Amid regular talk of the need for higher-density housing and less urban sprawl, there are concerns that the loss of backyards is bad for our health.

Planning expert Linley Lutton, an adjunct senior teaching fellow at the University of WA, has told ABC Radio Perth that the suburban backyard was vanishing.

"We are building the world's largest project homes; they are massive, and at the same time we are reducing the land area on which they sit," he said.

"I recently did some aerial photography looking at what is happening in Perth in the outer suburbs, and I found that houses are effectively going from boundary to boundary.

"There is no useful open space where you can plant a tree or a child can play in the garden."

As suburbs around Australia sprawl, houses are getting bigger and backyards smaller. ( AAP: Dave Hunt )

Is the loss of outdoor space cause for stress?

Dr Lutton is questioning the impact for city dwellers' health and wellbeing of not having nature available on their doorstep.

"There is a lot of research now beginning to show that urbanites are very stressed and this is having a direct impact on their mental and physical health," he said.

"Then there is another body of research which talks about biophilia, the relationship between plants and people and nature, and that's really mind-blowing.

"A number of studies confirm that people do a lot better mentally when they are able to look at trees, plants and recreate in open space."

While Dr Lutton said he was not arguing against higher-density housing developments, long advocated by the state government and local councils as the solution to Perth's expanding population, but that he questioned the preference for building surplus bedrooms over outdoor space.

"I am not arguing against higher density, but these are massive houses which are occupied by an average of 2.5 people.

"That is not increasing densities at all."

1950s planners assumed big backyards

Public parks are only part of the solution and do not give children the opportunities of unsupervised creative play, he said.

"The argument is that the kids can go to the park, which we still provide although they are very minimal.

"But that is a problem when they are very young; parents have to go with them.

"There is a really strong argument that kids develop a more agile brain if they are able to work out their own games, build cubby houses and do their own private play that they do in gardens.

"I am trying to reawaken this idea that we need to be having a debate about the healthy city, not the compact city."

Is the switch from houses to apartments right for everyone? ( ABC Radio Perth: Emma Wynne )

Developers are generally required to reserve 10 per cent of new subdivisions for public open space and recreation, a ratio that was set in the 1950s.

Gordon Stephenson, a planner from Liverpool who along with Alistair Hepburn created the master plan for Perth's suburbs in 1955, assumed that residents would continue to have large backyards when they set the 10 per cent requirement.

"What [Stephenson] argued was that we could reduce the amount of public open space, the amount of parkland, because he argued that the health benefits of public parks would be taken care of by the backyard.

"So now we still only need to provide 10 per cent but we are losing the backyards."

Julie says: "I am distressed by the loss of green space in our yards and suburbs, but I understand the need to contain urban sprawl. We are possession obsessed, and that includes the size of our homes."

'Vibrancy not for everyone'

Dr Lutton also questions the push to shift Perth residents into inner-city apartments and high-rise developments.

"They use the word 'vibrant' all the time, they talk about cafes, apartments, public transport," he said.

"That's all really good for people who want to live in apartments and are physically fit and resilient and so on, but it's really not necessarily a child-friendly approach to planning.

"When you look at the whole planning push at the moment it really treats people as if they are one homogenous type of individual."

Penny says: "So many flats in the city — how the heck was Elizabeth Quay allowed? All those trees and parkland gone. Still breaks my heart."

Ultimately, Dr Lutton said he would like to see politicians lead the way in mandating backyard space in the city.

"For a change to be brought about, the consumer is not going to push it.

"Someone needs to regulate this.