There is close relation in Astrology and Vastu. The directions are ruled by planets, i.,g., East by The Sun, West by Saturn, Northeast by Jupiter etc.

Our Horoscope is a directional map of Zodiac at the birth time.
Ascendant ( Lagna) or 1st house shows East direction, 7th house west,
10th house north and 4th house south. Signification of 12 houses of
horoscope and directions in Vastu are close related. Moon signify and
have control over water, as well as other planets signify different
things and matter.
We consider each individual horoscope as a different case. If a person
ruling by Saturn, then East direction govern by the Sun will be not
beneficial for him. West direction govern by Saturn can only give him
better result, as well as Blue shades will give him more beneficial
results. If a person ruling by Venus, then Jupiter’s direction can
North-East, reduce his Venus planet’s beneficial energy. If we change
his direction accordingly Venus, he will enjoy more positive result of
Venus.
After a study and research, of, correlation between Vaastu and
Astrology, we found new concept of every direction have different
results on different person, accordingly there planets in horoscope.
So ASTRO – VASTU is more precious and result oriented. Only fixed rules
of Vastu can give you adverse results, while ASTRO- VASTU can improve
yourself.