* You must [[repairing|repair]] any [[damage]] on the doors with a [[slate brick]] before [[improve|improving]] it.
* Activate a slate brick, right-click the door and select ''Repair'' or ''Improve''.
* The effective [[quality]] of the slate brick is affected by its damage and your [[masonry]] skill, it must be higher than the door's current quality.
* The effective [[quality]] of the slate brick is affected by its damage and your [[masonry]] skill, it must be higher than the door's current quality.