First, you have to sell your home, which is not always a reality. Then, a construction company has to buy your expensive house and build enough stories to make

First, you have to sell your home, which is not always a reality. Then, a construction company has to buy your expensive house and build enough stories to make up for the difference of buying, demolishing and building again. Finally, the municipality has to allow a building of that height. That's why in many areas you see townhouses that go up in price, but no developer wants to turn them into 4+ storey buildings.