Have you ever wondered why seemingly random associations happen within Revit between your geometry and reference planes depending on their proximity?
When Geometry is placed near to a reference plane there are some automatic associations that Revit creates. This can be either useful or very annoying depending on what your intended outcome is, 9/10 it is unwanted automation.

Here is the reason and how you can take back control of your Revit family and counter Revit’s lust for automation.

I’m going to use a simple example.

I create my reference planes that are going to control my family.

I add some 3D geometry without any constraints being added.

When I change the Length parameter the 3D extrusion moves with the ref plane even though I didn’t ask it to.

Why? – Automatic Sketch Dimensions!

If you enter back into the extrusions sketch, hit visibility graphics (“VV” or “” or “View>Visibility Graphics”) in the annotation categories tab, you will find that a little visibility option is unchecked called automatic sketch dimensions.

Here you will see the reason why the profile is retaining its shape and where the association with the ref plane is coming from.

Drag the dimension away from the ref plane and place it on the other side of your boundary lines to remove it (you can’t hit delete. Too easy). Now there are no dimensions to the ref plane from the sketch.

And there you have it, the geometry is no longer associated with the ref plane.

Hopefully this will go a long way to allowing you to take back control of how Revit is reacting when you are creating ref planes near geometry and why things are happening within your family.