If you've ever tried to override the line style of a web joist in plan, you may have ended up with some unexpected results if the member is sloped:
A Plan representation of elements is applicable when the element is parallel to the horizontal work plane of the view. Since the beam is sloped, it's using a 3D representation rather than Plan. To get a better understanding of what this means, open up the web joist family.
If you cross select everything in 3D, use the Filter tool to select only Lines (Web Joist), and then go to Temporary Hide/Isolate > Isolate Element, you'll be left with the following model lines:
If you select a line, go into its Properties < Visibility/Graphics Overrides and choose Edit, you'll see that line 1 is set to display in Plan/RCP views, while lines 2, 3, and 4 aren't. So when you have a flat beam all you see is that top line in coarse. In this dialog, you can also note that while the Plan/RCP category can be modified, all of the elements will display in 3D.
So when your joist is sloped, Revit is using the 3D representation, and you're seeing all of those lines in Plan. There are a couple of ways you could move forward from here - I'm going to go over using Subcategories as an option:
- From within the family, go to Manage > Object Styles.
- In the Modify Subcategories section, select New.
- Create a name for your new Subcategory - I'll use 'Web Joist - Coarse 3D' as an example - and keep it as a Subcategory of Structural Framing.
- Select OK to exit the dialog.
- Select lines 2, 3, and 4.
- In their Properties, scroll down to the Subcategory parameter and change it to the new one you just created.
- Load the family back into the project.
- In your plan view, open Visibilty/Graphics.
- Expand Structural Framing and clear the checkbox for your new subcategory.
- Click OK to exit the dialog: