For the last 100 years, Australia has been building suburbia as the ideal for how one lives, and now we have the suburban sprawl, particularly in Sydney and Melbourne, says award-winning architect, author, educator and sustainable design advocate Tone Wheeler.

“But you can’t keep growing at the edges,” he says. The solution, therefore, lies in reassessing density in the suburbs, and more importantly, deciding the scale of the buildings that will replace the existing typology.

“Low and close”

The idea that a lower scale would be better when increasing density is gaining ground. By having buildings closer together but low in scale, urban density can be increased without overwhelming neighbourhoods with multi-storeyed or high-rise structures. So, what type of building can substitute for suburbia while maintaining comfort, liveability, and affordability?

The answer, says Wheeler, lies in the return of a forgotten model – the humble three-storey brick walk-up apartments that once quietly defined our suburbs before being effectively regulated out of existence in the 1980s by most councils for being “ordinary looking” and “too big to go in a single- or double-storey place”.

The three-and-four-storey walk-up flats were commonplace in all the original suburbs, built within walking distance to shopping centres, adds Think Brick Group CEO Cathy Inglis. “A traditional build that just stopped.”

“It's actually a fantastic form of building,” notes Wheeler. The apartments have cross-ventilation and natural light, they are easy to access because they are either on the ground floor or up a couple of levels, and they are really durable. “They've lasted.”

Many of these apartments are being renovated now, adds Inglis, and all they need is a coat of paint or a new kitchen or bathroom, because the building is solid and will last for a very long time. “One of the most sustainable things to do is to use what's there.”

The three-storey walk-up was also efficient to build with just four apartments per floor, a centre stairwell and a unit in each corner, which ensured privacy for all. And contrary to what the councils thought, these buildings weren’t that much bigger than the surrounding houses.

There are also social benefits in living in these buildings, being a small-sized strata, where everybody knows everybody, observes Wheeler, unlike modern apartment towers where strata bodies are a big issue with the huge number people who are strangers to each other.

Walk-ups are simpler and cheaper to build

Besides, the walk-up model is really a good solution for builders at the moment. According to Inglis, it involves a simple structure featuring loadbearing masonry and concrete slabs without any complicated waterproofing details, basements, elevator or things that add complexity, and importantly, the cost factor – not just in the build but over the life of the building for the owners in strata fees.

“Simplifying the building structure and construction is going to make it cheaper not only to build but also to maintain over the life of the building,” she notes. This approach could dramatically broaden the base of builders capable of delivering medium-density housing.

A number of builders are reluctant to move from Class 1 (houses and duplexes) to Class 2 (apartments) buildings because of the complex details involved in terms of mechanical, electrical, and plumbing (MEP) issues or the additional features required by regulation in multi-storeyed structures. However, a three-storey walk-up, which is also categorised as Class 2, is under four storeys, and has very simple MEP, which can be handled easily. “It's not that big a step up for bungalow builders,” says Wheeler. “A duplex is already two storeys and is a concrete build with a firewall. Going from a two-storey duplex to three-storey walk-ups – it's not that hard.”

Wheeler worked with Think Brick to develop designs for a three-storey walk-up based on loadbearing brickwork and standard detailing and construction, and got it costed. They, then put the same apartment design in a six-storey building – an elevator apartment with a basement for carparking, hydrants, pump rooms, electrical rooms and communication rooms – and compared the costs. The walk-up cost about $429,000 to build while the same apartment with the same size and design in a six-storey building, amounted to $540,000.

It’s a significant difference, says Inglis, thanks to all the extra details that need to be added to go from three storeys to six storeys. “This is a more affordable way to build,” she explains, given the current affordability problem. “To have more affordable living at this smaller scale in our existing cities is a great way to do it.”

Planning rules now allow three-storey Class 2 buildings in the R2 Low and Mid-Rise (LMR) zones, where previously only two storeys were permitted.

“Is it a bad thing if a three-storey building is next door to a two-storey duplex or single-storey home?” asks Wheeler. “No. It fits in that context. That's the low-rise, medium-density solution.”

