According to Governments rule Builder has to sell only the carpet area. First thing you should do is check the layout or plan of the flat. In this plan all the details like-size of (in sq.ft) living room, kitchen, Bed Room, Toilets & Bathroom, the size of wall is mentioned. In this you will come to know the length and breath of the flat which is the carpet area.
The builder sells the balcony (which is actually free) to the client in full price and terrace in half the price.The balcony is approximately is 3 feet with shade over it and terrace is 7-8 ft open to sky. The builder loads over the carpet area.
Let say the flat is 500 ft,on that builder charges you 30-60% more which is called loading and gives you the rate of super built-up.(There is no standard rate for loading) Some builders charge 60%. All should know that Carpet Area is more then that of Super built-up. Many dont know that parking is free for your vehicle.
A law has been passed that the builder has to give the parking place for free, but the builder charges you anyways. It is not mentioned in Sale Deed, only the parking no. ; your flat no. ; area of the flat, rate of the flat & accordingly the stamp duty is filled.