Message A room has a negative ceiling heigh Architect Knowledge Base

Message: A room has a negative ceiling height.

The information in this article applies to:


When I work in one of my plan files, a message keeps stating,

«A room has a negative ceiling height. Any railings surrounding this room will not display in 3D.»

What does this mean and how can I fix it?


This warning will display when a room has a ceiling height that is lower than its floor height.

For example, if a room on Floor 1 has an absolute Floor height of 0″ and a Ceiling height of -12″, the warning will appear.

To resolve this issue, locate the room with the problematic ceiling height and raise its height so that it is located above the room’s floor.

To find the room and raise the ceiling height

  1. Open the plan in which you are encountering the warning message and select Window Fill Window Building Only from the menu.
  • Select Build Floor Rebuild Walls/Floors/Ceilings from the menu, or press the F12 key on your keyboard.
    • When the model rebuilds, the program will find the problem room and highlight it, and the warning message will display.
  • With the Warning message box open, locate the room that is highlighted.
  • If need be, you can move the message box by clicking and dragging its title bar.
  • When you have identified the problem room, click OK to close the message box.
  • If you do not see a room highlight when you Rebuild Walls/Floors/Ceilings, then the problem room is located on a different floor.
    • Go Up One Floor and/or Down One Floor and repeat step #2 until you locate the problem room.
  • Click the Select Objects button, then click in an empty space in the problem room to select it.
    • If you select an object other than the room, click the Select Next Object edit button or press the Tab key on your keyboard until the room becomes highlighted.
  • Message A room has a negative ceiling heigh Architect Knowledge Base
  • With the room selected, click the Open Object edit button. On the Structure panel of the Room Specification dialog:
    • Notice the Absolute Elevations. The absolute height of Ceiling (B) should always be equal to or greater than the absolute height of Floor (C) .
  • Increase the value of Ceiling (B) so that it is greater than Floor (C) .
  • Alternatively, you can decrease the value of Floor (C) so that it is lower than Ceiling (B) .
  • When you are finished, click OK to close the dialog and apply your change.
  • To confirm whether you have resolved the problem, Rebuild Walls/Floors/Ceilings once more.

    If more than one room in your plan is affected by this problem, it may be a good idea to reset all rooms to the default floor and ceiling heights.

    To reset default floor and ceiling heights

    1. Select Edit Reset to Defaults from the menu. In the Reset to Defaults dialog:
    • Click the radio button beside All Floors .
  • Check the boxes beside Floor Heights and Ceiling Heights .
  • Click OK to close the dialog and reset all rooms to these defaults.
  • Next, confirm that the defaults for each floor are correct. Select Edit Default Settings from the menu and in the Default Settings dialog, double-click on «Floor «.
  • On the Structure panel of the Floor Defaults dialog for the current floor:
  • You may also want to specify the desired Floor and Ceiling Structures. as well.
  • Leave a Reply