See, there are many different shastras (body of science or knowledge) and not just one. Different methods and approaches are written and prescribed in different scriptures.
So it is okay to consult Vastushastra before you construct a new home. But if there is some dosha (here meaning an anomaly in the land or the type of construction), simply chant Om Namaha Shivaya. Chanting this one mantra is enough to remove any negativity and any type of problems you may face.
You know, being in devotion removes all obstacles in one’s way. By being sincere in your Seva, Sadhana and Satsang, all problems get removed, and negativity disappears.
This is why mantras like Om Namaha Shivaya and the Mahamrityunjaya Mantra are so great. They have the power to remove all your problems and any negativity that may come your way.