2. It mainly depends on your own design scheme. The height of the lamp trough depends on your design requirements for the light source and also depends on the cooperation with the beam opening. Sometimes it's not too much to hang 40CM high in order to cover up the ugly. Generally more than 6 cm (modern simplicity), but also has a wider internal angle. There is also a small overlap on the front. As long as the visual proportion is appropriate.
Extended data:
Tips for living room ceiling:
If the height is 2.8 meters to 3 meters, you can choose to make a ceiling and a high-end atmosphere.
If the floor height is less than 2.8 meters, it is not recommended to return to the ceiling, because it will appear that the room is short and it will feel depressed inside.
3. Ceiling made of different materials will have different feelings according to the height of the ceiling.
4. Living room, bedroom, corridor and other spaces will be suspended, mainly due to dust accumulation. Therefore, the cleaning of the ceiling in these spaces is mainly dust removal. Dust can be removed with a soft cloth or a feather duster. If you encounter serious stains, you can polish them with sandpaper and apply a layer of paint of the same color if necessary.
References:
Baidu Encyclopedia: House Decoration: Ceiling