A lot of people in India live in flats(otherwise called apartments). A lot of them do not know what would be the value of their flat if they sold it after some years( 1-20 years).
I saw an advertisement of a flat resale company which can give some clues to value your old flat. Although this is not sacrosanct, this can be used as a guideline for your research.
If you analyse the data in the advertisement you will find that:
The average cost of resale flats is as follows:
1-5 year old flat is 78% of current market price(range=75%-83%)
5-10 year old flat is 68% of current market price(range=63%-75%)
10-20 year old flat is 58% of current market price(range=50%-67%)
Some people would consider the value of undivided share of land and the value of the building and value a flat based on that. However one developer, with whom I discussed the valuation of flats said:
Once a land has been made into flats, the value of the land per se is lost. We would value the flat based on the current market price of a new flat.
This could be debated.
However, the above rules could help us make sure we are not overpaying for an old flat or selling an old flat at a reduced value.