I recently hosted an online user group where we focused on Revit modeling techniques to leverage the model in Navisworks. One of the topics we reviewed that is new in Revit 2012 is the Parts tool. In case your not already familiar with this tool, you can divide layered Revit structures such as walls, Floors and Roofs into component layer parts.

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Standard Revit wall joins create wall parts that overlap each other and do not intersect the horizontal roof volume symmetrically. The resulting wall part shown above is considered one part and cannot be divided further in this view.
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Navisworks users familiar with the Timeliner will immediately recognize the benefit of being able to animate the construction sequence of a wall type where the internal structural core is built first and the finish layers are completed later in the construction schedule.
Remember Physics class? For every action there is an equal and opposite reaction!
In this example we see an elevation view of the interior wall core layer displayed in an isolated elevation view. Prior to dividing the wall into component parts the roof was modeled and as it extended into the wall core Revit obligingly removed that overlapping boundary for us.
It is however possible to create conditions in the model that will support both of these functionalities. I often speak of the importance of the order of operations in Revit and this is one of those instances where it is necessary to change our modeling workflow to take advantage of the Autodesk tools instead of struggling to make them work the way we think they should. :-)

Before dividing the walls into their component parts we need to modify Revit's default wall joins.
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Use the Wall Joins tool to override the default wall joins replacing the overlapping condition with a mitered corner.

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We all know that this is not truly how the materials will meet at the wall corners, but for the sake of modeling and documentation there is little negative impact...and much to gain.
As a result the mitered wall joins will create wall parts that are also mitered. As you can see in the elevation below this allows the user to continue to divide the wall component parts to simulate concrete lifts, etc….
We must first understand the tool and its capabilities before we can explore how to apply it in a unique way!