Construction work not upto the mark

Without having agreement, I have given first floor construction work to the neighbor resident cum civil contractor on trust basis , but he constructed the building which is leaking within 3 months time before handing over the building to me in the last mild rain itself in Sivakasi. I stopped the work and asked him to vacate him from the work. I have given other party to finish balance work. Now claim Rs.4 lakhs for the non quality work. But I need spend Rs. 6 lakhs to rectify the fault made by him. Advise me further.