When several people live in a house, whose horoscope decides the facing and the main door, and how long does a house affect the family?
The griha swami's (house owner's) horoscope is used; the method is taught in the astro Vastu classes. The effect of a house carries on for up to three generations.
Related questions
Is choosing the door related to astrology?
Yes. With the person's astrology as the base, the door is chosen according to whom it will suit. The class covers three ways, by rashi, by exalted and debilitated planets in the birth chart, and by mulank, and the birth chart carries the most weight.
Can doors be opened anywhere by vastu, or must the birth chart be checked?
Check the birth chart. If the Sun in the chart is debilitated and you forcibly open an E3 or E4 door, it will be wrong and not appropriate at all.
If the Moon is debilitated, is a North-West entrance bad?
Yes, not just bad but very bad; the North-West entrance will have to be closed.
In my chart no planet is exalted or debilitated. How should I understand this for choosing a door?
There is nothing to read into it; not everyone has exalted or debilitated planets, and it is neither good nor bad. In such cases the door is chosen towards the direction in which the benefic planets sit, which was taken up in the evening astro-vastu class.
In the example of the Sun in the 8th house, would an East entrance have suited if the Sun had been retrograde?
Possibly, but then its degree and the aspects on it, such as a benefic planet's aspect, would have to be checked. A house is built only once, so such a risk should not be taken. Retrograde (vakri) planets are taught later in the course.
My Jupiter is exalted and my door is on N6-N7, towards the North-East, yet we have had no problems. Why?
The Ishaan (North-East) corner belongs to Jupiter, so people whose Jupiter is exalted can keep their door there. This shows how the birth chart decides which door suits a person.