1st I choose for this tile side insulation. But later decide not.

As the insulation is too thin for effectiveness. It blocks the airflow between tile and traps the inner roof hot air from going out.

So I decide to DIY insulate the ceiling. Which is what I feel more directly affects me from the room side.

The ceiling is the most heat generate for the room as the ceiling sq ft is as big as the room floor.

Use the foam spray for the insulation. Brought a few box to try on my working room. Brought from shopee.







The foam expands about an inch thick. But if you want thicker, just spray another layer. The thicker, the more heat insulated. Spray some water before and after the foam. It help to expand the foam more.



It is a fast process and dry about 4-5hr. The next day, you are able to feel the difference.

Here is the result of the temperature difference inside the room without an aircon.





I can increase the aircon temperature to 29°C and it already feels cool. And maintain at 29°C for the whole day even it really hot outside. 

The left panel is the actual room temperature near the battery. (below the cabinet)  And the aircon remote temperature setting. I never get the same reading before that.



That saves my bill a lot when work from home.