Personal loan for house construction from bank .... Principle repayment eligible for 80c

You can claim deduction under section 80C in respect of principal repayment so long you are able substantiate that the borrowed funds were utilised for the purpose of acquiring / constructing the property.

Retired government teacher constructed house with his retirement funds. At the finishing of the constitution he fell short of funds so he took 9 lakhs personal loan from SBI  where he is having pension account. How can he prove that ...we won't expect a letter or something else from the Banker ... 

Assessee can consider maintaining fund flow statement showing one-to-one utilisation of funds for the purpose of construction.