Objects not sitting on other objects

[damienREEJK]

I have imported a basin and it is not sitting at 900mm high, even though it is set in the properties. I have noticed this with a lot of items. Can anyone tell me why this is happening? 

[jay_colcombe]

Many of the Items have a Default Elevation Parameter in them which drives this position.  You can find this in the Edit Type Properties within Revit but does not appear to associate to anything?

[nozci]

You can change z justification if available: