I've never seen "cielo" for a house or a room ceiling, and I think a Mexican would make unkind jokes if someone used it like that.
The meaning I know for ceiling is "techo", which is normally the indoors side of it.
Mexicans use "azotea" for roof, when it's flat, but we commonly say "techo" for "tejado" when it's stooped and/or tiled.
El techo del comedor tiene una gotera.
The ceiling of the dining room has a water leak.
Colgamos un móvil del techo.
We hung a mobile from the ceiling.
Mi perro vive en la azotea.
My dog lives on the roof.
Se rompieron unas tejas y tuvimos que arreglar el techo.
Some tiles got broken and we had to fix the roof.