I want to raise the living room a few centimeters higher than the living room, is that okay?

You can make a ceiling, 8 cm to 12 cm, as long as you make sure that the downlight or spotlight can be put on. If you do double layers, you can also make 6 cm for each layer and 12 cm for two layers. It looks much better to make the top thinner, but it is more troublesome for the painter to batch the wall and brush the paint in the later stage, and the operation is still okay. >>>More

This comes from a floor.

Some can be used a little wider. >>>More

It doesn't matter if the bedroom door is repaired with a threshold.

Generally, there is a reflective light trough of 15 cm! 10 cm without light trough. It depends on what kind of curtain you install and then choose whether to keep it. There is a reflector trough 15 centimeters! 10 cm without light trough.

You're referring to the standard of verticality after plastering the wall. >>>More