Vastu Shastra is inspired by Hinduism, especially Tantra. Nothing to do with Vedas.
The premise of the purusha mandala is the Ashta Dikpalas from Tantra, or guardians of the Eight corners of the earth. Its base construction is inspired by the belief that the sun moves around the earth, but from north to east to south to west.
In the veda's the guardians are the Adityas, sons of Aditi.
That is why the Brahma Muhurata or time between 3 to 6 AM is the starting point and is indicated by the north east. But the guardian diety of the north east is Shiva as Esanan. That is why our northeastern state is called Arunachal Pradesh.
Next time you want to learn something, try humility. Else you get to learn from "scholars" like sreekumar.
read below Sthapatyaveda
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Sthapatyaveda, also called Shilpa Veda, is the Upa
Veda (supplementary branch) of Atharva Veda.
Sthapatyaveda deals with planning, designing, and
construction of houses, villages, and cities. Vaastu
Shastra, the Indian science of Architecture, has its
origin in Sthapatyaveda.
Sthapatya means establishing, and Veda means
knowledge. Sthapatyaveda means establishing a
relationship between the dweller, dwelling and
cosmos. This relationship maintains a cosmic order
between the dweller, dwelling and cosmos. This is
the same knowledge that was used to design temples ,
houses and cities.
Ancient civilizations around the world were
influenced by this architecture, remnants of which
still exist.