Housing loan examption

Dear Experts.,

We have purchase a new house (Tenement) in the year 2009, and we have borrow / Loan taken 1st time from the HDFC Bank Ltd. Now we planned to build / Fresh construction on Tenement i.e. 2nd Floor. We have already completed First loan. Now want to know If, I have taken a 2nd Loan for construction of 2nd Floor only for Own purpose then how much exemption got in the Income Tax Act under the head " Interest on hosing  loan " as well as Under section 80C.