Current PPOR is about 60 years old, mostly fibro/asbestos, not energy efficient, and to bring it nicely up to date could cost quite a lot. At the moment trying to work out the numbers on how much/feasible it will be to knockdown and rebuild in the near future. Current estimated property valuation: $520k Loan remaining: $285k Estimated equity: $235k I’m guessing the house value is low at around $50k ? Leaving land value at around $470k. For the rebuild I’m estimating presently: Knockdown + other site prep costs: $50k New 2 story/4br build: $320k Total estimated final valuation: $750-800k But this is where I am confused where the final amount owing is calculated. Some established equity must be in the land, and some in the house? Where does it go? Any idea of how I would calculate the final loan owing after the build in this scenario?