartments schemes from suburbs such as Sutton Coldfield, Moseley and Edgbaston.
Planning Minister Greg Clark will also abolish rules stipulating that at least 30 homes need to be built on every hectare of developed land.
His decision is likely to make it easier for developers to get planning permission for more expensive bigger homes and larger gardens, again reducing the number of new properties likely to built in future years.
City council leaders enthusiastically embraced the 57,500 target, which they regard as the minimum figure if a pledge to increase the population of Birmingham by 100,000 people is to be achieved.
Although the Government has abandoned the Regional Spatial Strategy, there is no sign of the council scaling back its ambitious target.
Harborne Conservative councillor John Alden is questioning the viability of delivering such a large number of new homes in Birmingham.
Coun Alden said: “To build 57,500 houses you would require an area as large as Sutton Park. Where is such a large amount of land to come from? I have asked this a number of times, but never had a satisfactory answer.
“Now that we are to be prevented from developing back gardens, what is going to happen?”
According to the Communities and Local Government Department, the number of houses being built on gardens rose from one in ten to a quarter of new properties in England between 1997 and 2008.
Councils have struggled to stop the trend as gardens have been classified as “previously residential land”, making them brownfield sites in the same category as derelict factories and old railway sidings.
Mr Clark said: “For years the wishes of local people have been ignored as the character of neighbourhoods and gardens have been destroyed, robbing communities of vital green space.
“It is ridiculous that gardens have until now been classified in the same group as derelict factories and disused railway sidings, forcing councils and communities to sit by and watch their neighbourhoods get swallowed up in a concrete jungle.
“I am changing the classification of garden land so councils and communities no longer have their decisions constantly overruled, but have the power to work with industry to shape future development that is appropriate for their area.”
The Minister added that “wholesale reform” of the planning system would leave communities with a far greater say on development matters.
But the Campaign to Protect Rural England warned the Government ran the risk of returning to urban sprawl by ditching the density requirements and the classification of gardens as brownfield.