Getting composite walls to clean up with composite roofs

[Paul King]

Has anyone come up with a way to get composite walls to clean up with composite roofs in section?

I have a composite roof used as a suspended ceiling, with a skin used to represent ceiling battens and a skin for plasterboard.

I have a composite wall used as the vertical face of a ceiling bulkhead, with a skin for plasterboard, and a skin for timber framing

The plasterboard material is the same for both composite elements, and the ceiling battens material priority is the same as the wall framing material priority.  Intersection priority for layers containing wall and ceiling elements are the same. 

Both elements are new, and their edges are perfectly aligned to meet at a corner in section

I have tried merging the two elements.

However nothing seems to result in a clean intersection, where the cut view shows plasterboard wrapping down the bulkhead wall and across the ceiling below.   

What am I likely doing wrong?

[Paul King]

That is an interesting idea! - I did not know composite walls could clean up through openings in composite roofs (as apposed to holes formed with roof edges)