The Wall That Won't Host a Door
A junior technician is placing doors in a two-story clinic model. On the ground floor, doors host and cut cleanly into the 200 mm exterior masonry walls. On Level 2, the same door family refuses to cut; Revit reports that the element cannot be placed on the selected host, and the wall highlights as a solid mass with no visible layer lines in plan. The Level 2 walls were created by selecting the Level 1 walls and using Copy to Clipboard / Paste Aligned to Selected Levels. The project uses a single wall type, and the technician insists nothing was changed. The deadline is end of day and the project lead wants doors placed without altering the architectural wall assembly.
1. Diagnose the most likely cause and describe how you would confirm it before making any change.
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The symptom - a wall that looks solid, shows no layer lines, and rejects a hosted door - points to the Level 2 elements not being architectural walls at all. A common cause is that the copied elements were pasted as in-place masses or generic model solids, or that the paste landed on a wall type whose function is not set to a hostable category. Because Copy/Paste Aligned preserves the source category, the more probable explanation is that the Level 1 "walls" the technician copied were themselves mass or model-in-place elements that merely resemble walls.
Confirm without editing:
- Select a Level 2 element and read the Type Selector and the Properties palette - check Category and Type, not just the name.
- Open Visibility/Graphics and confirm Walls are on; if the element disappears when Walls are unchecked, it is not a wall.
- Use Select by ID or the Element ID to inspect exactly what was copied.
- Compare a Level 1 and Level 2 element side by side in a section view to see whether layer lines appear.
Only after confirming the category should you decide whether to rebuild the Level 2 walls with the correct wall type rather than trying to force doors onto a non-host.
2. The lead wants doors placed today without changing the wall assembly. What are the trade-offs of the realistic options?
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There are three realistic routes, each with a cost:
- Rebuild the Level 2 walls as the correct wall type and place hosted doors normally. Cleanest and most future-proof; the doors schedule, tag, and cut correctly. Cost: redoing the Level 2 walls and re-hosting any existing openings, which risks losing hosted relationships if done carelessly.
- Use face-based or non-hosted doors placed against the solid. Fast, but the door will not cut the host automatically, so you must add an opening or void manually. This creates a maintenance liability: if the wall moves, the door and opening may not follow, and the door may not appear correctly in wall schedules or section.
- Convert the solid to a wall if it is a mass, then host normally. Best of both if the geometry is right, but mass-to-wall conversion can produce unexpected layer thicknesses.
Given a clinic with many doors, the hosted approach is worth the short delay. Place doors only after the host category is correct; a face-based workaround today becomes a coordination problem at every future revision.