Revit (and by extension Navisworks) wall areas and volumes are calculated based upon the centre of the wall. Because of this, there is no automatic way to get an 'actual' wall face area or volume. There is no way around this that I know of. For instance, I have tried material schedules, wall wraps and paint tool. The good news is if you know this, you can compensate for it. Also, the bigger your building the less you will be 'off' by percentage.
1. Does anyone have a reliable workaround that I have missed?
2. Is anyone using 'Parts' for this?
2. Why does Autodesk insist on leaving it this way? Is there a good reason it is the way it is?