Vastu conventions

The Vastu operations take a plot's measurements. They never ask for an address or birth details.

The text

Apart from Ayadi, classical rules come from one text: Varahamihira's Brihat Samhita, chapter 53, in N. Chidambaram Iyer's 1884 English translation, which is in the public domain. Each classical answer carries its verse in source, as verses. Numbers can differ in other editions.

Each answer has a basis:

• classical: the chapter says it, and source names the verse.
• convention: the chapter does not say it. It is present-day practice, or a choice of ours, and source is null.

Effects are the text's traditional statements, shortened. They are not predictions or building advice. Where the text's wording turns on caste or on women's character, we use plainer words; the verse is there for anyone who wants the original.

Measuring a plot

left and right are as seen from outside, looking at the front. A door's from_left_m runs from the left end of its wall, as seen from outside that wall.

The mandala sits on the plot's own sides, and each side takes the name of the nearest compass direction. Beyond 15° from a direction, the answer carries a plot_not_cardinal warning: the text assumes sides that face the four directions.

The two grids

81 squares. Verses 42 to 50 place all 45 gods. The door's pada follows the squares: a wall has nine, and the ninth is the corner, which is the first pada of the next side.

64 squares. Verses 55 and 56 give the classes of square and the two diagonals, but name no inner god square by square, so those squares return their class only. We read the perimeter from verse 71, which applies the door effects to either grid: eight stretches to a wall, with each corner shared by two gods. That reading is ours.

Three slips we read past

Verse 43 swaps two corners; verses 44 and 45 settle 81 as south-west and 73 as north-west. Verse 50 gives 33 for Prithvidhara where verse 47 gives 39. Some printings of verse 63 give 65 for Mukhya where verses 44 and 45 give 55. With these read that way, the six lines of verse 63 cross in the nine points verse 64 states, which the tests check.

Rules we do not apply

Verse 116 allows the east or north to stand slightly higher if it cannot be avoided, while verse 117 warns against either. We report verse 117's warning and do not relax it. Rules in this chapter sorted by caste are left out.

The rooms' score

The text places five rooms (verse 118) and protects the centre (verse 66). Only the ideal zone of those five is classical; the acceptable and avoid lists, and all the other room types, are convention. The score is ours, and data.scoring gives its weights. A room's position is turned into a zone by dividing the plot in thirds both ways, also ours.

Ayadi

The formulas come from a modern study, not from our own reading of the Sanskrit: D. N. Shukla, Vastu-shastra (1960), chapter 6, which reproduces them from Mallaya. source.via says so on each answer. Texts differ, so you choose with system:

Each result shows its base, multiplier, divisor and remainder, so it can be checked by hand.

• Cubits: measures are in hasta. For metres, send your own hasta_cm. Texts and regions differ on its length, so we do not pick one.
• Yoni: odd is good, even is bad and Dhvaja is best, as the source says. No remainder means the measures should change.
• Aya over vyaya: the source says these show gain and loss, but does not state this comparison. It is common practice, so it is labelled convention.
• No remainder elsewhere: we read it as the group's last member. The source says this only for the yoni.
• Rksha, vara, tithi and vayas: reported without a verdict, because the source gives none.
• nearby_passing: whole-cubit measures close to yours that pass. The search is ours; the formulas exist to choose among measures.

Griha pravesh

Griha pravesh dates are already in dated muhurat lists.