Besides, a good tree can visually soften the height of these three-storey walk-ups from the street – something much harder to achieve with four- or six-storey residential structures.

He points to places like Rose Bay and Bondi where entire neighbourhoods of three-storey walk-ups remain some of Australia’s most sought-after addresses. Walk-ups, he reiterates, are cheaper to build, making financial sense, and they also make social sense because there's more of a sense of community and connection in a small block of flats. “And environmentally, it's much more sustainable.”

Low carbon construction materials: Ready and getting better

According to Inglis, an experienced materials engineer herself, there are several options for low carbon materials now with more coming on the market all the time. The traditional brick and masonry have undergone significant carbon reduction over the past two decades. For instance, the brick industry has cut emissions by half through more efficient kilns, and innovations such as higher brick coring that reduces fuel use during firing, waste-derived additives, and the use of biofuels with natural gas.

On the concrete masonry side, supplementary cementitious materials such as fly ash, slag, and limestone significantly reduce cement content – the primary source of concrete’s carbon footprint – helping produce lower carbon cement blocks, for instance. Low carbon cements are also being integrated into standards and specifications for cement mortar. Additionally, technological advancements are helping companies explore alternate fuels and manufacturing improvements to lower the carbon footprint of individual products even more.

As for the perception that sustainable materials are more expensive, Inglis responds: “Building a sustainable home with low carbon materials, good design and good thermal performance, doesn't necessarily have to cost you more money.”

Sustainability used to be about energy and water, notes Wheeler, but now it’s also about wellness and maintenance. The wellness aspect is mostly about thermal comfort, especially for the elderly and children, and being able to survive in a climate that's getting more and more extreme. Designing homes with double glazing and better insulation, building smaller houses to economise cooling and heating, and using low VOC materials with better finishes will all contribute to wellness.

Maintenance is also an important element of sustainability, but often gets overlooked, says Wheeler. The 100-year-old three-storey walk-up flats with their terrazzo floors, solid doors and brick facades don’t need a lot of maintenance and continue to look good.

Going local with the supply chain

According to Inglis, Australia has the capacity to build all the homes needed to achieve the housing targets using locally sourced materials such as bricks and concrete masonry without relying on imports.

Structurally, bricks are really powerful, says Wheeler. “You can support a three-storey building just on the bricks alone and they've got huge thermal mass.” Though bricks are heavy to move around, automation has made it much safer in factories, during deliveries and onsite. Besides, brick and concrete buildings are resilient and can survive extreme weather events.

The role of planning in boosting density

While suburbs have substantial infrastructure, services, shops and schools, underutilisation is a major problem with not enough people living there to support the local facilities.

So, how do you increase density in the missing middle? Definitely not by giving it a wholesale boost with a 20-storey tower, says Wheeler. It has to be done incrementally through a huge number of very small changes because the intent is not to rebuild the whole suburb as a complete urban renewal.

Next, how do you insert small, modest buildings such as the three-storey walk-up in the right areas? Both Sydney and Melbourne have identified areas where this is possible, informs Wheeler. In Sydney, this is being achieved through low and medium rise mapping that identifies places close to shopping centres, service centres, and railway stations, for instance.

A study conducted by Australian architect Rob Adams as planner for the City of Melbourne, looked at how much of Melbourne would have to be changed to double its population within the same outline. Using shop top housing – a form of three-storey walk-ups with retail at the ground level – as the template, the study revealed that “it would only take about 6% of the urban area to increase its density to somewhere between three and four storeys and you could double the population inside the same area”.

Sydney, on the other hand, is a whole series of subcentres such as North Sydney, Parramatta, Chatswood, Hurstville, Penrith and Liverpool. It's around these subcentres that housing should be increased, says Wheeler, but not necessarily in towers – the idea being to rework suburbia into three, four or five times the density, not 20 times.

It's that kind of understanding of the urban geography that is now going into planning, he adds. “Planning used to be about zoning and keeping things apart and separating. Now planning is about trying to bring things together, trying to stitch a city back together.”

Listen to the podcast version of this article here.

Image: Cathy Inglis (left) & Tone Wheeler (right).

Architecture & Design Team

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