We are currently renovating a 1970 house with a terrace. The ceilings in the interior were originally insulated with thatch. We removed that. Now the ceilings are completely "bare," so to speak. Only the concrete blocks are visible. We want to cover the ceilings with sheetrock and consider insulating the cavity between the ceiling and the sheetrock. But we have been told that ceilings in interior spaces are no longer insulated. That annoys us. Heat does go up and then escapes through the ceiling and attic (which isn't insulated at all), doesn't it?
We also read that at least the last ceiling under the attic should be insulated. In short:
(a) Do interior ceilings need to be insulated? If so, what insulation material should be used?
b) Should the ceiling under an unheated and uninsulated attic be insulated? If yes, what kind of insulation should be used?
c) Should only the attic itself be insulated? If so, what kind of material?