The latest annual Demographia study of 272 urban housing markets - - 23 in Australia; 28 Canada; 5 Ireland; 8 New Zealand; 33 UK and 175 in the US -- shows that while housing affordability has increased, the only affordable markets are in the United States (98) and Canada (5).

The authors, Hugh Pavletich based in New Zealand and Wendell Cox in the US, say urgent action is required to restore housing to affordable levels, so that households are not required to pay in excess of three times their annual income to purchase a house with a mortgage not exceeding approximately 2.5 times their annual household income.

According to the survey, published today, There are no affordable housing markets in Australia, Ireland, New Zealand or the UK.

The Median Multiple ratio (median house price divided by gross annual median household income) is used to rate housing affordability.

The authors says the Median Multiple has been remarkably similar among the nations surveyed, with median house prices being generally 3.0 or less times median household incomes. This affordability relationship continues in many housing markets of the US and Canada. However, the Median Multiple has escalated sharply in Australia, Ireland, New Zealand and the UK and in some markets of Canada and the United States in recent years.

There were 62 severely unaffordable markets this year, down from 64 in 2008. The least affordable markets were concentrated in Australia (22) the UK (19) and the US (11). Nine of the 11 US severely unaffordable markets were in California. There were 5 severely unaffordable markets in New Zealand and 5 in Canada

Housing in Ireland has become moderately unaffordable with a Median Multiple of 3.7, showing a trend toward historic norm of 3.0.

Irish housing had been affordable as late as the middle 1990s, with a Median Multiple below 3.0.

Dublin was the least affordable market with a Median Multiple of 4.7 and with Limerick (4.2) was seriously unaffordable. Three of Ireland's five markets were moderately unaffordable, Galway (3.2), Cork (3.6) and Waterford (3.7). Ireland had no severely unaffordable markets and had no affordable markets.

The report also highlights the impact on land restrictions on housing prices.

For example, residential land release in Sydney has been reduced from an historic average of 10,000 lots per year to less than 2,000 (in 2007). Dr Tony Recsei, who is president of the Save Our Sydney Suburbs organisation comments: "In the face of the scarcity resulting from such a miserly allotment it is unsurprising that the land component of the price of a dwelling has increased from 30% to 70%. The result has been a cost increase of some three times what it was a mere ten years ago."

The report says:“In Sydney, the monthly mortgage payment on a new median priced house would be nearly $3,000 and more than $2,500 in Melbourne. By comparison, in Dallas-Fort Worth, the monthly mortgage payment on a new median priced house would be under $800 and in Atlanta $700.”