वास्तु मण्डन (मण्डन सूत्रधार - गृह, राजप्रासाद, दुर्ग एवं नगर-वास्तु सटीक)

Ch. I – Miśrakādhyāyaḥ 43
143-144. At the inception of the foundation, Upamarmas should be
avoided in the middle of the plot. If that Vāstu is afflicted by
Marma, walls, pillars, nails or unclean things, it will be disastrous
for a house.
145. Measurement of the Marmas is done by twelve or sixteen units
but according to some it is measured by one, two or three fingers.
Thus ends Marmavāstu.
146. Though each of the Pādas are occupied by Gods, even then the
Puṁvāstu is to be dug first of all. It is beneficial if dug in the
cavity of the abdomen; if dug on the other parts of the body, it
brings destruction.
Such is the principle of digging in the Puruṣavāstu.
147. The house of a Brahmin will have nails made out of the Aśvattha
tree, it will be thirty-two Aṅgulas in measurement and quadrangu-
lar in shape. For a Kṣatriya it will be sixteen⁸ Aṅgulas, made out
of the Khadira tree and octagonal.
148. For a Vaiśya, it will be twenty four Aṅgulas in length made out of
the Śirīṣa tree and hexagonal. For a Śūdra, it will be twenty Aṅgulas
made out of the Arjuna tree, and it will be strong and circular in
shape.
149-150. The thread will be sturdy, eight Daṇḍas (32 hands =48 feet)
in length and one Aṅgula in breadth. For a Brahmin, the thread
will be made out of Darbha (a type of grass), for a King, out of
Muñja, for Vaiśya, out of Kāśa, for Śūdra, out of jute, silk, and
cotton; these will be made universally. In the laying out of a
house, the nails should be inserted from Vahni (South-East
corner).
8 It is twenty eight Aṅgulas in A.P.