Auto Join All Add-in for Revit

From Moustafa Khalil's website...

Join All elements intersecting the selected element

This command will help you to only join all intersecting element to the element you will select. The best example scenario for this is to select a floor slab and it will join all walls, columns, beams, whatever intersecting it.

How it Works

1. Click the Join element push button
2. Select the Column.
3. the result will be like this.

Auto Join/unJoin All Elements in the project

This method will help you to join all the elements in the project, and if it failed to join any of these elements for any particular reasons, it will isolate the failed elements by the end of the command. this
help you locating the error, and to correct it, if you wish. Then you can cancel the isolation by [shortcut key (HR) ] to unhide all elements in the view…

UnJoin All

Same procedural of Auto Join All is applied on Un-Join All.

There's more information available on the Moustafa Khalil's website.