I've written a couple posts in the past (January 2012 and August 2009) about creating clearance elements for use with Revit's own interference checking. Toward the end of one post I mentioned incompatibility between using Detail Level settings with forms that are intended for interference detection.

I wrote, "Keep in mind that the obvious way to manage visibility by using Detail Level won't help us for now. Why? Detail Level doesn't work with Interference Checking, the solid has to be "visible". If we assign the clearance solid to use a specific Detail Level the Interference Check tool fails to see the solid at all even if we change the view to the correct detail level."

I continued, "The Bottom line, we can't use Detail Level to manage the visibility of clearance solids. We must use sub-categories or Yes/No parameters. Using sub-categories is a broader brush solution while Yes/No is more involved because you have to manage them at the family level. When we use these methods we can turn off the visibility of a clearance solid and the Interference Check tool will still find them."

All these years later the incompatibility remains.

We can re-use common forms for clearance families if we nest them into other families, they don't need to be "Shared" to work. We can use a different category element (for example Generic Model > Clearance) and it will detected as interference based on the host's category. Just don't use Detail Level settings to control the visibility of the nested clearance family either.

I also suggested that Autodesk standardize "Clearance" as it's own category. Alternatively they could establish a sub-category of Generic Model or even for all categories like they did with Hidden Lines (for Show Hidden). This way they could, at a system level, help us define what clearance elements are, how they are defined, what they should look like and how they should behave.

Somewhat related here's a May 2009 post I wrote about Design Options and Interference checking not working well together. It's still the same in 2014.

I wrote, "The Interference Check tool does not filter out results for elements assigned to various Design Options that "interfere" with one another. Keep this in mind the next time you are reviewing the results. You'll have a lot a "meaningless" collisions if you have any number of of options."

Stay interference free my friends!


Click here to view the entire blog post.