A record plunge in first-home buyer activity has sparked calls for a national debate on housing affordability.

While the housing market has reached boom levels in a low interest-rate environment, first-home buyers are being squeezed out of the property market, making up a record low 6.8 per cent of new housing loan commitments in NSW in September, a sharp fall from the peak of 34 per cent in May 2009.

Across Australia, the proportion of first-home buyers taking out loans sank to 12.5 per cent for the month.

Property prices in Sydney have soared by 13.2 per cent over the year, according to RP Data.

Sydney and Melbourne are experiencing a run of ''super Saturday'' auction weekends. This week, 769 homes will be auctioned in Sydney and 1220 in Melbourne. It is the third week in a row that Sydney has posted more than 700 auctions on a Saturday as buyers seek to take advantage of low interest rates and improved confidence.