Can a rectangular shape be used in the North?
It is better avoided. In the North, choose a half-moon type shape as far as possible.
Related questions
Can a circular POP ceiling be made in the North?
Yes, a circular shape can be made in the North.
Can the ceiling be painted brown?
Not at all. Brown on the ceiling starts representing fire in the space element.
Drainage is listed under the water element. Is a drain line in the water zone negative?
Underground water movement 1.5 to 2.5 feet below the surface is not treated as directional, just as groundwater flows in every direction under the land; it becomes a dosh only when water is drawn up. So the drainage pattern itself is not a dosh. But a drain inspection chamber built at a wrong place and left open causes trouble, and dirty water flowing anti-clockwise has a considerable negative effect.
Flats are small and a half-moon sofa set does not fit in the North. Can a rectangular arrangement be used?
Yes. A rectangular arrangement can go anywhere, because the earth element is present everywhere.
If a planet's colour (for example Mercury's) cannot be used in its zone, can the colours of its friends or of the zone element's friends be used?
First see what Mercury is in your chart (exalted, bhagyesh or lagnesh, which supports health) and where it sits. If its own colour cannot be used in that zone, use the colours of Mercury's friends, and the colours of the friends of that zone's element must also be taken.
A North window has its shutter kept closed. Can the shutter be removed and a jali (mesh) fitted?
Yes. The North results then start coming, though not fully; you get as much as is open. Through a window only air comes in, whereas people come in through the door.