How do you work out the value of a house that has no permits or council approval? Do you first work out value if it was legit, then take a certain percentage off?
NO! More info required. Is the house capable of being retrospectively approved? On rural land? or residential? Is it 100 yrs old and OK because they did not issue council permits then? or if they did they are lost or archived?
Ask a valuer. I value them at the cost of the land minus the cost to demolish. Looked at one recently and gave it a miss. Unless the location is amazing, the price is low, and there is no other land around, where's the benefit for the buyer? The seller would do well to look at council approval in my opinion.