How do we count the length to width ratio of an L-shaped plot, for example 20 x 20 feet at the back and 10 x 30 feet in front?
An L-shaped plot is inauspicious in the first place. There is no special formula for its ratio; estimate it from its arms. The cut portion is a full loss, and how harmful it is depends on which corner is cut, which is best judged with the teacher case by case.
Related questions
Can we join all the corners of an irregular plot into a square and take its diagonals as the centre?
No. When part of the plot is cut, the true centre shifts, yet the square drawn through the corners stays the same, so its diagonals give a wrong centre. Diagonals were used in the earlier zoning class only because that map was regular, with the open parking area at the side.
If the plinth is a perfect right angle but balconies and projections stick out on the upper floors, is the shape irregular?
No, it is regular. Balconies are like the hair on a head; spreading hair does not change the shape of the body. The shape is the one in which the plinth beam and foundation were laid, because the underground current runs in that form.
Is a nahar mukhi (lion-faced) plot auspicious if it extends toward the South so that its South-East grows?
No. A South-East or South-West extension is not auspicious, because a plot needs its North-East extended. Even in an East-facing gaumukhi plot with a narrow front where the South-East is a right angle, the North-East gets cut, so it is not auspicious. A nahar mukhi plot gives results only when its North-East is extended.
Is there any length to width criterion for the centre, for example in a 250 x 50 feet plot?
There is no criterion for finding the centre; the centre is always the centre. The proportion matters for the plot itself: up to 1:1.5 is good (30 x 45 feet is ideal), up to 1:2 (30 x 60) is neither good nor bad, and longer than that is not good, with more loss the longer it gets. In such long plots many devtas fall outside or get cut, and they need treatment.
My plot measures 32 by 31, so one side is shorter. Is a corner cut?
If the shortfall is on the South-West side, the South-West is cut. Simply build on an exact 31 x 31 square.
On the first floor, a room or toilet is built out over the chhajja. Does it count in the shape?
Each floor is judged from its own base: a ground floor from its foundation, a first floor from the floor it stands on. Construction built out over chhajjas becomes part of that floor, and the centre of every floor changes with its own carpet area. If one family uses all the floors, the ground floor shape is the full shape, and a smaller upper floor, such as 25 x 25 over a 50 x 50 ground floor, does not make the plot cut.