Owning a house, for some this would be a night mare as they may not have funds to start with. So, one best thing they could do is to buy a flat with one single bedroom. But, this would not suffice and hence they would be interested in buying a second house with two bedrooms and then the next target would be for a three bed room. Instead of doing this exercise for every two years why don’t you plan perfectly and own a duplex house that would fulfill all of your dreams and would also serve the purpose of providing more space for the growing children or else for the elderly parents who would eventually migrate to the cities just because their children are working in the city and hence have to be with them either to support children in growing the grand children or else for addressing their own medical concerns.
Either way, when you plan for the custom duplex homes you do have to consult the experts so that you know the actual funds that should be raised for the construction of such a lovely house. When you start doing by self this sort of budgeting then you should and must redo this as every time you verify your calculations and numbers you would realize that you forgot to add an item that would eventually increase the overall cost of constructing the house.
Only the experts would evaluate the cost items one by one as and when you start discussing about the reasons you have for a duplex house. Once the reasons are listed out, the designs would be displayed by them which then can be customized so as to match to your tastes and preferences. When this mapping is done, the experts would then evaluate the cost of constructing the house depending on the areas you are interested in. With all the details provided to you, you could then take a final decision.