Placing an Aligned Dimension across the corners of Air Terminals in Revit

Ever tried placing an Aligned Dimension across the opposite corners of an Air Terminal and it hasn’t worked. This blog will explain how it’s done.

Normally, using the Aligned Dimension tool will result in either a vertical or horizontal dimension because edges are selected, if we select the corners, an aligned dimension will result. To create an aligned dimension requires picking the dots displayed at the corner where two edges meet, to activate the dot requires the user to ‘Tab’ through the selection of edges and then each corner until the dots are displayed - except sometimes the dot refuses to appear, if this has happened to you, read on.


If the dots refuse to appear, it’s because of a setting within the family, not a problem with the dimension. The resolution is to edit the air terminal family. Follow the procedure listed below to edit the family.

  • Select the Air Terminal within the Project, pick the ‘Load Family’ option within the ribbon to activate the ‘Family Editor’.


  • Change the view to Floor Level –Ref Level.

  • Select at least 2 or more edges that define the perimeter (highlighted in yellow) of the air terminal.
  • Change the ‘Reference’ property from ‘Not a Reference’ to ‘Strong Reference’ – this will define that Aligned dimensions will snap to the corners.

  • Load the family back into the Project using the ‘Overwrite the existing version’ option.
  • To test the modification, use the Aligned Dimension tool, position your cursor over a corner of the air terminal, tab until the dot appears and select the dot, repeat this exercise for the opposite corner and place the aligned dimension in a convenient location.

Take a look at my other blog posts for more Autodesk Revit tips and tricks. If you have any enquiries, please send us a message:

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