Also known askundli vastujyotish vastuplanets and vastugrah vastu
When the lord whose colour you need is debilitated, trace the chain of sign lords to the planet that cancels the debility and use its colour instead, creating a neech bhang raj yoga yourself.
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.
This is a subject of astro vastu. Different items represent different planets; if a planet is very negative in your kundli and you keep the item that represents it, the negativity grows further. Which item suits which home, and with what, is covered in interior vastu.
No. If it did, the owners of five and seven star hotels, which commonly have toilets in the North-East, would suffer first, and every South-facing owner would be ruined. Vastu must be read together with the planets of the person, which are exalted and which debilitated, instead of blindly applying one rule to everyone.
No, in that case an E4 door is completely wrong.
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.
As in a kundli, where Jupiter blesses whatever it aspects with full drishti, a devta also aspects the devta opposite it; Surya, for example, balances Varun. If you cannot balance a devta directly, balance the devta whose full drishti falls on it, and its gaze will set it right.
Members of one family almost always have nearly the same planetary placements; there is a symmetry among their charts, and that is why they are born into the same family. In that case the Sun was badly placed in all four charts, so the East-facing house harmed the whole family.
Go by the houses, not the numbers written in them: the top house is the 1st house (East) and the 4th house is North. If the planets on the North side are strong, the North direction is very good for the person. A kundli can even reveal where a person's house is, where its door is, how many windows it has and where a nearby river, pond or temple lies, so a map of the house can be drawn without seeing it.
Primarily the grih swami's, the person whose money is going into the house, because the house affects the owner and his next three generations; do not go by the name the property is registered in, such as a daughter. The facing and main door are chosen from the grih swami's chart, for example North if his Mercury is exalted or his North-side planets are strong. Where a child sleeps or studies is decided from the child's own chart: if the child's Mercury is weak, seat him in the South instead of the North, following the 180-degree rule for a weak planet.
Decide room by room. In your own bedroom use the materials of your exalted planet and not of your debilitated one; your daughter's bedroom is designed from her kundli. The house facing and common areas such as the drawing room and kitchen are decided from the grih swami's kundli. Many people make the master bedroom in the South-West by default, which is wrong when Rahu is debilitated: such people suffered there and got very good results after moving to another direction.
The planets are still there even if the kundli is lost. A perfect kundli can be made from the thumb through Bhrigu Samhita, and Nadi astrologers also prepare it. A Prashna kundli can be cast, and Samudrik shastra (reading the body) also shows which planets are exalted or debilitated. Get this worked out by an astrologer.
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.