False Ceilings with Lighting and Painting

Yes, false ceilings reduce heat exposure from the roof since the heat gets trapped between the soffit and false ceiling layers. But it won't reduce the heat exposed from the walls. If you don't have air conditioners, you might feel some discomfort in the nighttime due to the hot air trapped in false ceiling layers. But you can use the exhaust fans (in & out) above the false ceiling to replace the hot air with fresh air.

That depends on your actual requirements and purpose. If you are doing it to improve the aesthetics of your interior space, the gypsum board false ceiling is the best option for both design flexibility and longevity. Or if you need the false ceilings just for thermal purposes to reduce the heat, you should go with the 2x2 modular grid false ceiling with vinyl-faced gypsum tiles to save your budget.

False ceiling layers are usually measured in sq.ft by multiplying their length and width, while less than 1 ft width is taken in running feet and considered as sq.ft. For instance, if it's a plain false ceiling for a 10x10 room, the total area would be 100 sq.ft only. However a cove design false ceiling would be 164 sq.ft since it requires a second layer to create the cove provision for the LED string lights.

A grid false ceiling can last up to 5 years, while a gypsum plasterboard false ceiling can last over 10 years if properly maintained. However, the false ceiling's lifespan depends on many factors, such as the building's internal quality, weather conditions, maintenance, handling, etc. Seepage, moisture, adverse weather conditions, seashore wind, frequent weather changes, and poor building structures can severely affect the false ceiling's life.