Politicians and the powerful property lobby continue to argue that building more houses is the solution to Australia's chronic affordability problems.

But a "supply-side solution" — as propounded by NSW Premier Gladys Berejiklian as well as Prime Minister Malcolm Turnbull and Treasurer Scott Morrison — will only work if affordability is just a supply-side problem.

Evidence suggests this is not the case.

In fact, our analysis shows that Australia is almost a world leader in rates of new housing production.

How Australia compares

One way to assess Australia's supply performance is to compare it with other developed countries.

The graph below compares the number of dwelling completions per 1,000 persons across 13 countries, for the years 2010 and 2015.

On this measure, Australia's new housing production is second only to South Korea's.

Australia delivers two-thirds more homes per 1,000 persons than the US and four times more than the UK.

When we measure supply as a proportion of existing stock, Australia again ranks second with a rate double that of the US.

Dwelling completions per 1,000 persons. ( OECD/World Bank )

A slightly different approach takes into account population growth.

This involves measuring dwelling completions per head of new population. Here Australia's performance sits in the middle of the pack.

We are delivering just over 0.5 dwellings per head of new population compared to more than 2 in South Korea.

This rate is, however, still ahead of the UK and comparable to the US. Again, that suggests inadequate supply is not the major cause of the affordability crisis.

Dwelling completions per capita: new population. ( OECD/World Bank )

State comparisons of supply

At a national level, supply seems pretty healthy. But there are significant state variations. This might, on the surface, be used to explain different patterns of price growth.

The table below shows that New South Wales has produced fewer new homes per 1,000 people than Australia overall over a 30-year period. The difference was particularly marked between 2005 and 2015.

However, higher supply output in the other states has certainly not created affordable markets.

In NSW, the last two years have delivered significant supply growth yet prices have continued to rise just as fast.

So why do prices rise with supply growth?

Demand drives supply

In a market-driven housing system, price stimulates new housing supply.

In Australia new supply has responded relatively quickly to price rises (despite the continuous rhetoric from the property lobby about planning).

But there is always some lag due to the time it takes to secure necessary approvals and physically construct property.

There is no such lag with demand meaning there is often a sustained mismatch between the two — positive or negative.

In a rising market, development becomes more profitable and land values rise, meaning greater returns for all concerned.

Potential future capital gains stimulate investment activity. Price rises also allow owner-occupiers to trade up as the equity in their own dwelling increases.

In such circumstances, increased levels of housing supply do little to satiate demand created by population growth and the appetite of investors.

Western Australia has had an incredible level of housing completions over the last 30 years, as shown in the table, with 2014 and 2015 particularly strong.

In the last 12 months, dwelling commencements have collapsed by more than 25 per cent.

Prices have been falling slowly for almost three years driven by the contraction in the resources sector and strong levels of new supply.

However, even under these conditions, WA housing affordability shows little sign of improving for those on low incomes.

The market still cannot deliver housing for those at the bottom end of the market.

The housing market is simply unable to deliver housing that is affordable to those on lower (and, increasingly, moderate) incomes because there is a minimum cost of delivering housing that meets minimum community standards.

This is made up of the land price, the physical construction costs of the dwelling, and the profit required for taking on the development risk.

This is why market intervention and subsidy are essential to deliver options for those on low incomes.

Targeted interventions are needed

Two strategies are needed to deliver affordable housing to the lower end of the market.

First, demand-side measures need to be better targeted to stimulate investment in new supply, particularly affordable rental housing, rather than simply fuelling demand.

Second, any government serious about improving affordability needs to put more resources into the community housing sector.

This could be funded in two ways: partly by taxing the windfall gains from development and partly by reallocating existing demand-side subsidies.

The community housing sector can operate counter-cyclically. This means it can maintain housing supply even when house prices stagnate or fall — which is good for the economy.

A bigger community housing sector is the supply solution Australia really needs.

The bond aggregator model currently working its way through consultation offers some hope of delivering this expansion.

Targeting supply to deliver housing for those on low incomes and reining in demand-side incentives that fuel prices will make some difference to affordability for those most affected.

There was some encouragement over the weekend. Scott Morrison discussed the rental market and social housing as part of the affordability solution.

This was a welcome change from trotting out the tired old supply arguments and threatening to fuel demand through more home ownership incentives.

Let's hope the treasurer follows through and delivers some much-needed "whole of housing market" thinking in the May budget.

Steven Rowley is director of the Australian Urban and Research Institute's Curtin research centre and associate professor in Curtin University's school of economics and finance.

Nicole Gurran is a professor in the Urban and Regional Planning Program at the University of Sydney.

Peter Phibbs is chair of Urban and Regional Planning and Policy at the University of Sydney.

Originally published in The Conversation