Does everything taught today also apply to an apartment or flat, or only to a kothi?
Everything taught today applies to flats as well, except bhoomi vibhajan. In a flat it is already done: the space left around the building during construction is its Pishach bhoomi. Ati marma, zoning and directions all apply inside the flat.
Related questions
Are marma and ati marma applicable in flat vastu?
Yes. The ati marma of a flat should also be found and kept free, just as in a house or plot.
At what degree do the corner directions (vidisha) fall?
North-East, South-East, South-West and North-West fall exactly 45 degrees from the main directions. Where they fall in your own flat becomes clear once you do the zoning.
Does zoning work differently for plots in hilly areas?
No. Zoning is done the same way everywhere; only the measured tilt differs, and it has to be taken for each site.
How do we find the degree of a plot when neither it nor anything around it is built?
Ask the engineer who draws the basic plan to show the surrounding roads, straighten the road in your map and take the road's degree. You can also use any parallel neighbouring building, since parallel buildings always read the same, ask the engineer which line the house will follow, or visit the spot.
How do we know that a tilted-looking map has been drawn to zero degrees North?
Open the location in Google Earth with North set at the top and compare. If the plan looks identical, it is drawn at zero degrees and is zoned without rotating the chakra; about 90 percent of such tilted maps are drawn that way. If in doubt, rotate the map until one straight side is straight and take the tilt from that side.
How is zoning done for a flat?
Exactly as for any plot; flats, industries and every other building follow the same method. Finding the centre of a flat can be hard, so use AutoCAD or the paper method for irregular shapes. Only a temple differs, because it uses the 64 pad grid, where North falls between N4 and N5.