Sarah and Richard Mattsson were both raised in the country and always wanted a big backyard, so when they were looking for a house to buy nine years ago there was no room for compromise.

Key points: South East Queensland's population is forecast to grow by 2 million over the next two decades

South East Queensland's population is forecast to grow by 2 million over the next two decades A CSIRO study found a wider mix of housing options were needed

A CSIRO study found a wider mix of housing options were needed South East Queensland's urban footprint has expanded 20,000 hectares in the last decade

"We really wanted to have the yard with some space, garden, room for a dog, just to have that typical Australian lifestyle," Mr Mattsson said.

The couple also wanted to be close to Brisbane's CBD where Mr Mattsson worked and decided on the city's inner-north.

"I didn't want to spend most of my life commuting to and from work and missing out on my children's upbringing," he said.

But the Mattsson's way of life is under pressure.

South East Queensland's population is forecast to grow by 2 million people over the next two decades with many making Brisbane their home.

Homeowners Sarah and Richard Mattsson, with their children Holly and Digby. ( ABC News: Dea Clark )

The city still has the lowest density of any Australian capital but lately it has been going up, as well as out.

A landmark report released by the CSIRO earlier this year — "Australia 2060" — signalled the country might face a "slow decline" if it failed to take action on a number of economic, social and environmental factors.

The report said an urban shift towards density, creating a wider mix of housing options and improving transport infrastructure, were among the changes needed.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 26 seconds 26 s This map shows where the region's urban sprawl started and what it's predicted to look like by 2041 ( Supplied: Queensland Government, Shaping SEQ )

One of the report's authors, Dr Tim Baynes said the challenge facing Brisbane was how to maintain the "character and liveability" of the city "while also accommodating in South East Queensland something like 30,000 new dwellings a year".

Over the past 70 years, South East Queensland's urban footprint has expanded exponentially, with 20,000 hectares being added in the last decade alone.

To curb the sprawl, the 2017 regional plan recommended that 60 per cent of all new homes be built within the existing boundaries.

Many new home buyers want to be close to Brisbane's CBD where they work. ( ABC News: Dea Clark )

Greater density is essential

Griffith University urban environment lecturer Dr Tony Matthews said greater density was not only essential, it could be desirable.

He said the transformation of former industrial suburbs, like inner-city Newstead, was an example of high density done well.

But Dr Matthews said there had been "insensitive gentrification" of other inner-city suburbs where "timber and tin architecture has been cleared away" to make way for high-rise buildings.

New townhouses for sale at Bridgeman Downs on Brisbane's northside. ( ABC News: Dea Clark )

"We don't really have a particularly sophisticated way of doing density in this country, certainly not in this city [of Brisbane]," he said.

"It's either apartment blocks, or bland townhouse developments, and nothing in between."

There has been a flurry of construction over the last decade and Dr Matthews said that had contributed to some poor outcomes.

"There's been too much demand for development approval, and there's not enough supply of planners and council oversight to properly look at these developments," he said.

Dr Tony Matthews says high demand for development approvals has contributed to some poor outcomes. ( ABC News: Dea Clark )

Woolloongabba development fuels community angst

A high-rise development at Woolloongabba in Brisbane's inner-south has been the cause of much community angst and protest.

The student accommodation building complex, Park Central, at Buranda. ( ABC News: Dea Clark )

The 1,578-room UniLodge Park Central by Singapore-listed property developer, Wee Hur, is the largest student accommodation in Australia.

"They're [students are] short-term people and they'll enjoy living there, but they're not invested in the community long-term," Dr Matthews said.

"Density and liveability can occur together but often they don't and often that's because there isn't a good vision there to begin with."

Stage three of the development has parents of the neighbouring Buranda State School up in arms, including P&C president Craig Unthank.

"This 20-storey building next to a heritage-listed school in a very quiet cul-de-sac with residents of 160 units coming in and out, I think is inappropriate," Mr Unthank said.

Craig Unthank says a 20-storey building next to the heritage-listed Buranda State School is inappropriate. ( ABC News: Dea Clark )

Traffic problems increase

In-fill developments in lower-density areas are also a sore point and have galvanised community action groups across Brisbane.

