vasthu is also based upon the position of navagrahas as seen in hindu temples..d

Every direction has a corresponding planet. If the planet is weak in a person's birth chart and the corresponding direction is also weak in the person's house the effects and remedies are charted accordingly. 

Eg: North, Planet Mercury: Presence of toilet in North. Mercury malefic in birth chart Result: communication disorders, lack of concentration, restlessness, instability, eye illness, throat aches, anemia. 

Thanks

Sabina Vanjani

Vastu Analyst