Plan regions can cause some confusion related to their default behavior. This can become more complicated when involving floors in the view. I’ve included a few important items to keep in mind related to these topics:
Objects Intersecting a Plan Region
By default an object that intersects a plan region, but is not cut by the cut plane of the plan region, will be entirely visible.
Take a simple wall for example and a rectangular plan region. Say the wall is 3’-0” high and the Overall View Range of the View is set to Top 7’-6”, Cut Plane 5’-6”, Bottom 4’-0” and Depth 4’-0”:
The wall would not be visible in the view by default since it is 3’-0” high. So the plan region is added to include the wall:
In the example above the plan region’s Cut Plane is above the top of the wall, but includes the wall in the Bottom range. So it is shown in its entirety. If the Cut Plane was modified to be 2’-6” only the portion of the wall within the plan region boundary would be displayed:
Floors regardless of Plan Regions
Floors in Revit will display in the view as long as the floor is within 4’-0” of the View Range > Bottom. They do not have to be cut as long as this 4’-0” condition is met. For example if the floors top elevation is 0’-0”, 3’-11” will show the floor, 4’-0” will not show the floor.
This behavior is hard-coded into Revit and set up to allow the floor to be visible consistently through conditions with varying levels or split floor type scenarios.
Floors & Plan Regions
The 4’-0” threshold for floors will also be maintained with plan regions. Say for example you have 2 levels; Level 1 & Level 2 10’-0” apart. Level 1 has a floor, and level 2 does not. Level 2 has a plan region extending down negative into Level 1.
If the plan region Bottom View Range extends into Level 1’s 4’-0” floor display the entire floor object will be visible on Level 2. So the floor will be visible if the Bottom range passes -6’-0” [say -6'-1"] in this example:
If you keep the Bottom View Range outside this area the floor object will not be visible in the level above. So the floor will not be visible if the Bottom range stays above -6’-0” [say -5'-0"] in this example: