If a plot / construction / hall or room be say 45 x 27 feet - divide the same into 9 parts as shown. The middle portion is central area measuring 15 x 9 feet.

Divide the middle area further into 9 parts as shown.
      The marked area is prime central area.

If by construction of a balcony, the length of the plot / construction / hall / room increases such divisions as explain in figure 1 get modified as shown in figure 2.

For example if balcony is 6 feet, length of the total plot becomes 51 feet. Accordingly central area now be 17 x 9 feet (as opposed to 15 x 9 feet earlier) and prime central area would be 3 x 5.6 feet (as oppose to 5 x 3 feet earlier.)

If there be defect in the central area of a plot / construction / any room / floor (storey) / a room or any floor / terrace, its effects is marginal. If However such defect is in the prime central area the consequences are serious. If there be bore well, septic tank, underground water tank, sump, heavy machinery, over ground / over head water tank, pillar or column or the floor level is higher or lower in this prime central area - It has a debilitating effect on the head of the family / first child or the whole family. It may even lead to loss of progeny.
            If in a construction, if there be open space in the front and construction is pushed back, this central space of the plot, construction and the bedroom must be separately considered. In all these three central areas there should be no vastu defect.
           The central area should be marked as explain in figure 1. For locating the central areas for construction etc. follow the sequence as explain in figure 1 only. Care be taken that while identifying the central area of construction - only construction dimensions be considered.

Generally it is observed that the cental area of only ground floor is identified. However we may be constructing balconies on the top floor or terrace with the result that the size of the construction is now different and thus the central area of the building itself gets changed. In such a case if there be any construction such as bore well / septic tank / underground water tank or heavy installations in such modified central area or uneven floor level at this place the debilitating effects will visit the head of the family / first child / all even the whole family.
           It is for this reason that the central area of the construction of each storey / floor be taken from the roof / terrace only. if there be defect in the central area of any floor, residents of that floor only will suffer the effects. However the defects of ground floor and roof affects all residents.

In figure 1, two different plot / constructions are joined. Their central areas are also separate.

In figure 2, as shown in both the constructions if the middle wall is totally or partially removed, it notionally becomes one construction only and hence the central area of the combined plot / construction will only be one. If such modifications are under taken on one floor and no such corrections are applied on the upper or lower floors, it becomes a serious vastu defect causing untold miseries to the house leading to loss of progeny even.
Note : If however the middle wall is not totally disturbed and a door is constructed instead, this defect is overcome.