Pressure is mounting on the state government to take a city-wide approach to heritage protection, following community outrage at a string of high-profile mansion demolitions in Melbourne’s leafy eastern suburbs.

It comes three months after the Andrews government’s refreshed Plan Melbourne blueprint removed the cap on the number of homes allowed on blocks in neighbourhood residential zones – once a fortress against higher density. Planning and heritage experts say rising developer demand stemming from the changes is putting further strain on gaps in local heritage protections.

The property market is increasingly luring developer dollars to any property without heritage restrictions; agents regularly market a slew of perfectly liveable homes with “land boxes” across them. Although councils such as Boroondara are completing their own $1 million municipality-wide heritage study (the first of its kind), other councils may not have the political will or resources to undertake expensive, up-to-date heritage overlay studies.

The National Trust of Australia’s Victorian branch is calling on the state government to increase funding for councils to be able to do further strategic heritage work.

“We would like to see an increase in resourcing for heritage at a local government level across the board,” advocacy manager Felicity Watson said, adding that a holistic approach to heritage was needed. “I think there’s an urgent need do that, particularly in light of the latest iteration of Plan Melbourne.”

Ms Watson said recent examples – such as the demolition of Gough Whitlam’s Kew birth home, Ngara, and the $9.6 million Kew mansion, Forres, demolished and put back on the market as an empty block at almost double the price following the zone changes – highlighted a need for councils to review heritage policies, particularly given the concept of heritage changed.

Councils often lacked resources to do proper strategic planning work or implement regulations to get their planning schemes to a strong position, said RMIT University senior planning lecturer Joe Hurley.

“And you need both to deal with all the pressure which will come in the current climate, if you don’t have that policy in place, then it’s always a rearguard action,” Dr Hurley said. “You have these issues where [councils] say, maybe that shouldn’t have happened, but we didn’t have our house in order and it got let through.”

Dr Hurley said there was increasing tension between the protectionist local governments and the state, wanting to relax that over-protection.

“There’s two ways to go: either we say it’s open slather, open season, and wherever the market says we can make money, we should consolidate. Or we have an approach that says, ‘yes, we want this investment and consolidation, but we want a broader community engagement about where we have it and where we don’t.”

There has been an unequal application of heritage planning controls across Melbourne, according to University of Melbourne PhD Candidate James Lesh. For example, the inner city has residential protections achieved in the 1970s and 1980s as part of sustained resident advocacy.

“Why should the inner suburbs have such relatively strong residential controls, when the middle suburbs don’t? Simply because those suburbs had the right people living there at the right time, when there was the political and social will?” Mr Lesh said.

“Refreshed studies should be done for the middle suburbs, where there are numerous 19th and 20th century places that might be protected in some way.”

Boroondara mayor Phillip Healey said although the council had significant concerns about the potential for greater demolition of properties, the fact there was now no limit on the number of dwellings that could be built on one lot was its major concern.

“In the [recent Kew] example, we’ve gone from a cap of two dwellings to a result that could easily accommodate 20,” Cr Healey said. “We are very concerned by these changes and expect to see demolition of Boroondara’s wonderful period homes and neighbourhoods.”

Community concerns about heritage demolition are also predicted to increase in areas such as Yarraville, Footscray and Brunswick over coming years, with buyers spending a premium to move into neighbourhoods for their period character.

Architects who work in the area have responded to the Kew demolition by assuring local communities it would be unlikely that what was built in place would not respond to the neighbourhood’s existing character.

“The reality is no-one is doing ‘dog boxes’ in those suburbs; generally they have to cough up a bit of money for those sites, so what’s built is mostly architecturally designed and doesn’t come cheap,” Toby Ewert, director of Ewert Leaf.

He said because there was such strong competition from developers in those areas, and demand from local downsizers, there was no market for cheaply-built homes.

Nick Travers, director of Techne, said good architects would aim to work with a site’s history and, from a sustainability point of view, should incorporate objects from a house after a demolition and not just throw everything in the skip.

A spokesman for Mr Wynne said Plan Melbourne would help to protect and celebrate what made Melbourne special, such as heritage strip shopping centres. “As part of Plan Melbourne, the planning department will work with local councils to enhance and improve local heritage planning policies and assessment processes,” he said.