How do i capital gain on sale of house property?

dhruv patel (ca) (75 Points)

01 October 2013  
We have a very old property as our residence in present, and now we are going to recunstruct a new building, and we also wants to sale some of the flates. But the question is, How i calculate the capital gain, as short term by showing the new constrution or long term by showing addition in the old property??? THANK YOU....in advance