Mike Fowler has lived at McDowall on Brisbane's northside for the past 16 years, but his bushland view is about to be replaced by 44 townhouses.

"Most of the places in McDowall used to be nice suburban blocks with houses on acreage, but the land is being sold … and it really is starting to have an impact on quality of life here," Mr Fowler said

He said traffic congestion was a particular problem.

"A lot of the streets aren't very wide … and navigating your way from here out onto a main road can be problematic if there's cars parked on the side of the road," he said.

Mike Fowler's bushland view at his home is about to be replaced by 44 townhouses. ( ABC News: Dea Clark )

More parks, bikeways and transport needed

The Brisbane City Council's (BCC) response has been to come up with a plan to "protect the city's backyard" and "put a stop to cookie-cutter townhouses".

The council is seeking State Government approval to amend the Brisbane City Plan to ban medium-density development on blocks smaller than 3,000 square metres in low-density suburbs.

QUT property and planning associate lecturer Mark Limb described the move as "ham-fisted in its blanket approach" and said it "discourages a form of housing that provides low-impact density and offers good alternatives to living on the urban fringe".

He said communities could be better supported through the change with better targeted infrastructure spending on parks, community facilities, bikeways and transport.

He suggested the $130 million a year the BCC received from developers in infrastructure charges contributions needed to be "strictly apportioned" and a component spent directly on the locality concerned, rather than into a general pool.

A new townhouse development at McDowall on Brisbane's northside. ( ABC News: Dea Clark )

Fitzgibbon Chase on Brisbane's north was master-planned by the Queensland Government as an exemplar of how higher-density living could be delivered.

It offers a mix of affordable housing types, including small-lot homes, townhouses and units, plenty of green space and is close to the railway.

Katrina Gorton has lived there for three years and said she had wonderful neighbours and would be "heartbroken" to leave.

"Home ownership is high, so everyone's very respectful about living close together — we've got some elderly people living here and a lot of young families," Ms Gorton said.

Ms Gorton does not have a backyard but tends to her patch in the community garden.

Katrina Gorton does not have a backyard but tends to her patch in the community garden.

The development's community centre had also become a hub where resident Ellen Murray joined other parents at playgroup.

"The big thing for my husband and I was the affordability of being able to buy our first house … and that was something we couldn't afford to do in some of the suburbs of Brisbane," she said.

"We don't have a backyard, but we do have a park very near our house."

New mother Talitha Vuillemot lives outside the development, but visits the area regularly with son, Orson.

"The mothers who do live in the area are very welcoming … even the local coffee shop across the road is quite lovely," Ms Vuillemot said.

Talitha Vuillemot and her son Orson regularly attend playgroup at the Fitzgibbon Chase Community Centre. ( ABC News: Dea Clark )

Little change in peak-hour transportation behaviour

Higher density living is supposed to deliver sustainability benefits, like travel behaviour.

Chermside is one of Brisbane's Principal Regional Activity Centres, where high-density development is focused around the nearby shopping centre, hospital, and a major transport corridor.

New dwelling densities have increased by more than 60 per cent over the last 20 years, providing a significant boost to the local population.

But Mr Limb said there had been little change in peak-hour transportation behaviour compared to other areas in Brisbane.

"I think the idea of having the permanent job and being able to live near it for extended periods of time, doesn't align with the nature of work in modern society," Mr Limb said.

"Unless it's supported by sufficient public and active transport infrastructure investment, we'll be waiting a long time to see meaningful changes."

Mr Limb said the Australian dream of a house with a backyard was deeply ingrained and continued to drive urban spread.

"Soaring property prices in existing urban areas has put that out of reach for many, so people go where they can afford, and that's the fringe," Mr Limb said.

Apartment buildings at Fitzgibbon Chase master-planned community on Brisbane's northside.

Backyard might be out of reach

The Mattssons have acknowledged that by the time their children were buying their own homes, a backyard might be out of reach.

They have a message for Brisbane's town planners and decision-makers.

"At the very least, try and have the best public space and reserve that for people so it's within walking distance," Mr Mattsson said.

Brisbane's Lord Mayor Adrian Schrinner did not respond to the ABC's requests for comment.