Vastu 

Vaastu is a pure science and is just the distribution of the energy in the constructed place in such manner that we have proper utilization of the cosmic colours , which comes to us in form of energy by light (Natural / artificial).

It is believed if there is proper circulation of energy in a place, the work efficiency in that place would be smooth , relations would be healthy and the native would lead a healthy and prosperous life.

Arrangements as per Vaastu could be made on already constructed place with some adjustments , alteration and additions. Though there is no need of any civil changes necessarily to be made for rectification , though what ever blunder mistake might be there , there is always an alternate to it and solution , which is very convenient and economical too.