It depends on when when the house was constructed.
Between 1985-87 an allowance of 4% per year.
After 1987 2.5% . It is only based on the improvements buildings,
fences, and fixture fittings. Fixtures and fittings are at a different
eg land and house say $100k land might be $40k the balance of $60k
will be the basis of depreciation tax allowance. To get the best cost a
quantify surveyors may be the best way to go.