Hello, we 'd like to level our 1800sq ft house on concrete slab. we do not want to spend too much on the foundation.
Please let me know. Any suggestion or advice would be appreciated.
The only person that can give you a reasonable cost is someone that has seen the house and can find out about the soil causing the settlement.
6" is more than normal settleing so you will need some real help in finding the cause and salution.http://en.wikipedia.org/wiki/Geotechnical_engineering
6" sounds a bit serious, did it happen over night?
The first problem is to figure what caused it, probably water. Fix it, Then worry about the floor.
Time to get a soil engineer out there. This is going to require some underpining or some other sort of stabilization.