Deduction u/s 80c - repayment of principal amount

No deduction will be allowed. 

The deduction is permissible, if there is income from such house taxable under the House Property Head.

The provision in this regards is as below:-

80C(2)(xviii) for the purposes of purchase or construction of a residential house property the income from which is chargeable to tax under the head “Income from house property” ........

Link to provision:-

https://law.incometaxindia.gov.in/DIT/File_opener.aspx?page=ITAC&schT=&csId=5cc58b11-ea04-4050-88b4-70686201a409&rdb=sec&yr=e5be6bdb-1fc4-42d6-ac7b-34a44fd65485&sec=80c&sch=&title=Taxmann%20-%20Direct%20Tax%20Laws