Why is one of the top floors of the bathroom filled with gypsum board perlite?

Apply clear nail polish around the hole to prevent the hole from expanding. >>>More

It is estimated that it could be due to several reasons:

First, mixed into the geothermal slab bricks. >>>More

That's up to you how many you have

I feel like we can use it together. >>>More

Yes. This shows that your room is a little smaller, so use various methods to make up for it, and this is also a way to make up for it.

A piece should be left on the ceiling of the bathroom, which is to install lamps.