Facing East, the left hand is North, the right hand South and the back West. The eyes, nose and ears, the doors of the body, are all in front, so doors and windows belong in the North-East, East and North. Lying down, the belly slopes away from the navel on all sides, so the plot should slope to the East and North; the navel is the body's exact Brahmasthan.
The left foot is slightly lighter and smaller than the right, as shoemakers know, so North is kept light and South heavy. The front of the body is soft while the back is strong, so the East side should stay light and open while the West and South are heavy.
Water drunk collects in the stomach towards the North-East, so the underground water tank goes in the NE. Food is digested by the jatharagni (digestive fire) towards the South-East, so the kitchen goes in the SE. Waste leaves the body from its West-North-West, so the toilet belongs in the WNW, and urine flows towards the NE, which is why the slope goes there.