Treasury Secretary John Fraser says Sydney's housing market is showing "unequivocal" signs of a housing bubble, as are up-market areas of Melbourne.

He has pointed to the proliferation of television home renovation shows, saying they are a sign of the way in which low interest rates are affecting Australia's culture.

Treasury secretary John Fraser says low interest rates are creating risks in housing. Credit:Sean Davey

"When you look at the housing price bubble evidence, it's unequivocally the case in Sydney, unequivocal," Mr Fraser told senators on Monday, at an estimates hearing.