Quick answer: For most houses in Gurgaon and the Delhi NCR area Fe 500D TMT (thermo-mechanically treated) bars made by a primary steel manufacturer and marked BIS (ISI) certified are best choice because they have high strength but also ductility a house needs to survive an earthquake. Fe 550D should be considered for taller or heavily loaded structures and corrosion resistant bars make sense in damp or waterlogged areas.

That’s the short version. The rest of this guide explains why so that you can ask the right questions before a single kilogram of steel arrives on your plot.