Garage work

[sholla]

Hello All,

Currently ground floor of my 30x40 house is vacant,
used for parking. I want to build a fully covered garage
with a 15x12 room and attached 6x5 toilet.

Initially I wanted to do this on a lumpsum materials
contract but there are no takers. People I contacted
either don't respond or say it is too small a piece of work.
Now I am thinking of first doing the civil work (mainly walls)
with a mestri (either labor or materials). Then find
a plumber and electrician.

For the civil works, total wall area is coming to be 875 sq.ft
excluding doors and windows. One mestri I contacted is
asking 2 lakhs (with materials, 6" blocks). He is super vague about
what is included. He keeps saying normal rates won't apply
and that he has to scrape all the columns for the wall joints.

I understand for a piece work there is a premium over the
usual rates. But how much ? I request the experienced members give me an
idea of what to negotiate for..