80k for waterproofing is a fine rate?

Hai.. we have a 1bhk individual rental home in kundrathur. Due to some leakage issues. We enquired regarding waterproofing. They gave an estimate around 80,000 for waterproofing terrace and outer walls of the house..is this a fair rate? The rental itself is only Rs. 6,000 per month. It would take more than a year to cover these water proofing expense from rent alone.. 🥲guess.rental income is profitable only in cities. (Enquired with 2 more people ..they all charge a flat rate of Rs.40 per sq.ft which include grouting & using dr.fixit)