Ceiling Trim

Ceiling Trim is a special “ghost” build order used in Oxygen Not Included to force duplicants to clear or dig out a tile that is otherwise covered by natural terrain or debris. Placing a Ceiling Trim build order on a tile instructs duplicants to remove whatever occupies that space even though the trim itself cannot be constructed on a blocked tile; the build order remains queued and will cause duplicants to repeatedly dig the tile whenever new natural material (for example regolith from a meteor shower) falls into it.

Ceiling Trim does not become a placed object when issued on an invalid tile. Its primary function is as a persistent dig/clear command: duplicants treat the unfillable build order like a task to remove the obstruction, and they will continue to return to that tile to clear it each time it becomes covered. This makes Ceiling Trim useful for maintaining open space over vents, switches, skylight-dependent buildings, or any tile that must remain unblocked for machinery that checks sky exposure.

Practical notes and interactions:

• Use Ceiling Trim to keep single tiles free of intermittent natural coverage; it is especially effective against regolith that falls during Meteor Showers because the build order persists after the tile is cleared, causing duplicants to dig again if more material lands there.
• Because the trim never actually builds on a blocked tile, it does not consume materials or produce a constructed object; it only creates a task for duplicants.
• Ceiling Trim is commonly applied above utilities or sky-dependent devices (space scanners, telescopes, space-exposed sensors) to preserve their required sky view and maintain scan or sensor quality.
• Place Ceiling Trim on a tile and leave the order queued if you expect repeated natural obstruction; duplicants will automate the clearing without further player intervention.
• Ceiling Trim can be used strategically to ensure airflow-allowing tiles (like Mesh or Airflow Tiles) remain functionally unblocked for machines that care about sky exposure, since duplicants will remove blocking natural tiles even if those tiles would otherwise allow airflow.

Ceiling Trim is a convenience/workaround tool rather than a permanent building, intended to give players a simple way to keep crucial tiles clear of intermittent environmental debris.