I've made a little Dynamo workflow that will write the ceiling height of every room to a selected parameter. Useful for when you want to check minimum required room height with actual room height. You can download the Dynamo file through the link at the bottom of this page. You will need Dynamo 1.0 and the custom package 'Clockwork'.
First you'll have to create a 3D view with only the floors and ceilings categories visible (and maybe roofs as well depending on the model):
After that you select that 3D view to be used by the 'RayBounce.ByOriginDirection' in de Dynamo graph. The RayBounce node will return the first element it encounters in the given direction. In this case it shoots up from the room location. With the given view it will always find a ceiling or floor, unless you've modeled rooms outside the building with no roof, ceiling or floor above it.
After that there's some filtering for only ceiling elements and if needed some extra filtering for unwanted types of ceiling:
And then finally the 'Height Offset From Level' parameter from the ceilings is retrieved and set to the selected room parameter.
And with that the parameter has been set: