Dear unver, thank you for your suggestions. However, due to the zoning, I cannot show 1 more floor, namely the basement. --Enlarge the upper raft S002 slab 50 cm down, it will be intertwined with the P01-02-03-04 curtain reinforcements. I can't understand what you mean in this sentence. Should I lower the P01-02-03 curtains 50 cm and extend the S002 foundation over them?"unver":37cd55mr" said:Hi My Suggestions; --Based floor separate modeling is better, --Reduce live loads in the attic, remove wall loads, --1st floor stair support like other floors, [color= #FF4040]--P01-02-03-04 give the horizontal load from the upper (S002) foundation to the bulkheads,[/color] --Enlarge the upper raft S002 slab 50 cm down, P01-02-03 -04 curtain will be intertwined with the reinforcements. (I still do not recommend making a gradual foundation.) Take it easy Ünver ÖZCAN