Building the trench where the foundation will be set – this is called Vaanam Vettal or perimeter trenching. The trench should be dug only after consulting a vastu aacharya. The position of the trench should be based on the position of the vastu purusha. A vastu purusha is the representation of a heavenly being (shaped like a man) on the plot. Here the cosmic man symbolizes energy and power. It would be a good idea to get the householder’s horoscope read before the trenching. If the shovel hits the vastu purusha’s head, the results will be disastrous for the occupants. Perimeter trenching or vaanam vettal should be done near the vastu purusha’s groin. If the shovel hits the vastu purusha’s back, this will bring misfortune to the householder’s parents.
The vastu purusha’s sleeping posture is something that changes with each passing month. The vastu purusha’s groin will be in the southeast side during the (Malayalam) months of chingam (August 16th – September 15th ), kanni (September 16th – October 15th ) and thulam (October 16th – November 15th ), in the northwest side during kumbam (February 16th – March 15th ), meenam (March 16th – April 15th ), idavam (May 16th – June 15th), in the northeast during vrishchikam (November 16th – December 15th ), dhanu (December 16th – January 15th ), makaram (January 16th – February 15th ) and in the southwest side during idavam (May 16th-June 15th ), mithunam (June 16th -July 15th), karkidakam (July 16th – August 15th ).
Through these representations, it is believed that the vastu purusha’s sperm falls into the earth’s uterus and grows into a house. Now how does one determine where the vastu purusha’s body parts are on your plot? The vastu purusha sleeps with his head on the left side and his vision straight. And according to the concepts mentioned above, he will lie in this same position for three months. For the next three months, he will lie with his head resting in another direction. With this, we can easily determine the vastu purusha’s groin. Never start trenching while the vastu purusha is asleep. It should be started only when he eats. These months should be noted. The vastu purusha sleeps during the whole of kanni, dhanu, meena and midhunam. The rest of the months, he will be awake during particular times on particular times for 3¾ nazhikas (one nazhika equals 24 minutes). In ¾ nazhikas, he will finish his chores and go back to sleep. The trenching should be carried out only during his dining hours. Also make sure you place the architrave only where the vaastu purusha’s vision stops. Also the foundation stone should be placed at the vastu purusha’s pelvis region. If there are 89 steps, then the 39th, 40th are the penis and scrotum respectively. The place where the stone is placed is considered to be the uterus. After filling the hole with pulses, place a copper pot over it. In this copper plate/pot, there should be five types of soil, five types of metals and some medicinal plants. Place a brick over it. Follow these guidelines properly and consult a vastu aacharya before building your foundation.