Astrology and Vaasthu are interrelated. Pancha tatwas (Agni, Vaayu, Aakash, Bhoomi, Neer) and Navagrahas plays important role in Birth Horoscope and in Vaasthu. The science which integrates Astrology and Vaasthu can be called as AstroVaasthu.
Our Great Poet and Philosopher Thiruvalluvar had mentioned about the value of time and place in the below short poem.
Thirukural Verse 484
One may aim to acquire the whole world and succeed,
If actions are aimed at the right time and place.
The Time represents Kaalapurusha (Horoscope) and Place (space) represents Vaasthupurusha (Vaasthumandala).
It is always better to have preventive care rather than curing. In other words, the person should check the Vaasthu effects and defects of the house before buying it.
In case if the person has bought Vaasthu defective House, it should be corrected through demolition and reconstruction. If it is not possible to demolish, certain remedial measures should be followed to minimise the negative effects.
The various remedial measures are based on Yantra, Mantra, Tantra, using pyramids and fengshui. Benefits of these remedies are highly dependant on the defects of the house. For small defects, remedial measures may work immediately after one week of installation.
When there are Vaasthu rules, why it should be compared with Horoscope?
Ans. With the fusion of Vaasthu and Astrology, we can create better place for living. Suitable directions or house entrance can be fixed using the birth horoscope. According to Vaasthu rules, North and East direction / entrance houses are more auspicious. South direction / entrance is given less importance. Does it mean, South is not suitable to anybody? No. I had seen several people using South facing houses are quite successful. Planet Mars rules south direction and it should be strongly placed in their horoscope for their success.