An international survey of 325 global housing markets shows that housing in Dublin and Cork -- the two biggest urban areas in the Republic of Ireland - -  is seriously unaffordable.

The 2011 Annual Demographia International Housing Affordability Survey (data 3rd Qtr 2010), published Monday, has been expanded to 325 urban markets of Australia (32 urban markets); Canada (35); Hong Kong, China (1); Ireland (5); New Zealand (8) United Kingdom (33) and the United States (211).

The report says for housing markets to rate as "affordable", housing should not exceed three times gross annual household income (the Median Multiple). If this "affordability threshold" is breached, it indicates local political impediments to the provision of affordable housing that need to be dealt with.

The authors say that historically, the Median Multiple has been remarkably similar in Australia, Canada, Ireland, New Zealand, the United Kingdom and the United States, with median house prices having generally been 3.0 or less times median household incomes in the principal affordability indexes (historical data has not been identified for Hong Kong). This affordability relationship continues in many housing markets of the United States and Canada. However, the Median Multiple has escalated sharply in the past decade in Australia, Ireland, New Zealand, and the United Kingdom and in some markets of Canada and the United States.

In 2010, housing in Ireland overall was moderately unaffordable with a Median Multiple of 4.0. Housing was generally affordable in Ireland as late as the middle 1990s. In today's report, Dublin was the least affordable market with a Median Multiple of 4.8 and along with Cork (4.1) was seriously unaffordable. Three of Ireland’s five markets were moderately unaffordable, Waterford (3.2), Galway (3.6) and Limerick (4.0). Ireland had no severely unaffordable markets and had no affordable markets.

The 325 markets are ranked by housing affordability in Schedule 1. All of the 115 affordable markets (having a Median Multiple of 3.0 or below) were in Canada and the United States (Table 5). There were 106 affordable markets in the United States and 9 affordable markets in Canada. There were no affordable markets in Australia, Ireland, New Zealand or the United Kingdom.

The median home price is the level at which half of all homes are sold for more and half are sold for less.

The most affordable major market (over 1,000,000 population) was Atlanta, with a median house price of $129,400, and a Median Multiple of 2.3. Indianapolis ($120,200) and Rochester ($121,500) tied for 2nd most affordable major market, at a Median Multiple of 2.4. Cincinnati, Cleveland and Detroit tied for 4th most affordable, with a Median Multiple of 2.5, followed by Buffalo, Las Vegas and St. Louis at 2.6. Eleven other US major markets were rated affordable, including fast growing Dallas-Fort Worth (2.7), Houston (2.9), Jacksonville (2.9) and Nashville (2.9).

All major markets in Australia and New Zealand, as well as Hong Kong were severely unaffordable.

Hong Kong ranked as the least affordable major market (82nd), with a median multiple of 11.4.

Sydney ranked second least affordable (81st), with a Median Multiple of 9.6, having slipped behind last year’s most unaffordable market, Vancouver at 9.5, which ranked 80th. Melbourne ranked 79th, with a Median Multiple of 9.0. Plymouth & Devon, San Francisco, London and Adelaide all had Median Multiples of more than 7.0 (Table 4).

Hugh Pavletich of New Zealand's Performance Urban Planning, the initiator and co-author of the Annual Demographia International Housing Affordability Survey says: "For metropolitan areas to rate as 'affordable' and ensure that housing bubbles are not triggered, housing prices should not exceed 3.0 times gross annual household earnings. To allow this to occur, new starter housing of an acceptable quality to the purchasers, with associated commercial and industrial development, must be allowed to be provided on the urban fringes at 2.5 times the gross annual median household income of that urban market (refer Demographia Survey Schedules for guidance)."

"The critically important Development Ratios for this new fringe starter housing should be 17 – 23% serviced lot - -  the balance the actual housing construction."

The fringe is the only supply / inflation vent of an urban market."