Bathroom ceiling plate ceiling from the ceiling is the smallest number
To cover the drainage pipe is appropriate, as high as possible from the ground. But if you have a ceiling of the exhaust fan or Yuba what to consider the location of those devices.
Preferably not less than 10cm
And no distance above it does not matter, the height of the bathroom you keep between 2.2 meters to 2.4 meters for the best size.
Too high winter yuba heating is not to force.
Too low a sense of space to suppress!