However this is however substantially different from saying lending is 80% of value (so banks only have a 20% margin before value declines start impacting the security cover of loans). The link below states Australia has 10.4m residences. The estimated value of these is A$6.87 trillion (Sept 2019). This puts the average house at A$660k. The value of residential property is therefore 4x GDP.
https://www.abs.gov.au/ausstats/abs%...D?OpenDocument
The 2018 report below puts the value of residential loans at A$1.78 trillion. About 26% of the value of residential property is represented by mortgages, the other 74% is not. This doesn't seem excessive to me, but perhaps I'm missing something. On average, there is A$171k of lending against each house.
Factoring in that 45% of properties don't have a mortgage, the average mortgage increases to A$311k but this is still slighly under 50% of the average property value - again this doesn't appear excessive.
https://www.securitisation.com.au/Li...ov-21-2018.PDF