Thanks guys for your information,

I have recently found a property in Willetton WA which is just approved by council to change zoning from R17.5 to R30 which means the block (680m2) have duplex potential. However, the final approval will only take effect after minimum of 1 year and may be 2 years. During this period, I will need to rent out the house to gain some income. The asking price is around mid 600k and there is lots of vegetation (including big trees etc) and the house condition is unlivable unless I go through extensive renovation.

I base on the following calculation:

Property = 600k
Stamp duty = 25k
Renovation = 30k
Demolish, and all relevant subdivision cost = 100k (remember there are at least 10 trees with 4m and above, shrubs etc)
Interest Rate for 1 year at 4% @ 600k for 2 years= 48k
Council/water rate over 2 years = 5k

Total = Approximately 808k which is 404k for each 340m2 land. Obviously I will get some of this money back from the tax return and rental but I would like to use this money as backup for any unforseen issues with the property.

For me to be able to make money on this, I will need to sell each of this 340m2 land for 450k above at Willetton which I think is doable.
My concern are they may have some structural issues with the house, the renovating cost and time it takes and cash flow during this period.

This property is already under offer. At the time I visit the home open, I am not sure if I should just make an offer. My gut feeling it may cost more than my estimate (unless you have cash to buy) to renovate and time to rent out. I just want to hear from your opinions on the situation like this. I may find something else in the future and come to the same situation again.