These 2 key charts worry Fidelity about house prices.

" Fidelity International says the Australian housing market appears overvalued on three key measures and is a risk for investors, with unemployment and rising interest rates the potential triggers for a correction. Paul Taylor, the highly rated manager of Fidelity's Australian Equities Fund, said there were two questions investors needed to ask about the housing market – is it fundamentally overvalued and what catalyst would shine a spotlight on that overvaluation and create a market reaction? " 

http://www.afr.com/markets/equity-markets/fidelitys-paul-taylor-is-watching-for-two-triggers-to-spark-house-price-falls-20180507-h0zrbb

"It should be noted that on a nominal aggregate incomes to dwelling prices measure, the Sydney market is approximately 45 per cent overvalued. SQM Research expects this over valuation to wind down somewhat over an extended period of time."

http://www.afr.com/real-estate/sydney-and-melbourne-house-prices-could-fall-as-much-as-4-per-cent-says-sqm-20180506-h0zpq5